Prolonged cold spell on the way

jambofc

maquiladora wrote: »

Nice 0Z models this morning.

But until we are 48-72 hours out then I'm not changing my mind. I'm still not optimistic of snow at low levels because there is still more than enough time for reality to look very different to what the models show.

baa humbug

have to agree(thats why ive been so quiet) the charts these days just dont seem to be reliable anymore after 48-72hrs,been let down to many times,but this is getting closer and things really do like going our way this time....

maquiladora

In case anyone missed it, this is from MT's latest forecast for Thursday to Monday :

widespread snow showers are likely with just some mixing to sleet or rain very close to sea level and due to the warmer sea temperatures ... accumulations of snow are likely, it's probably too early to speculate but at this point I would say 2-5 cms might be the sort of range at times

Speak Now

ScallowayLass wrote: »

I've got my fingers crossed, I live in the Shetland Isles and we have heavy snow forecast for later in the week! Here's hoping;)
Last year we had a snow fall around each full moon from November to March and it froze for the rest of the time, paradise for anyone who loves the snow (as I do).

Scalloway You've got some right dumpings over the years up there.

ScallowayLass

By dumpings I guess you mean snow
Yeah, first year I lived here I couldn't believe it! Never seen much more than a dusting for a day or 2 in Sligo, here, we usually get a right couple of weeks of snow usually arounf February but the last 2 years has seen a lot more heavy snows throughout the winter.

Deep Easterly

Looking slightly more encouraging alright for this coming weekend on the ECMWF:






Showers in the north and east; drier but much colder in the west and south. Awaiting the downgrades already!

WolfeIRE

maquiladora wrote: »

In case anyone missed it, this is from MT's latest forecast for Thursday to Monday :

widespread snow showers are likely with just some mixing to sleet or rain very close to sea level and due to the warmer sea temperatures ... accumulations of snow are likely, it's probably too early to speculate but at this point I would say 2-5 cms might be the sort of range at times

snow a possibility later this week for areas north of this line. This line will change with each run so don's lose hope if you are south of it.

I feel that the latest ecms bode well for more widespread snow showers come the end of the week and most if not all of the country will be at risk of seeing some snow.

I feel that higher ground, 150-200asl, have the greatest chance of seeing snow accumulating in any of the heavier showers.

maquiladora

06Z GFS looks fine to me out to 120 hours. So no real downgrade on that model in the near/medium term at least.

roryc1

-10 t850 starting around +129 hours so still looking good for sat(for some that is)

maquiladora

roryc1 wrote: »

-10 t850 starting around +129 hours so still looking good for sat(for some that is)

Doesn't last long but that will likely chop/change well before we get there.

General -8 / -9 everywhere out to 156 hours now. So no downgrade there from the 0Z. This is all FI territory now and anyway.

alfa beta

outlook on te met.ie site this morning looks a bit bland - showers are mentioned but none with the 'wintry' precursor much beloved by the folk at ME.

still, here' hoping MT is right and the guys and girls at glasnevin hill are just downplaying things til we're closer to the time.

maquiladora

06Z GFS starts the breakdown from the northwest around 250 hours with a low tumbling down over the high. Long way off and total FI of course.

maquiladora

Despite -10 uppers....



...the GFS snow/rainfall chart on weatheronline has the Irish Sea showers falling as rain, not snow, as they meet the east coast at 138 hours....



NAE snow/rainfall chart will be better as we get closer to the weekend but for the moment the above shows one of the reasons why I'm still not too optimistic about snow in this cold spell.

I just want the cold to last for a few weeks until things really cool down and then maybe we'll get something special before Xmas. :rolleyes:

Su Campu

Just to reiterate, even the man himself MT isn't going for snow at the lowest levels this week. There was always going to be some on hills and mountains, but for the vast majority of the population, I think sleety rain is the best they can hope for.

It remains to be seen what the weekend has in store. The latest ECMWF posted above has minimum about -8 850s, and it's a pity we can't see other parameters, like we can with the GFS. Met Éireann can, however, and therefore they feel these parameters don't add up to enough to warrant issuing snow forecasts yet. As discussed last night, the GFS is more than likely posting a snowier picture than reality will yield come the time.

The UK, as in most cases, is much more in line for low-level snow, so don't get led astray by Sky News or the Daily Telegraph, etc.

maquiladora

maquiladora wrote: »

Despite -10 uppers....



...the GFS snow/rainfall chart on weatheronline has the Irish Sea showers falling as rain, not snow, as they meet the east coast at 138 hours....



