Your daily forecasts from Boards.ie weather forum (NO CHAT)

M.T. Cranium

Friday, 17 December, 2010 _ 0650h
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ALERT continued for widespread heavy snowfalls spreading gradually from west and north to cover also east and south later today, then further outbreaks more concentrated on east and south over the weekend. Some risk of disruption and blizzard conditions at times. Very icy roads and anticipated travel delays or cancellations. Severe cold also, especially central counties overnight hours.

Situation update -- The very cold northerly flow is backing to NW'ly through the day, but will be reinforced by a fast-moving trough late today and winds will return to a more northerly direction. This trough will become the focus for snowfall to spread east beyond the current mainly sea-effect driven bands in the west and north. Particularly heavy snow bands are likely this morning around Mayo and eastern Ulster towards Isle of Man. Tonight the trough will promote bursts of heavy snow in the southeast. Saturday, another low likely to form off the west or southwest coast and move around the south coast towards Cornwall. This would set off periods of snow across the south. Following that, a stronger low likely Saturday night, moving past the south overnight and towards south Wales or southwest England Sunday, crossing southern England. This could set off very heavy snow in Ireland with strong northeast winds. Some further snow Monday, then gradual clearing, staying cold.

FORECASTS ...

TODAY ... Continued windy and very cold with heavy snow showers in parts of Connacht, Ulster, West Munster, inland north Leinster, and flurries elsewhere during the morning to early afternoon, amounts 8-15 cms heavier once again from about Mayo to Antrim. Accumulating snow in east and southeast only likely afternoon and evening, 2-4 cms by then.

Further east and south, morning will bring some sunny intervals with passing flurries or hail showers. Winds in general NW 25-50 mph becoming WNW 25-45 mph, backing in south only to WSW 20-30 mph late afternoon, mixed showers likely in Kerry and Cork at this point, with outbreaks of heavy snow further north across Clare and Galway spreading across the country during the afternoon and evening. Widespread icy road conditions.

Highest temperatures -3 to +1 C, except 2-4 in Kerry and Cork.

FRIDAY NIGHT ... Snow becoming rather heavy at times and spreading into the eastern counties while becoming more intermittent in the west, amounts of about 5-10 cms likely with heavier amounts this time in eastern counties and also across much of Ulster. Winds turning more northerly after midnight, with lows of about -3 C east to -7 C central and -4 C west. Widespread icy road conditions.

SATURDAY ... Periods of snow may become intermittent, with 5-8 cms further, very cold with light to moderate northeast to northwest winds, some sunny intervals could develop in the north and west, but highs only -3 to near zero C.

SATURDAY NIGHT & SUNDAY ... Renewed periods of snow becoming heavy across most of the country, with winds NE 25-45 mph in northern and central counties, somewhat variable and lighter across the south (although strong winds could strike there at times). Snow could mix with sleet near east or south coasts, but this may be quite limited. Snow amounts likely to be 10-20 cms but could reach 30 cms in some inland southeast counties and blizzard conditions are possible. Morning lows of about -4 to -7 C with daytime highs -3 to -1 C for most.

MONDAY ... There could be an extension of the snowfall period although becoming lighter, well into Monday with a gradual tapering off to drizzly light snow grains or freezing drizzle. Then it seems likely to clear late Monday with bitterly cold temperatures over the fresh snow. Temperatures on Monday similar to Sunday, -5 to -1 C.

TUESDAY ... With any clearing, Tuesday morning lows could be downright frigid inland, -12 C or even lower in parts of the inland southeast and Midlands, Ulster. Elsewhere, closer to -7 C ... afternoon highs in the range of about -5 to zero C, with some sunshine and some lingering ice fog or low cloud.

OUTLOOK ... Possible sleet or freezing rain that was entering the mix for the period Wednesday 22nd to Friday Christmas Eve, is now once again looking more like the chance of further snow, and there is now only a very slight chance for any significant thaw with some rain in the far south. This will all depend on the track of an Atlantic storm that seems likely to try to push the cold air back north to some extent, but is now being challenged by a wave swirling southeast from Iceland trying to phase in with that low. The most likely solution would involve light snow and freezing drizzle around Thursday night and continued cold into Christmas. Another storm looms for late Christmas into the 26th. At this point, we have to guess this one too may start to acquire a colder profile as we get closer to the time. But as of today, some models show this as a thaw with rain. We'll see how that works out.

Now, here's the updated snowfall chart, snowfall in cms.
Tonight refers to the period now to 0800h Friday, which may be one reason why Friday (0800-2400h) amounts appear reduced.

REGION ............ FRI ..... SAT ..... SUN ..... MON ..... TUES
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Ulster .................08 ...... 10 ..... 10 ...... 03 ..... 01

Connacht ........... 08 ...... 07 ..... 08 ...... 02 ..... 01

West Munster, Clare. 05 ..... 05 ..... 12 ...... 07 ..... 01

East Munster ......... 05 ...... 10 ..... 12 ...... 08 ..... 01

inland southeast ..... 06 ...... 10 ..... 25 ...... 10 ..... 02

Dublin/Wicklow/Meath. 04 ...... 10 ..... 20 ...... 10 ..... 02

rest of Leinster ......... 04 ...... 12 ..... 18 ...... 07 ..... 01

The weekend snowfalls may become blizzard-like in some cases, whether they are technically a blizzard or not may depend on wind speeds. But coastal parts of the east and south could see some mixing so that while it may snow the same amount, not all of the snow will cover the ground to same depths near the coast especially southeast Wexford and outer parts of Cork coast.

The situation is quite fluid and range of possible outcomes is something like half the above to 50% more than above. Local snowfalls Sunday could reach 40-50 cms on higher parts of Wicklow and Dublin mountains.

Updates as required.

ninebeanrows

I am sorry MT but i hope you are right.

No model is showing this however, infact no model is showing anything near this.

Weathercheck

Weathercheck wrote: »

I am sorry MT but i hope you are right.

No model is showing this however, infact no model is showing anything near this.

http://www.boards.ie/vbulletin/showpost.php?p=69605014&postcount=196

M.T. Cranium

Update -- Friday 17 December 2010 -- 1920h
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Forecast has been revised somewhat to reflect a longer and possibly less intense period of unsettled, at times snowy, conditions across the south from later tonight on to about Tuesday night or Wednesday morning now. There is still potential for any of these snowy intervals to turn heavy as the guidance is having much difficulty resolving waves that are likely to develop to the southwest and move past the south on almost a routine daily schedule for several days starting with Sunday. From tonight through tomorrow, the main snowfall potential comes from the remnants of what has been a powerful snow-maker over Ulster, but they have sea-effect added to the overall potential of this weak low that is a surface reflection of the polar vortex now moving southwest towards Ireland from Scotland. Although weak in terms of wind and pressure field, we have to be mindful that any disturbance interacting with relatively warm seas in this super-cold air mass has considerable snowfall potential, as the northwest illustrates today. Without further verbiage, then, here's an updated forecast and snowfall table (I think Pangea has one in his garden).

TONIGHT and SATURDAY ... Cloudy with outbreaks of snow, heavy at times in north and west, becoming moderate and possibly heavy for a brief time also in the east and south. The snow may mix with rain briefly near the south coast this evening. Further amounts of 10-20 cms in the north and northwest, 5-10 cms west and southwest, 3-7 cms east and southeast. Overnight lows about -2 to -5 C on average, some ice fog forming around central to inland northern counties anywhere that clears. Winds generally rather light except NW 20-40 mph west coast.

During the day Saturday, most of this snow will break up gradually but there could be continued heavy sea effect streamers in parts of Ulster and inland Connacht that may make some inroads further south. There will be a slight risk of localized streamers in the Irish Sea as winds become light northeast possibly later southeast at 10-15 mph. Sunshine may develop well inland and it will be quite cold at about -2 C to +1 C south coast.

By SATURDAY NIGHT, outbreaks of light snow possible across the south in a light to moderate ESE wind flow. This may combine with some streamer activity in the Irish Sea but large parts of central and northern Ireland will be partly cloudy to clear except for some lingering remnant coastal snow showers. Very cold in this clear zone with lows falling to about -10 C in some areas. Lows of about -2 C in the south with the cloud and snow.

SUNDAY, the snow will extend into the inland southeast and may at times reach Dublin and Wicklow, with winds continuing mainly easterly and highs of about -2 C. Snowfall potential with this disturbance about 5-12 cms with the larger amounts likely to be around Carlow and Kilkenny. The north may be dry with some sunshine breaking through higher cloud, but there would be a slight risk of snow showers there too.

MONDAY-TUESDAY, further outbreaks of snow in the south, always with the risk of some sleet or freezing rain nearer to the coast. Amounts of 5-10 cms each day in some areas. Highs of only -2 to 0 C and further north, where skies less cloudy, overnight lows for these days near -10 C inland and possibly as low as -15 C in a few places. Ice fog likely with rather slack east winds or calm.

WEDNESDAY-THURSDAY should be a somewhat less unsettled period with very cold nights, chilly days, and a few flurries in the mix, but there is some chance that even Wednesday could see some snow in the southeast from the last slowly departing wave.

OUTLOOK FOR CHRISTMAS EVE, CHRISTMAS DAY and ST STEPHEN'S DAY is highly uncertain given the spread on the models, but I would place my bet on a continued cold pattern with the risk of snow at times, however there is some chance of milder conditions developing with rain (this would be more like a one in three chance the way things are unfolding).

Here's the updated snowfall table ... I've reduced some of the heavier amounts but should point out that they could come back into play if we get stronger indications of a deeper low pressure system on Sunday, something that now seems a bit less likely but is not off the table altogether.

Predicted regional average snowfalls, cms

REGION ............ TNT ..... SAT ..... SUN ..... MON ..... TUES/WED
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Ulster .....................10 ...... 03 ..... 03 ....... 01 ...... 01

Connacht .............. 08 ...... 03 ...... 04 ....... 01 ...... 01

West Munster, Clare... 03 ..... 04 ..... 10 ....... 07 ...... 04

East Munster ........... 03 ...... 04 ..... 10 ....... 05 ...... 03

inland southeast ...... 03 ...... 02 ..... 15 ....... 10 ...... 07

Dublin/Wicklow/Meath. 05 ...... 02 ..... 10 ...... 05 ..... 02

rest of Leinster .......... 05 ...... 01 ..... 08 ...... 04 ..... 02

Remember, accumulated snow will be less than the totals, because this is low-density snow that compacts easily and further snowfalls settle on and then push down the original base even if there's no melting. Some melting would occur near south coast that might make some of this snow come and go during the day so there would be less on the ground at any point than the rate of snowfall suggests. On the other hand, some areas in the north and northwest have already gotten more than our predicted amounts for yesterday and today, so these estimates can work both ways. Hope they work out for you. Travel with extreme caution if you're heading into snowfall zones.

Pangea

Pangea wrote: »

Yeah Donegal defintely didnt bear the brunt of it as forecasted, must of shifted east or something , I dont understand it.

M.T. Cranium wrote: »

Update -- Friday 17 December 2010 -- 1920h
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(I think Pangea has one in his garden).

Just to clarify
In the above quote I wasnt talking about MT ,I was talking about Met eireann , because Evelyn Cusack said on wednesday night that there would be heavy snow in Donegal for thurday/friday with drifting , and then yesturday MT said that Mayo to Antrim would get the heaviest falls for last night and up to today and that turned out to be dead accurate.
Also at the time of my post there wasnt much snow in Donegal, but by this evening its heavy in many parts. But overall I think Mayo and Northern Ireland has more snow so MT was right. Keep up the excellent work.

derekon

Weathercheck wrote: »

I am sorry MT but i hope you are right.

No model is showing this however, infact no model is showing anything near this.

In fairness to you WC, you were right on with your forecast from this morning.

All due respect to MT, however Dublin & Leinster had a very disappointing night with just a "sugar coating" of snow. I also see the near 50cms of snow forecast for Dublin has been severely downgraded.

A truly disappointing night in Dublin for any snow lovers. Something that promised so much did not deliver. Simple as. :mad:

M.T. Cranium

Saturday, 18 December, 2010
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ALERT for heavy snow in eastern Ulster spreading southwest to north Leinster this morning. Local amounts of 5-15 cms possible. This may either miss Dublin to the north or skim past giving trace to 3 cms in Dublin. Another area of possible heavy snow would be west Munster, and isolated falls in Connacht. These are more showery hit or miss situations with 3-5 cms possible. Also, ALERT for widespread icy roads and some very difficult travel in Connacht and Ulster, consult the forum road threads and other resources for updates on travel.

Situation update: The heavy snowfalls in the north, northwest and parts of the southwest are becoming more localized as the strong sea-effect is being replaced by meso-scale troughs. The south central, southeast and eastern counties that escaped most of the snow may remain dry today in most cases, but could see outbreaks starting late tonight or Sunday, as low pressure currently moving past the west coast circles around to the south. Models are giving widely different tracks and intensity, so my forecasts will have to be on a consensus, but I think that there is potential for some heavy outbreaks later today around Cork and Kerry, and then spreading slowly further east across the south into the southeast on Sunday, with reinforcements on Monday and possibly yet again on Tuesday. The snow mentioned in the alert for eastern Ulster is likely to break up later today rather than moving across north-central Ireland but it is heading for counties such as Longford and Westmeath before totally disappearing.

In the longer term, most of the guidance points to a dry trend for the central and northern counties spreading more to the south after this series of waves moves past, then for another frontal system to try to move milder air into Ireland on Christmas Day. Chances appear about one in three for success on that venture, and more than one in three for a snowy episode as a result, while another outcome (less than one in three) would be for the cold to remain dry and hold the front back entirely. We're entering a pattern now where any half-formed low near south coast of Ireland could gain energy and turn into a sizeable snowfall event or even a snowstorm. And this applies to a considerable time well into the future as North America's storm track looks to be ejecting lows every 3-4 days into the latitudes south of Ireland, all of these heading generally towards France. Either one would eventually swerve a bit north bringing milder air and rain, or one could explode into a powerful storm that would be a blizzard-like snowstorm. In this pattern, it is really difficult to say which of several storms might do one of those two things, but it seems likely that in general, it will stay cold with this frontal boundary often just to the south. Sorry about the uncertainty, but such is the nature of this atmospheric "science." Even on the 48-hour time scale, systems are appearing and disappearing from models, such as the projected major storm for southern England on Sunday -- now more or less downgraded to a weak event. I'm keeping my eye on Monday when there's an energy peak that could work with the low then located south of Cork.

FORECASTS:
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TODAY ... For most regions, partly sunny and very cold, some drifting ice fog in valleys, icy roads, and light east winds (light southerly in west Munster). Highs for these regions about -2 C. However, some areas of snow are likely too. One will extend from parts of Down and Louth towards Meath, Westmeath, Cavan, Monaghan and Longford, but could also brush Dublin and Kildare. Heavier amounts are likely in Ulster this morning (5-10 cms) with lighter amounts as this cluster breaks up moving southwest at mid-day. There may be a chance of streamers for Dublin and Wicklow later today too, with local 3-7 cms amounts possible. Another area of localized snow could develop from Cork (city) west to Kerry, with 3-7 cms locally in this as well as some sleety showers close to the coast. There will also be scattered remnant sea-effect snow showers drifting around in parts of Connacht and West Ulster. Amounts there would be confined to small areas, 2-4 cms.

TONIGHT ... Clear and very cold in some central and northern counties, with just isolated flurries mostly near the coasts. Lows -7 to -12 C. Some ice fog developing. Cloudy in the south and southwest, parts of the west near the coast, with outbreaks of snow likely, 3-7 cms for some areas, affecting west Munster and possibly spreading to East Munster. Also a slight risk of snow showers near the east coast localized but heavy in a few spots. Lows in these regions about -4 C.

SUNDAY ... Outbreaks of snow likely across the south, possibly heavy in parts of Munster, later spreading to inland southeast, 5-10 cms with higher potentials. This may be somewhat patchy and intermittent with fog and coastal drizzle added, as winds come in from the SE at 15-25 mph. Further north, cloudy with some sunny breaks more frequent in the north, cold, highs generally -1 to +2 C south, to -3/-1 C further north. Light winds in many areas of the north, but some risk of coastal flurries.

MONDAY ... Once again, snow possible across the south and southeast, heavier in the inland southeast, 5-10 cms possible, winds E 15-25 mph. The temperature regime on Monday will probably repeat Sunday's for most regions, and it should remain dry in the northern two thirds except for some widely separated flurries in the northwest. Highs generally -3 to +1 C.

TUESDAY ... A few further flurries in the southeast, chance of sleety showers near the west coast, staying rather cold in the daytime, but bitterly cold for some during the early morning. Highs generally -2 to +1 C.

WED-THURS ... Dry and cold, some sunshine each day, lows could reach -15 C over snow and -7 C in most areas, highs near -1 C. Some snow possible by late Thursday.