NAE snow/rainfall chart will be better as we get closer to the weekend but for the moment the above shows one of the reasons why I'm still not too optimistic about snow in this cold spell.

I just want the cold to last for a few weeks until things really cool down and then maybe we'll get something special before Xmas. :rolleyes:

The ridiculousness of those maps is underlined by the fact that snow out a sea turns to rain upon hitting the land.

In otherwords the Earth is square not round and the sun revolves around us not us around it :rolleyes:

In otherwords,they are inaccurate rubbish.

Rebelbrowser

The Beeb monthly outlook is out, see below (it's not too shabby either) -

Published at 10:00, 22 November
(Next update at 10:00, 29 November)
Written by Peter Gibbs

Summary

Weather roadblock

Weather patterns that affect the British Isles tend to fall into one of two broad groups, known to meteorologists as mobile westerly or blocked.
When the jet stream is screaming across the Atlantic, hurling depressions our way from the eastern seaboard of America, that's a mobile westerly. It's characterised by windy, wet but relatively mild autumn weather.
When the jet stream starts to meander, the weather becomes more lethargic. High pressure builds to the west of the UK, acting as a barrier to Atlantic storms and hence the term "blocked". This normally leads to winds turning to the north or east, bringing cold weather our way.
That's the pattern that will dominate our weather during at least the early part of this outlook. Once a block is in place, it often proves difficult to shift.

Monday 22 November 2010 to Sunday 28 November 2010
Cold and colder

As winds back round from east to north, so the feed of air becomes colder, originating in the Arctic.
Widespread sharp frost develops under clear skies overnight, as temperatures fall well below freezing.
The snow risk gradually increases as the colder air moves southwards. Areas exposed to the north to northeasterly winds are most likely to see significant falls of snow, especially over higher ground.

Monday 29 November 2010 to Sunday 5 December 2010
Wintry spell continues

The cold or very cold conditions are likely to continue into the first week of December, with widespread overnight frost and the risk of icy surfaces and further snowfall, particularly in eastern parts.
There is then a chance that southern and southwestern areas may turn a little less cold but also more unsettled as rain, sleet and snow tries to push up from the south, but the extent and speed of this encroachment will be open to doubt.


Monday 6 December 2010 to Sunday 19 December 2010
Confidence is high that temperatures stay low

The cold or very cold conditions are likely to continue, with precipitation amounts generally close to average, giving the risk of sleet and snow at times in many areas. However, sheltered western areas may be drier than normal.
There is a continuing signal for below or well below average temperatures, with widespread overnight frost, locally severe. There is a small chance of it turning less cold at times, particularly for southern and southwestern parts, but still with the risk of further rain, sleet and snow here.

Next week

Will the block give way, or will wintry weather prevail? Find out next week.

darkman2

The parameters for snow are comfortably met Friday onward. There should be snow at all levels by then. Could be a flake or two early Thursday morning in the East aswell. Don't forget the very cold frosty nights have started....it's a slippery slope from here on in!

ninebeanrows

Su Campu wrote: »

Just to reiterate, even the man himself MT isn't going for snow at the lowest levels this week. There was always going to be some on hills and mountains, but for the vast majority of the population, I think sleety rain is the best they can hope for.

It remains to be seen what the weekend has in store. The latest ECMWF posted above has minimum about -8 850s, and it's a pity we can't see other parameters, like we can with the GFS. Met Éireann can, however, and therefore they feel these parameters don't add up to enough to warrant issuing snow forecasts yet. As discussed last night, the GFS is more than likely posting a snowier picture than reality will yield come the time.

The UK, as in most cases, is much more in line for low-level snow, so don't get led astray by Sky News or the Daily Telegraph, etc.

Nobody was really saying we'd see snow this mid-week though were they?

What looks the case as i explained yesterday is this two phase scenario.

Harsh frosts, then first pulse of mod cold arriving Wednesday, Harsh frost Wednesday night, very cold day on Thursday with light NE winds. Some hail/rain/sleet showers possible for east perhaps some snow on hills for a time.

Friday is change day as shortwave pushes down UK east coast and falls towards Netherlands. It will becoming briefly less cool with widespread showers some wintry. Harsh frost & Ice setting in later.

By Saturday SIG cold is arriving over Ireland with snow showers beginning to hit east coastal areas.

Sat night, Sunday, bitterly cold east/ne winds with snow showers hitting the east, harsh frosts, maxima near 0-2c. Snow accumulating.