FRIDAY (Christmas Eve) into SATURDAY (Christmas Day) currently looking unsettled and possibly a bit milder, but there is a risk of snow or freezing drizzle. For now, would say chances about 2/3 that it would stay cold and be a white Christmas from the earlier snow if not from falling snow.

OUTLOOK ... see situation report above.

The weather here today (Friday 17th) was sunny and the high was about 7 deg C. Expecting rain tomorrow.

As snowfall amounts are posted in the forecasts above, I will leave out the table for now, partly because it would require even more divisions to handle all the expected variations, but in general, it looks like the area around Athlone may stay closest to dry through the period, and areas from Cork to Waterford to Carlow might see the most snow during the period, once today's Ulster snowfall dies out.

Updates may follow ... but I can safely say that I may be asleep from 0800 to 1500 so in that time frame, would consult the forum discussion for updated forecast thoughts.

M.T. Cranium

Not really an update ... just comments on situation.

I got one forecast spot on, slept from 0800 to 1500.

Have been looking at all available guidance since about then and really every model seems content with its earlier development, whether right or wrong, and there is a growing tendency to develop low pressure over France around Tuesday and move that northeast to the North Sea by about late Wednesday. This would have the effect of slowly backing winds over Ireland from Sunday's generally ESE direction to mid-week NE or even NNE, although not a very strong gradient in most cases, and with the effects of a weak ridge of higher pressure running through northwest Ireland from its ultimate source in the far north.

From tonight through Sunday, the main player in the weather forecast for Ireland will be the slowly-advancing low off the west coast which is dropping almost due south before turning east. This is spreading 3-5 cms type snowfalls into some west coast regions and could continue to affect parts of west Galway, coastal Clare, then later Kerry and west Cork.

I continue to think there's potential for some fairly significant snow to break out overnight and into Sunday across the southwest and inland south to southeast. But there's no cause for an updated forecast at this point. As to streamers for the east coast, this remains a slight chance at all times now to late Sunday and perhaps a better chance on Monday with the more northeasterly fetch.

My status now is -- out for the day -- so would doubt there would be an update from me before normal forecast time but check around 0100 as I will be able to have a quick look just before then. Weather here is gloomy with rain or perhaps sleet moving in, it's cold enough to snow just above my elevation and I expect it will snow on the local foothills and definitely in the nearby mountains, although down around Seattle WA it could be as mild as 10 or 12 C, so there's quite a gradient here, we are currently at 3.5 C.

M.T. Cranium

Sunday, 19 December, 2010
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We can be fairly certain that it will remain cold until Christmas Day, but the prospects for further snowfalls remain quite uncertain. Most model guidance continues to indicate weak systems that do not spread much if any moisture inland, away from the southwest. However, two things could go wrong with that dry scenario, first there could be stronger development as hinted at on one or two of the models; and second, there could be outbreaks of snow where dry weather is indicated as the air inland is intensely cold while the air along the south coast is holding a temperature near 2 or 3 C. Also there is the issue of streamers moving inland from the Irish Sea at various times, which seems likely to happen somewhere on a daily basis. Not an easy forecast scenario for snowfall, and then there is the looming question of a possible breakdown to milder weather, which several models insist will happen on the 25th, while others hold firm to the colder regime. I'll keep my opinion a surprise to the end of the forecast.

TODAY ... Widespread ice fog inland, low cloud or mist gradually breaking up to give some periods of wintry sunshine, icy roads very likely ... some snow breaking out across parts of Galway, Clare, Kerry (inland) and Cork (inland), with rain or sleet along the outer southwest coast. By afternoon and evening, some of this snow could spread to other parts of the south and southeast. Watch for updates, this is not yet a "sure thing." But snowfall amounts where the snow does break out, could exceed 5 cms in places. Also there will be further chances for streamers on the east coast, affecting parts of Leinster and Ulster. Highs today should average -2 C with colder readings in north central counties, milder along the south coast (to 5 C on outer coast). For Cork city, a tricky forecast, mixed precip may move in and be divided by elevation as temperatures hover in the 1-2 C range. But there is potential for heavy snow in places around county Cork later on, as there will be during the whole day in Kerry (inland). Winds today generally rather light easterly but SE backing to E 15-25 mph south coast.

TONIGHT ... Some clearing, bitterly cold except for the southern counties where rather cold, lows generally -8 to -15 C (not quite this severe in some coastal areas around the east, north and west) while -2 to -4 C south, where a continued risk of snow will exist (updates may change this to amounts forecast). Streamers from the Irish Sea could give local 2-5 cm accumulations.

MONDAY ... Following another bitterly cold night with local ice fog and lows in the -15 to -8 C range (and again, milder in the south, near -4 C), the day will be cloudy with some sunny breaks, and possible outbreaks of snow in the east and south. There will be moderate E to NE winds at times, and the daytime highs will be in the range of -4 to +1 C.

TUESDAY ... Bitterly cold with ice fog to start, lows -16 to -8 C inland, closer to -4 C in the south, with risk of snow breaking out at times during the day, highs only around -3 C.

WEDNESDAY and THURSDAY ... Continuing very cold, some clear spots in central and northwest counties, where lows could reach -15 C each night, ice fog in places, while the east will see stronger NE winds and a risk of heavy snow in streamers or organized bands, highs each day around -2 C.

FRIDAY (Christmas Eve) ... Cloudy, cold, possible snow at times, but also some sunshine in the north. Temperatures remaining very low and similar to the previous days, but perhaps a bit milder in the south and southwest.

SATURDAY (Christmas Day) ... At this time, the odds seem to favour a cold day with snow but sleet or rain are possible in the southwest. The cold spell could break down at some point, but model performance on this question has been erratic to say the least, so the conclusion is, only a gradual warming trend seems likely and it could be reversed at any point.

Watch for updates today and visit the discussion forums for all the latest thinking, especially between 0900 and 1600 when I am likely to be off duty (although it's always a good idea).

The weather here on Saturday (18th) was wet and chilly with a mixture of rain and wet snow, no accumulation at my elevation but probably sticking just a bit higher up. The temperature was steady around 2-3 C. It remains quite cold across most of North America although not too extreme in most places. A snowfall of several inches is likely across the lower Great Lakes on Monday and Tuesday.

Sonovagun

Where's the snow storm you predicted?

Ahorseofaman

Sonovagun wrote: »

Where's the snow storm you predicted?

all forecasts are done using current available information,a wealth of knowledge and (I think)a gut instinct based on years of experience.Current information can change within the hour but if you took the trouble to look back through MT's forecast you will find that he is uncannily accurate most of the the time.However he is not nor has he ever claimed to be God.Although even God got it wrong sometimes,look at the platypus.

up for anything

Sonovagun wrote: »

Where's the snow storm you predicted?

How rude! :mad:

smashey

Sonovagun wrote: »

Where's the snow storm you predicted?

MT gives probably the best advice and forecasts here and is always up-front with everything. To post a comment like that is at best disrespectful to MT and indeed all the other top-notch weather enthusiasts here.

M.T. Cranium

No worries, the errors are probably a mixture of over-estimation in some cases, and model error today (had the models been right for today when those forecasts were issued, I'm sure it would have been snowing across the southeast, the low that was shown going into south Wales ended up in northwest France. People in northern France are getting buried in snow today, just check "meteociel.fr" and look at the observations that come up on the map. Everyone north of Paris is talking about 20-25 cms of snow.

I appreciate the positive comments too. But I'm not too worried about taking some flak as long as it doesn't happen very often, the goal is of course to have it happen never, but as someone comments in another thread (I think), I don't claim 100% accuracy or superhuman powers (outside of my social life, of course). I would mention the long-range forecast as being reasonably accurate so far, in fact with any luck it may continue to do really well, and that's what I'm really working at, the short-range application is mostly to keep focus on the research (in other words, to give me a reason to keep watching very carefully, otherwise in this sort of research you tend to focus mostly on very large-scale features and miss a lot of detail.)

By the way, forecast update ... 06z GFS sides with my concern about no substantial warming trend, in fact, it looks quite cold all the way through to the end of its run on 4 Jan now with a ridge holding the mild air back at Christmas, and one time after that, before building up strongly again as the Atlantic goes totally back to sleep after this little stumbling around episode at Christmas. Unreal looking patterns this winter that only our ancestors saw (except they didn't, not being on the internet).

fizzycyst

MT, just wanted to say thanks again for giving your time to forecasting and updating for us EVERYDAY!. Much appreciated

smashey

MUSEIST wrote: »

I agree that M.T is excellent and nearly always right but the original poster has every right to ask what happened to the widespread disruptive snow. I know the models are to blame but when several people (not just MT) predict big snowfall and absolutely nothing happens people have a rigt to be peeved. There is a reason they are conservative at met eireann.

Everybody has indeed a right to ask but a bit of thought should go into how the question is put. As for widespread disruptive snow, take a look at Northern Ireland, Donegal, Ulster as a whole, Connaught, parts of the midlands and the south west. There has been disruption on a massive scale with heavy snow even if Dublin was by and large unaffected up to now.

I take a look in here when I get the chance and when I see something that looks to me like it could have been put a wee bit better, I will make a comment on it.

M.T. Cranium

Thanks folks, I must admit that my day has been largely non-weather-dominated to this point and I have no new thoughts about the short term yet, just getting back into it now.

This experiment of mine, essentially "what would happen if one person just took two years and followed the weather non-stop?" has had its risks and rewards. The risks are, burnout, tunnel vision, possible health complications, integration into normal routines which believe it or not still go on and involve all sorts of hi-jinks such as rounds of golf, poker sessions (live as well as some internet) and round the world yacht cruise (made that up). I also maintain threads on political forums and make a nuisance of myself all over cyberspace.

Rewards are, making a lot of friends, achieving a fairly high personal standard of forecasting (that much I can tell, comparisons to other sources difficult for me to assess because I don't hear as much as you might). Many rewards in the research department, when I say two years, I really mean five years at a less brutal pace for a much smaller forum in the UK and fairly frequent visits to Net-weather but with no forecasting routine there. Also, I have been about that active on an American forum where I am surrounded by meteorologists as well as enthusiasts. It's a rich gene pool there, maybe too rich at times.

Only a complete madman would even contemplate doing this, which is how I came up with my username. But now that I've been doing it, I find that I can handle it. The question of rest and shared load come to mind -- rest of course, I can just unilaterally declare myself to be AWOL and let the chips fall where they may. When on holiday this past summer, I got some able assistance from a couple of guys on the forum, plus it was summer and not that stressful. When the weather in Ireland gets to be partly cloudy for a week or two, as it can, then hardly anyone cares that much what the forecast is, they might come and read it, but they wouldn't worry about it much. I think in the new year I might start to look at restructuring this thread to bring in extra assistance on some routine basis, so I can let it go for a day or two every week. There are at least half a dozen forum regulars that I would feel comfortable working with on that basis, so if you suspect you're one of them, clear your inbox (or block it ).

Now I am wandering off to see what the 18z GFS has in mind and think about a forecast update in general. See you then.

smashey

Steve wrote: »

Moving on, keep up the great work MT, you're playing a stormer as we'd say in Ireland

Puntastic :pac:

Sonovagun

If people want to take my question as me being disrepectful to MT so be it! But at the end of the day it was just a question. I should have known people where going to twist it.

M.T. Cranium

Almost an Update _ Sunday, 2230h
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Even the most reliable guidance (like HIRLAM) is changing every three to six hours on small details. At the moment, I am left thinking that sea effect streamers are gaining in potential for east coast counties, while travelling lows to the south are weakening in potential for snow in the inland southeast -- but then if the streamers get particularly strong they can reach the inland southeast. This applies in particular to tomorrow for streamers and Tuesday for hit or miss coastal snow in the south.

So I don't consider this an update, just a reminder of a continuing series of slight or even moderate chances for snow, which would seem to include some fairly robust streamers now making landfall around Dublin. These are likely to keep going for several hours before dying out, then perhaps reloading on Monday.

It will certainly continue bitterly cold in most areas tonight with Ballyhaise already at -12 C and even colder in parts of Ulster.

The odds on the Christmas to 27th period having a warmup are about 50-50 but that's for any warmup including a partial one that only reaches the south. The most likely outcome in my view would be for bitter cold to try to hold on in the north all day 25th, with sleet or snow possible across parts of the south, then for these bands to move north on the 26th with rain likely in the southwest, followed by a gradual weakening of the fronts and a slow return to colder weather over a day or two. There is some potential here for a snowfall of quite large amounts if the front were both strong and slow-moving. This will become our prime focus, I think, as we approach Christmas Day.

Calibos

Sonovagun wrote: »

If people want to take my question as me being disrepectful to MT so be it! But at the end of the day it was just a question. I should have known people where going to twist it.

Well you could have phrased it a bit better. As it stands it reads like someone standing there with hands on hips and in a sarcastic voice saying, "So what happened to the big storm you predicted, Hmmmm??

A less ambiguous way of phrasing it while still being informal would have been, "Hey, MT, whatever happened to the Storm you predicted, is it still on, postponed...What happened to it?"

oterra

Calibos wrote: »

Well you could have phrased it a bit better. As it stands it reads like someone standing there with hands on hips and in a sarcastic voice saying, "So what happened to the big storm you predicted, Hmmmm??

A less ambiguous way of phrasing it while still being informal would have been, "Hey, MT, whatever happened to the Storm you predicted, is it still on, postponed...What happened to it?"

I dont think Sonovagun meant any disrespect in his tone but the question of course could have been structured differently considering the respect we all have fo MT in the Weather boards.
Maybe now would be a good time to draw a line in the sand and discuss whats important to the contributors and readers in here:o

PixelTrawler

Sonovagun wrote: »

Where's the snow storm you predicted?

A perfectly valid question (I fail to see how it could be interpreted as rude?). Be interesting to hear an analysis of what happened vs what was predicated as they seem quite out of kilter (in some regions).

Edit, not looking to further the "rudeness" thing, more interested in why the models get it so wrong kind of thing

Trogdor

This thread is for forecasts only, no bickering or arguments. Any off topic posts will be deleted without warning and people who repeatedly chose to post off topic posts here will ultimately be banned.
There is a cold spell discussion thread open where questions may be asked.

M.T. Cranium

Monday, 20 December, 2010
_____________________________

TODAY will continue very cold with scattered outbreaks of light snow in the east and southwest, rather cloudy through the southeast, widespread ice fog central and north slow to lift, allowing severe cold to continue in some places.

Highs will vary from about -6 C in ice fog, to -2 C under cloud, except closer to +3 C in far southwest where sleet or rain may mix in with snow.

Some chance of locally heavy snow streamers in the Dublin, Meath and north Wicklow coastal regions, although not starting until mid-morning or mid-day. Watch for updates.

TONIGHT will be partly cloudy and very cold with some pockets of severe cold in central and northern counties, locally, lows may fall once again to about -15 C with ice fog and icy roads, but a more widespread figure would be -10 C. Around the coasts, closer to -7 C but in the far south -2 C. Some snow developing and moving slowly east across the south. Potential for 3-6 cms snow. Streamers could continue in the east at times. Similar potential amounts.

TUESDAY, there is some risk of moderate or heavy snowfalls in the south, southeast and east. Watch for updates later today, as this situation continues to develop. Winds increasing there to ENE 15-25 mph. Further north, high cloud with some sunshine through patchy ice fog, highs ranging from -5 C north to -1 C south.

WEDNESDAY to FRIDAY are expected to remain very cold, with slight risks of snow in east and southeast each day, more chances for sunshine in west and north each day, and similar temperature ranges. The colder north, central and inland west will have lows of -15 to -10 C (and there is a risk of even more severe temperatures that could threaten all-time records over deeper snow). The east, southeast and south will be somewhat more cloudy in general but if it clears at all there, lows could also drop below -10 C locally; however, -6 C would be a more likely average. The daytime highs in general will remain below freezing to slightly above in a few south coast and west coast locations. Some scenarios give a risk of heavy snow or even sleet and freezing rain by Christmas Eve (evening).

SATURDAY (Christmas Day) will almost certainly be milder to some extent, but our forecast will not definitively change to anything beyond mixed sleety precipitation that could be rain in the southwest, sleet south central and west coast, ice or snow further north and east, with increasing southeast winds and temperatures rising to about 4 C south, 0 C north. Some range around that is quite possible, including a faster thaw, or a more stubborn cold regime with the potential for snow.

FURTHER OUTLOOK ... Some chance of a general thaw, we await a more definite set of signals ... there is a chance this thaw will be held back and even some risk of a snowstorm as the alternative outcome.

WEATHER FOR MTC TODAY was partly cloudy and a bit milder, highs near 6 or 7 C.

Sorry we're running a bit late, have had a lengthy computer virus cleanout that went longer than expected. Updates when and if possible, check the usual threads too.

djhaxman

trogdor wrote: »

This thread is for forecasts only, no bickering or arguments. Any off topic posts will be deleted without warning and people who repeatedly chose to post off topic posts here will ultimately be banned.
There is a cold spell discussion thread open where questions may be asked.

Why not make MT a weather forum moderator? It's basically his thread anyway, that way he can open and close the thread as he likes.

M.T. Cranium

It's okay, I think the situation is fine, a little chatter never hurt anyone. Got lots to do already no doubt, without being a moderator too. But once this active weather period ends, we'll have time to design some appropriate threads and keep the chat out of this thread.

Serenity now:

Speak Now

M.T......go to bed

M.T. Cranium

No worries, I am about to do just that ... looks like Dublin streamers are getting riled up and electrical, might be a sign that marginal situations are about to become snow producers rather than snow with-holders.

But I shall leave the details to the many weather forum regulars who seem to be on hand. Note my comment in chat thread about full moon setting in eclipse Tuesday morning, you'll need clear skies and a good view of the northwest horizon to see this but at a decent time, after 0700 (full moon at 0813 GMT, but best view probably closer to 0745 given the angles).

M.T. Cranium

UPDATE _ Monday, 8 p.m.
________________________

Adding these details to the existing forecast.

Locally heavy snow is likely to continue in some parts of Meath, Dublin and Wicklow with 10-20 cms more overnight in some places. Our discussion threads have the best details on when and where, also watch for renewed thundersnow around midnight especially.

This east coast activity may spread further inland at times and could begin to merge with weak outbreaks of light snow near the south coast later tonight. This merged activity could give highly variable amounts to the southeast, with local 5-10 cms possible but this will probably turn into a radar watch type event.

Also, some 2-5 cm snowfalls appear likely in Donegal and north Mayo overnight from hit or miss snow showers in weaker sea-effect streamers moving towards the southwest.

As the existing forecast says, tomorrow looks a bit more conducive to snow across the south at least on a sporadic basis, but east coast streamer activity could continue and there is some chance of this turning into a heavy sustained snowfall event lasting into Wednesday. Later updates may address this possibility. The model guidance is inconclusive on that, not ruling it out or making it too obvious either. (mothers don't let yer sons grow up to be forecasters ... )

All of the above suggests that bitterly cold night temperatures may get squeezed into smaller zones inland but these will likely continue the next few nights and the bitter cold could intensify before the spell terminates or fades out. On that question, no change in my thinking, I am seeing a lot of weaknesses in the rapid warming scenario for 25-26 Dec and would stress caution as this seems like less than a sure bet to me ... any outcome between a partial thaw and mixed precip, to sustained cold and possible snow, remain on the table. Some models led by the UKMO show this but also, the general climatology of this situation and past unhappy experiences of the forecasting world with stubborn cold hanging on would suggest caution. Of course, it could just go to a quick thaw, that remains a possible outcome. There are such mixed signals that it seems prudent to say that this rapid thaw is more or less of a toss-up.

A reminder that the Moon sets in total eclipse at around 0745 to 0815 Tuesday, for the few who might have clear skies at that time.

JJJJNR

Legend!

4gun

M.T do you think we will get any more snow in N Kerry in the next few days.....I want a white Christmas

M.T. Cranium

Tuesday, 21 December, 2010
______________________________

Moon is setting in eclipse that reaches totality around 0730 and peaks at 0817 (at which time Moon would be close to northwest horizon in western Ireland ... check it out if you have a patch of clear skies in that direction.)

ALERT for snow, with some areas of heavy snow including some thunder-snow, as well as a few heavy hail showers, in both western and eastern Ireland today, with these areas partially merging across the south later. Amounts will be highly variable as streamers are the main component in the east. Wicklow and north Wexford could continue to get more heavy snow and increase from current 10-15 cms to 25-30 cms or more. Dublin and Meath could increase from 5-10 cms in some parts to 10-20 (less where no cover yet). Inland southeast could start to see 5-10 cms, and south coast about 2-5 cms. Kerry and parts of west Limerick, west Cork, Clare and west Galway could see 5-15 cms, with some mixing to sleet near sea level. In all cases, some thunder-snow possible. Donegal, Mayo and east Ulster are on watch for possible later snow streamers. Also, ALERT for ice fog, widespread icy roads, severe cold in many central counties between the snowfall areas, readings of -12 to -15 C possible, ice fog not dissipating much in valleys.

TODAY ... Be sure to check the alerts above, because in this section, I will just summarize and say areas of snow in east, southeast, and southwest, also west Connacht. Otherwise, mostly cloudy, ice fog, severe cold. Some hazy sunshine in north at times. Highs generally -2 to -5 C. Check alerts section for snowfall amounts. Winds light in north, moderate NE across the southeast and moderate SSE near west coast. Watch for updates on snowfall distribution and amounts.

TONIGHT ... Snow may continue in the south and southeast, east, but less of a factor in the west, as clearing may spread that way. Severe cold elsewhere with ice fog and very icy roads. Lows -6 to -10 C on average but as low as -15 C in some clear spots.

WEDNESDAY ... Periods of snow still quite possible in southeast, otherwise, partly cloudy to sunny except for ice fog, very cold. Lows -6 to -12 C for most, -15 C or lower possible central and north. Highs -4 to -1 C. Winds fairly light but NE 10-20 mph at times.

THURSDAY ... Still could see the occasional snow streamer in east, flurries elsewhere, but mainly dry and cold with some sunshine, ice fog. See previous day for temperature ranges.

FRIDAY ... Continuing very cold with some light snow in east, southeast at times. Considerable sunshine further west and north. Temperatures continuing in similar range to previous two days or slightly colder for some places in early morning due to clear skies and very strong high pressure.

CHRISTMAS DAY (Saturday) ... Bitterly cold to start, clear and cold in some northern areas, clouding over across south, west, raw southeast winds, risk of snow developing, could change to sleet or freezing rain late in day in the southwest. Temperatures slowly rising from well below freezing to near or slightly above freezing.

SUNDAY (St. Stephen's Day) ... This is still very much of a puzzler with the models ranging from snow to cold and dry to sleet, fog, rain ... so what to believe? ... placing my marker on snow mixing with sleet for now. We'll keep a close watch on this. Potentially, it could warm up considerably in southwest but stay very cold in Ulster, with bands of mixed precip in between. That would involve a lot of bad weather, fog, ice and snow, also thawing and flooding in some areas. But it may not get that mild so the results may be more along the lines of a snowfall event.

OUTLOOK ... If it does turn milder, it will be brief and not very mild before cold air returns from the east before New Years. It could conceivably never get much milder than 2-4 C before that happens.

MTC's WEATHER TODAY ... (Mon 20 Dec) ... Cloudy, cool, sleet at times but not much accumulation, highs near 4 C and winds ESE 20-30 mph.

WX HIGHLIGHTS ... Snow across northern plains states, rather cold north and east of that, but quite mild in the central plains, 15-20 C in some places.

Watch for updates both here and in discussion threads.

M.T. Cranium

UPDATE _ Tuesday, 6 p.m.
_______________________

The large-scale forecast remains valid ... here are some updated details.

The heavy snowfall ALERT remains in place for Dublin, Wicklow and parts of MEATH and is extended to significant snow in Kildare, Carlow, Wexford and possibly parts of Louth, Laois, Tipps, Kilkenny, Waterford. Further snowfall amounts now into Wednesday (and possibly Thursday in some cases) could easily double existing snowfalls, and bring additional 20-40 cms of snow to some parts of this region. For the counties being added to the alert, new amounts of 5-15 cms likely and 10-20 cms possible. Coverage may not be complete with gaps in the snowfall as it moves further inland. Some flurries may develop further inland and in parts of Ulster where 2-5 cms could fall in some eastern counties eventually.

Meanwhile, the southwest (mainly inland Kerry and west Cork) may continue to see a few more centimetres of snow but this area is slowly degrading and seems likely to pull out to sea (southeastward) fairly soon -- city of Cork may escape this snowfall -- but eventually there could be further activity from the eastern source spreading that way in the next 36 hours, amounts likely to be small.

Most other parts of the existing forecast still valid, my thoughts on Christmas Day and the two or three days afterwards have not really changed and I honestly don't think the models have that much of a handle on the situation yet, so I am reluctant to keep changing with them until I see better indications of a real trend. It makes sense to me that temperatures would rise at least slightly for 2-4 days some time between Christmas and New Years Eve then fall back in the new year with renewed blocking and the additional influence of very cold air masses moving west through northern Europe. The chances of a very significant thaw and even flooding have to be considered but I'm not ready to declare this "on" at this time.

Watch for further updates as required.

M.T. Cranium

UPDATE _ Tuesday, 10:30 p.m.
___________________________

No big changes in the existing forecast ... somewhat milder air has made it ashore in Dublin yet at any time the regional land breeze could push back into the mix and this could set off thunder-snow, particularly well after midnight towards 0300h perhaps. Snowfall rates could become quite prodigious were that to happen. I think our existing forecast and alert issued earlier would remain valid but some places will get less, some more than the range being mentioned. The inland progress of the snow appears to be slow but steady and parts of Tipps and Waterford may be seeing slight accumulations later on.

I continue to foresee periods of accumulating snow at any time almost right up to Thursday afternoon when a general clearing is likely due to stronger high pressure. Thursday night could be very cold in areas that have only seen moderate cold so far, as a result.

The other main question is the sequence of events after Christmas, because it now appears more settled that Christmas Day will be cold and dry, with perhaps some snow breaking out later in the day in the south and west mainly. The latest guidance from the 18z GFS, not always the forecaster's favourite (you may know that we call it the pub run) is increasingly resistant to any real warming. The cold high stays very near to the North Sea throughout the period where warmer air is trying to move east, and this is reinforcing my belief that cold air could hang on for a long time despite some advance of milder air into perhaps Kerry and nearby parts of other counties during the night of 26-27 December. I'm afraid this is a perfect recipe for outbreaks of every type of precipitation, ranging from heavy snow to ice pellets, sleet, freezing rain and cold rain which as we all know by now is just freezing rain under a different name for its similar impact on roads and pavements.

Therefore, the only real certainty is uncertainty. I could add some even more obscure efforts but the long and short of it is that one might want to count on very inclement weather hanging on for days as the milder air tries, perhaps with limited success, to move in.

Tae laidir

'The chances of a very significant thaw and even flooding have to be considered but I'm not ready to declare this "on" at this time.'


Significant thaw (or snow) is not a phenomenon we are used to, and I am sure you have experience in Canada. Given the large amount of snow about, including the unmelted snow from earlier in the month on the Wicklow Mountains, what type of temperatures, timeframes & rainfall amounts should we be watching out for?

BlancheSparks

Can you put more detail in about south west. We have just had 8" of snow here in South Kerry.... I was just about to set out for town(15 miles) today because the roads had improved, and I need supplies. I looked at the sky to the North west and it was obviously snowing in the distance. Fortunately I didnt go or I would have stuck there. It snowed all day.
Will I be able to get out of here on 26th do you think, to travel up to Kilkenny?
Not really moaning, I really look forward to your forecasts.:o

M.T. Cranium

Wednesday, 22 December, 2010
_________________________________

TODAY ... While snow has largely ended over the southeast as of 0630h, there remains potential for it to resume at times by late morning and afternoon, in a few streamers coming inland from Meath south to Wexford. Some further snowfalls then may be anticipated but amounts may be much less than yesterday. Watch for updates with estimates of new snowfall amounts. Otherwise, most of the country will have clear to partly cloudy skies over top of any layers of low-level cloud and ice fog, and the sun should break through in most places from time to time. Very cold for most with highs only -5 to -1 C (possibly a bit higher near east coast if streamers develeop). Winds will increase somewhat to NE 15-25 mph in exposed areas although central valleys will remain mostly calm. A few flurries giving 2-3 cms could hit parts of Donegal and north Mayo also.

TONIGHT ... Generally clear and very cold with widespread ice fog, but northwest counties will be cloudy with a few periods of light snow, and some streamers may still be active near Dublin and Wicklow. Lows will once again be well down into the -10 to -15 C range except where winds are onshore, and there closer to -5 C.

THURSDAY ... A weak trough may bring scattered flurries near north and east facing coasts, and otherwise partly cloudy with some sunny intervals, quite cold again with highs generally -4 to +1 C.

FRIDAY ... Early morning severe cold, possibly reaching -18 C over snow fields and -12 C even out towards the coast in some areas. Widespread ice fog likely, that may not clear all day in some places. Weak sunshine for other regions. A stray flurry possible, but largely dry. Highs -7 to -2 C.

SATURDAY, CHRISTMAS DAY ... For Ulster, Connacht, Leinster and east Munster, expect a dry start with some sunshine in the morning, extremely cold inland, some ice fog; by afternoon, cloudy, some light snow possible as winds pick up to SE 15-25 mph. Morning lows about -12 C to -7 C and afternoon highs -3 C to +2 C ... for West Munster, cloudy with outbreaks of light snow or sleet, possibly becoming rather heavy at times, morning lows about -8 C around midnight, highs reaching -2 to +4 C. Winds increasing to SE 20-35 mph.

SUNDAY, ST STEPHEN'S DAY ... Cloudy, some fog or ice fog, snow in parts of Ulster, Leinster, inland Connacht, freezing rain a risk for later in central counties, possibly turning to a cold rain in south and southwest. Temperatures slowly rising all day and could reach +1 C in Ulster, +3 C central and +7 C southwest. Winds SSE 20-40 mph. There remains some risk that this forecast, based on current model consensus, might change to more of a cold/snow scenario in general. Watch for updates.

MONDAY 27th ... Possibly milder with some thaw conditions in west and south. Heavier snow fields in Connacht and Leinster not likely to thaw or melt very quickly but this could lead to fog and widespread slushy conditions. Once again, this is perhaps 70% likely, the other 30% chance would involve less warmth and something like sleet or wet snow hanging on. But for now, we'll go with a general temperature range of about 3-7 C east and north to 6-9 C south and west.

OUTLOOK ... A few more relatively mild days should lead to clearer roads and pavements, with any luck, and slow melting of lying snow. There would be some light rainfalls, possibly sleet or wet snow over north on higher terrain, and highs generally in the 5-8 C range. This is likely to end some time around the New Year with another cold outbreak from either the northeast or the north to northwest. Details should be clearer by about the 27th on that next cold spell.

MTC's local weather ... Cloudy here on Tuesday 21st, some light rain by this evening, and a bit milder with high of 8 C.

WX HIGHLIGHTS ... A severe storm hit eastern Canada, this being the one being tracked across the Atlantic for possible warming trends over the holidays. The effects in Nova Scotia, PEI and New Brunswick were mostly rain and strong east winds with storm surges in places due to the full moon high tides and wind action. California has had torrential rains and mountain snows, and so has New South Wales in Australia. The snow there is at high elevations in the mountains east of Canberra. It's probably above 20 deg C in the big cities but this is rather cool for Australia in what amounts to June down under.

M.T. Cranium

UPDATE _ Wednesday, 6:30 p.m.
____________________________

No significant changes to forecast. A few parts of south Dublin and north Wicklow have seen (from reports on boards) 5-10 cms of snow in relatively weak streamers today, and these could continue but will only impact a few places close to the coast, it seems. All the previous forecast comments about severe cold spreading due to high pressure, and the uncertainty of the degree of warmth to follow any partial or complete breakdown (speaking of the weather here, not the forecaster), remain untouched by later model runs.

I could note that the GFS and GEM models continue to be fairly bulllish on warming by late 26th and 27th, whereas the UKMO model sticks to its earlier almost-no-warming-at-all scenario. The ECM, and this may tell the actual story, is slowly backing off its agreement with the milder solutions although has not yet backed down to the extent of the UKMO. The German GME model had been somewhat cold-biased too, and is now closer to the ECM. The wise forecaster, confronted with this array of guidance, would normally apply for several days off.

As I have only myself to consult on that, I will stick with it, even providing at least a daily update through the holiday period, and it's my hope that these relatively quiet if bitterly cold conditions give everyone a better chance to complete their holiday travel plans and be where you need to be and want to be. That will not be a problem here, as it has turned quite mild, and in any case, our version of Christmas was planned to be right here for a change, no long road trip to the beautiful scenery I posted earlier. Maybe in January some time.

ch750536

I cant see the warming that was forecast previously, it is really cold here, a southerly for a day isn't going to solve this. Was looking at the road temps earlier, no difference between surface, 30cm & 50cm, speaks volumes (well a small %age difference).
I think the high will hold and the ice is here for another week at least.

M.T. Cranium

Thursday, 23 December, 2010
__________________________________

Very cold weather will continue until about the end of the night between Christmas and St Stephen's Day. Then it will gradually be replaced by somewhat milder weather but with rather messy results. Readers should be aware that there is major uncertainty in the forecast because all the various models give totally different outcomes after five days, which range from the cold hanging on and deflecting the push of milder air, to an all-out onslaught of very mild, wet weather that would thaw all the snow. My personal hunch (and this is confirmed to some extent by my research) is that the cold will prove more difficult to move than most models are showing tonight. But I will give you some probabilities of different outcomes in the extended range. There is much better agreement on the first three days.

TODAY ... Snow showers, heavy in a few places, will continue in coastal parts of Meath, Dublin and Wicklow, as well as a few parts of Wexford. Later, one or two of these could make longer forays inland. Amounts will be highly variable but mostly between 5 and 20 cms. However, almost all of the country outside of that small area (with many people) will be dry with considerable sunshine once any ice fog dissipates (which it may not do everywhere). Highs therefore will range from about -6 C in ice fog to -3 C in sunshine and possibly -1 C near the coasts where winds may be stronger from the northeast at 15-30 mph at times.

TONIGHT ... Widespread clearing, snow showers becoming just light flurries then ending on the east coast, and exceptionally cold in many places, with lows reaching -15 C and possibly lower over large sections of Ireland, -10 to -12 C closer to south coast and east coast, and along the outer north coast about -5 C. It would not surprise me if a few traditional cold spots flirted with the -20 C mark. Some ice fog by midnight and dense ice fog widespread by morning. (notice I've given up saying icy roads, I'm sure everyone has adjusted by now)

FRIDAY ... Sunny and very cold in most areas, some cloud and flurries could graze the east coast at times, winds light northerly, highs only -7 to -3 C for most places, and considerable ice fog remaining all day inland valleys.

FRIDAY NIGHT (Christmas Eve) ... Clear and very cold again, although some patchy cloud could develop and hold temperatures a few degrees higher than previous night. Lows therefore more variable but in the -5 to -15 C range mostly. Calm, good sleighing weather for reindeer.

SATURDAY (Christmas Day) ... Some sunshine at first although widespread ice fog too, cloud overspreading the southwest, west and northwest by morning and further east by evening. Some light snow or freezing drizzle possible in a few spots. Mostly dry but some ice fog too, highs -4 to -1 C on average, except 2-4 C in southwest by evening.

SUNDAY (St Stephen's Day) ... Early morning fog, freezing fog, snow mixed with freezing drizzle becoming heavy in some areas, freezing rain possible, and about a 50% chance of much milder rainy weather in the southwest, which would likely be accompanied by dense fog and strong SSE winds. If the cold hangs on, highs could be largely held down to 2-5 C. If the mild air wins more easily, highs could get into the 7-10 C range southwest and 3-7 C elsewhere.

MONDAY-TUESDAY ... The most likely outcome (60% chance) would be slightly milder weather with a lot of fog, rather gusty south winds, slow melting of snow but widespread slush and slippery conditions, with pockets of very dense fog in valleys (even some ice fog). Highs in this scenario would average 5-8 C (it could be milder, but the melting snow and fog will hold down the temperatures somewhat). Two less likely outcomes can be mentioned here at this range -- (20% chance) very mild, heavy rain, fast thaw and melting, flood potential or (20% chance) staying cold, further snow or freezing drizzle, or even a return to wintry sunshine.

Obviously there is little point in trying to extend this forecast although for various reasons I think it's probably more certain that whatever happens in this period, it will revert to very cold weather soon after New Years.

MTC's LOCAL WEATHER TODAY -- It was cloudy, mild and showery at times, almost spring-like except for the rather dark look to the day, and highs of 9 or 10 C. This seems likely to continue for several days.

WX HIGHLIGHTS -- Cold in the eastern half of North America except in eastern provinces of Canada near the Atlantic where quite mild and wet.

This may concern a few travellers -- snow may break out today around Paris, Brussels and Amsterdam. Expect a few delays if heading there.

Trogdor

Posts moved to discussion thread, this thread is for forecasts.

M.T. Cranium

UPDATE _ Thursday, 1800h GMT
___________________________

Forecast remains valid but some updates on the local east coast snowfall (and yes, I saw the brief foray of snow through the inland southeast on radar loop) ... this will continue about six more hours now, tapering off to very light flurries well after midnight. A further 10-20 cms possible in Dublin and parts of Wicklow and Meath. A further 5 cms possible in Wexford.

While there are no absolute guarantees, I am fairly confident that new snow will not be a problem (on any significant scale) tomorrow, since the pressure gradient will fall off to almost nil under strong high pressure scheduled to take up residence over central Ireland. The main weather features tomorrow will be the intense cold and widespread freezing fog likely to persist under these nearly calm conditions.

I hope to update again around 2030h with regard to latest guidance for Sunday-Monday which so far (with some guidance yet to update) have the same scatter of outcomes, but from what I'm seeing, it would be wise to plan around travel disruptions from snow, sleet and ice (some freezing rain) on Saturday night and Sunday, and widespread problems with standing water, dense fog and localized flooding on Monday. This localized flooding would not hit all northern and eastern regions at once, it will take days to melt the snow packs there. Kerry, on the other hand, would be first in line for rapid snow melt, followed by western parts of Galway and Mayo. The further east, inland or "up higher" you are, the slower this process would be, to the point of being almost a non-factor in higher parts of the southeast.

More updates on that period to follow.

sboyle

hi can you tell me if waterford will see any snow tonight?

Speak Now

sboyle wrote: »

hi can you tell me if waterford will see any snow tonight?

That's an easy one...no.

M.T. Cranium

UPDATE (2) _ Thursday, 2030h
___________________________

Anybody know the location of the keys to the Dublin snow machine? Thanks.

I had promised an update on the weather after Christmas, and here it is ... what's already posted above and previously continues to be my forecast offering (probably more of the myrrh and frankincense than the gold, but, I had considerable travel expenses along the way ...)

Let me review the various models: :eek::eek::mad::pac::p:o

Okay, now in words. ECM somewhat backing off major warming and quick transition to cold inversion high set-up that would see a partial thaw followed by more ice towards New Years. GFS still wanting to thaw and stay mild for a while although nothing too dramatic. GEM the mildest of the lot, will either hit a home run or strike out swinging (sorry, wrong sport but you'll know what I mean). NOGAPS is similar but less extreme. UKMO has finally moved from its stubborn no-warming stance to a slight warming that would probably not thaw counties away from the west coast. GME a little of everything now. JMA suggests a slow thaw followed by a slow freeze -- could be the best of the lot, at least it's close to the mean. Moscow model (on meteociel) has the warm front stalling south of Ireland suggesting days of snow. If correct, a coup for this lightly regarded newcomer. The Australian model (BOM) which had been cold is now like the GFS.

I continue to be very suspicious of the warming trend and will believe it when I see it -- however, just on the probabilities from this mysterious melange of models (even Aunt Lottie's trifle will be easier to figure out than this), could suggest that the sequence is most likely to be:

Christmas Day -- cold and dry, some late outbreaks of snow west

St Stephen's Day -- cold and wet, snow changing to freezing rain for most, sleet and later rain in southwest, very foggy and icy especially east.

Monday 27th -- thaw conditions setting in but perhaps not in Ulster, parts of Leinster, deeper valleys in east Munster, more risk of fast thaw to flooding in Kerry, west Cork, Galway and Mayo (Clare, Limerick, east Cork less so due to absence of deep snow).

Tuesday 28th -- thaw diminishing slowly, but some risk of a heavy cold rain, roads very much of a mess with ponded meltwater and slush (or possibly ice if colder).

29th to New Years Day -- quite likely a return to colder weather, possibly not too severe but back to freezing conditions at least at night.

I apologize for the vagueness of this scenario and I caution that it represents the sort of balance point between scenarios that involve a lot of rain and a lot of snow if one of the more extreme solutions verify.

The one good thing, I suppose, is that many people would already have planned to be at home or on a long-stay visit through the worst of this period, but for those who were planning to travel 26th or 27th, would just say, try to change that if possible because the odds do not look good for easy travel of any kind (unless very short trips).

And a word to the wise in the snow zone, shovel and clear tomorrow because you probably won't want to be out on Christmas Day and then later, you could be facing an icy, slushy mess with the risk of injuries to pedestrians using your property or the pavement outside your home.

M.T. Cranium

Friday, 24 December, 2010
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TODAY ... With the exception of some freezing fog well inland in a few valleys, widespread very cold sunshine today with highs generally -5 to -1 C. There is the slight chance of a flurry in Wexford from mainly offshore streamers moving closer to the coast. Winds generally very light to calm.

TONIGHT ... Another clear, very cold night, with more widespread freezing fog due to a stronger inversion. Lows about the same as the past night, in the range of -15 to -10 C for many places and even -5 C in temperate coastal locations.

SATURDAY (Christmas Day) ... Morning sunshine giving way to cloud, but many inland counties will experience persistent freezing fog. Highs about -2 C on average east and north, to +3 C south and west. Some light snow or sleet is possible by evening or midnight in the southwest (inland). Winds will be calm to start but a raw SE 10-20 mph later. Risk of a streamer developing overnight (26-27) in the Irish Sea and hitting perhaps Down, Louth and nearby counties.

SUNDAY (St Stephen's Day) ... Cloudy, intervals of snow, sleet, freezing drizzle, freezing rain, followed by rain. The main forecast question is whether these wintry types will be heavy or persistent. This may prove to be the case in some parts of Ulster and Leinster. A faster transition can be expected in most of Munster and coastal Connacht. Ice fog could be persistent inland turning to fog as temperatures slowly rise. In general, morning lows will be in the range of -2 to +4 C from east to west, while highs will be 3 to 8 C from east to west (possibly a pleasant 10 C in coastal Kerry). Dense fog will develop in many areas by afternoon and evening as winds rise to SSE 25-45 mph in the west, SE 15-30 mph in the east. There remains a slight chance of the fronts stalling and for snow to continue -- watch for later forecasts just in case this happens.

Thaw conditions will set in slowly for the east and north as well as for heavily snow-covered parts of inland Connacht. Thaw conditions will be faster to develop in Munster, in part because some areas may not have snow cover, but where there is some in the west, this may melt rapidly leading to local flooding and mudslide problems in hilly areas of Kerry and west Cork.

MONDAY (27th) ... Unless the model guidance proves entirely false, this should be the mildest day of this brief thaw, and with 10-15 mms of rain in some areas, could prove to be quite a wet day as snow begins to melt. With lots of snow still in place, ponding on roadways and in parking lots will be a problem in many areas. So will dense fog in rural areas. Highs may reach 7-10 C in most areas but 4-7 C over higher northern snow-covered areas.

OUTLOOK ... Higher pressure will rapidly build in from sources in the North Atlantic and Scandinavia. While this won't be a severe cold spell, if at least half the snow survives the thaw, the nights are likely to become very cold again, and some inversion fog will develop and remain in place all day inland. Expect highs around 3-5 C at maximum, possibly lower inland, and overnight lows in the -5 C range. This spell may last quite a while according to the models but there are also hints of a reload of severe winter weather, which you could estimate might return some time around 2-4 January or perhaps a bit later than that.

MTC's LOCAL WEATHER -- Thursday Dec 23 was a mild, cloudy day with some rain and moderate SE winds here.

WX HIGHLIGHTS -- It remains cold across eastern North America, and a minor snowstorm is expected by the 26th-27th in the mid-Atlantic states. This may miss NYC and New England to the south.

Due to the Christmas holiday, updates might not appear but some of the weather forum regulars will probably be on line at various times on the discussion threads. If we don't meet in cyberspace again, Happy Christmas to you and yours, and safe travels.

M.T. Cranium

Saturday, 25 December, 2010
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Forecast essentially unchanged ... have a Happy Christmas and if you're travelling, safe journeys. The forecast in brief summary:

TODAY: Cold, dry, increasing cloud from west to east, winds picking up by afternoon or evening in the west, from a southerly direction. Highs generally about -2 to +3 C.

TONIGHT: Chance of snow, sleet or freezing drizzle in the east and north, foggy with rain developing west and south, temperatures slowly rising.

SUNDAY: Foggy with rain leading to a slow thaw in some areas, continuing wintry mix in some eastern counties at first, temperatures continuing to rise slowly, extensive ponding of water and slush by afternoon/evening. See the thread on thaw and flooding for more details. Highs around 6 C east and around 10 C southwest, 8 C inland west.

MONDAY: Mild, periods of rain, thaw with some flooding problems. Not all the snow will melt, especially on higher terrain. Highs near 9 or 10 C. Foggy.

TUESDAY: Still rather mild, foggy, some hazy sun may break through, highs around 6 C.

OUTLOOK: Dry and cold again, not severely cold at least for a few days, but well below freezing at night.

I think that's more than enough for the Christmas morning brain to absorb, don't you? I'll know soon enough. ... My weather on Friday 24th was very mild, windy, with highs near 10 C in rain. This is set to continue "today."

Travelling to the states? You may run into snow in NYC by Sunday night or Monday morning. This storm is just getting started now in the southeast U.S. but looks set to become stronger by Sunday. Amounts may be 3-6" for NYC and heavier to the east in Long Island and eastern New England. Washington DC and Philadelphia could see about 2-4" with heavier amounts to their east as well.

I would advise people to check the thaw and possible flood risk thread for updates from the weather forum crew, as I will very likely be out of the "office" until about this time Sunday morning for an update then.

M.T. Cranium

Sunday, 26 December, 2010
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TODAY ... Milder with periods of rain in the western half of the country, although this rain is edging east rather slowly, winds increasing to SSE 20-40 mph ... highs about 8-10 C with the rain, and a substantial thaw likely with some flooding ... further east, cloudy and a bit milder today with risk of brief intervals of snow, sleet or freezing rain, mainly by mid-day or afternoon, especially over inland valleys that have retained sub-freezing temperatures to this morning ... here, these wintry precip types will change slowly to drizzle or rain this afternoon or evening ... and highs will stall at about 3-6 C.

TONIGHT ... Dense fog developing with widespread rain and thaw conditions, some flooding likely from snow melt as well as 10-15 mms of rain, lows about 3 to 6 C in most areas (near zero in parts of the northeast).

MONDAY ... Rather mild with fog and rain becoming showery by afternoon, highs about 9-11 C, extensive thaw and possible flooding. Winds S 15-30 mph and patchy dense fog especially inland over melting snow. Widespread road flooding from ponded meltwater and melting slush.

TUESDAY ... Drizzle, foggy, not as mild with lows near 2 C and highs near 7 C.
However, thaw and some melting will continue to be problems. Poor road conditions in some areas.

OUTLOOK ... Dry and colder for several days, see discussion threads for more about this, seems to me that temperatures will be slightly below normal again.

MTC's WEATHER TODAY (25th) was mild with rain, highs near 11 C. A snowstorm is brewing for the east coast of the U.S. and amounts of about 8 to 15 inches are predicted for the large cities, possibly more in some places.
This will reach its peak tonight and early Monday.

Staying on a somewhat reduced schedule through today, would advise that you check the ongoing threads in the weather forum for more timely updates by this afternoon, and travel with caution in Kerry and parts of west Connacht where the thaw will be underway today, the main hazard may be local mudslides from rapid snowmelt at mid-range elevations where snow is deeper, and/or ditches and culverts flooding rural roads. So far, it does not appear that freezing rain will be an enormous problem but locally it could be severe, depending on when rain starts and how much cold air is left trapped near the surface. I am only expecting snow in a few inland parts of Leinster and Ulster, briefly, but watch for any possible outbreaks from sea effect streamers that could form in a south to southeast wind near Down and Louth later on.

M.T. Cranium

Monday, 27 December, 2010
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TODAY ... Foggy and mild with rain becoming showery, some brief intervals of hazy sunshine in south by mid-day, winds SSW 20-40 mph falling off by late afternoon to 15-25 mph. Highs 8-11 C. Extensive melting of snow, local flooding and widespread ponding of water in areas currently snow-covered.

TONIGHT ... Foggy and mild, periods of rain in western counties, winds staying southerly at 15-25 mph, lows 3-7 C (milder in southwest than elsewhere). Further melting of snow and flooding problems. Localized rainfalls of 15-30 mms western counties.

TUESDAY ... Rain moving north into Connacht, 10-20 mms, drizzly light rain elsewhere, continued rather mild in a moderate southerly breeze, highs 7-9 C. Fog will tend to thicken by afternoon and evening. Some continued flooding problems. Note that higher elevation snowpacks will be quite unstable and prone to local snow slides. I expect by this point, there will be little snow left below 300 metres above sea level, except in wooded areas.

WEDNESDAY ... Foggy and rather chilly again, with morning lows near freezing and afternoon highs of 4-7 C, in light southeast winds.

OUTLOOK ... Several days of cool, almost calm weather with widespread fog and mist, some sunshine possible around coasts mainly, and temperatures near -3 C at night, near +4 C daytime on average. This spell seems likely to last through New Years. Most models are showing a period of somewhat chilly northwesterly flow early in 2011 but we have to watch for more retrogression which could open the way to colder arctic air to return at some point.

MTC's LOCAL WEATHER for Sunday 26th was cloudy and mild with slight rainfalls and highs near 10 C.

WX HIGHLIGHTS ... A blizzard developed earlier Sunday on the east coast and has paralyzed New York, Boston and areas in between. Not so bad further south around DC where the snow has pretty much ended with only a few inches, but NYC, Long Island and parts of New England are getting at least 30 cms and up to 60 cms of snow in very strong northerly winds gusting at times to about 60 mph. Expect long delays at New York airports which are likely to be closed most of today.