Cold like to stay intense and continue in the new week.

darkman2

Don't forget next weekend it's quite likely we will have ice days with temperatures not rising above freezing in alot of places by Sunday/Monday during daylight hours. Expect to see casualties.......;)

https://www.youtube.com/watch?v=iJAezIlvC2M

roryc1

Uk looking set for some fun anyway http://www.metoffice.gov.uk/weather/uk/uk_forecast_warnings.html?day=4

Deep Easterly

Su Campu wrote: »

It remains to be seen what the weekend has in store. The latest ECMWF posted above has minimum about -8 850s, and it's a pity we can't see other parameters, like we can with the GFS. Met Éireann can, however, and therefore they feel these parameters don't add up to enough to warrant issuing snow forecasts yet.

Met eireann's online forecast (issued at 3.40am) smacks of the output from yesterdays 12z ECMWF run:

12z forecast for this coming Friday:




Met eireann's current online forecast for the end of the week:

"Thursday and Friday will continue to be cold and dry with good sunny spells but the overnight frost and fog will be slow to clear. Daytime temperatures will remain several degrees below normal, with top temperatures of around 4 to 6 degrees and sub zero night time temperatures. The winds will be light to moderate north to northwesterly bringing some showers to north and west coasts"

http://www.met.ie/forecasts/
Having said that, perhaps they have more faith in the 00z run for reasons we will never know. As other's have rightly pointed out, take any chart with a pinch of salt for this weekend until it is within 24/36hr.

mickger844posts

darkman2 wrote: »

Don't forget next weekend it's quite likely we will have ice days with temperatures not rising above freezing in alot of places by Sunday/Monday during daylight hours. Expect to see casualties.......;)

https://www.youtube.com/watch?v=iJAezIlvC2M

Classic clip from last Winter. Great to see it again

Su Campu

Weathercheck wrote: »

Nobody was really saying we'd see snow this mid-week though were they?

No, I meant that ME haven't issued snow for the weekend as they don't see it happening.....yet.

H2UMrsRobinson

mickger844posts wrote: »

Classic clip from last Winter. Great to see it again

I know - Never get tired of that clip!

maquiladora

The current Met Eireann outlook only extends as far as Friday so obviously there is no mention of what may or may not happen on Sat/Sun.

Iancar29

Quite a heavy shower here in N Dublin , wish it was a few degrees colder outside!
I looked over a the Dublin mountains and for a split second I thought the whole thing was white! ..... Then my eyes adjusted and realized it was just low cloud! Ha

nacho libre

Deep Easterly wrote: »

Met eireann's online forecast (issued at 3.40am) smacks of the output from yesterdays 12z ECMWF run:

12z forecast for this coming Friday:




Met eireann's current online forecast for the end of the week:

"Thursday and Friday will continue to be cold and dry with good sunny spells but the overnight frost and fog will be slow to clear. Daytime temperatures will remain several degrees below normal, with top temperatures of around 4 to 6 degrees and sub zero night time temperatures. The winds will be light to moderate north to northwesterly bringing some showers to north and west coasts"

http://www.met.ie/forecasts/
Having said that, perhaps they have more faith in the 00z run for reasons we will never know. As other's have rightly pointed out, take any chart with a pinch of salt for this weekend until it is within 24/36hr.

they might believe the shortwave will have a mind of its own in the end and prevent the deep cold coming in behind. it wouldn't surprise me if that happens. damn i'm beginning to sound like Gerry Murphy:p

darkman2

They (ME) are looking at the exact same charts as we are. We are not dependent on what ME says so I don't understand why people keep bringing it up. For people with internet access ME is pretty much redundant in terms of national forecasting for us on here. We have enough information to come to our own conclusions.

Deep Easterly

nacho libre wrote: »

they might believe the shortwave will have a mind of its own in the end and prevent the deep cold coming in behind. it wouldn't surprise me if that happens. damn i'm beginning to sound like Gerry Murphy:p

And so you should! for all of Gerry's unpopularity for not mentioning the S word in accordance to our whims he tends be fairly spot on when wintry showers are being forecast as to what type of showers they will be.

JanuarySnowstor

darkman2 wrote: »

They (ME) are looking at the exact same charts as we are. We are not dependent on what ME says so I don't understand why people keep bringing it up. For people with internet access ME is pretty much redundant in terms of national forecasting for us on here. We have enough information to come to our own conclusions.

Well put darkman.
Interesting to note that sheltered spots in Cork are still covered in frost & the cold spell has not arrived yet.
I would think frozen pipes time this wkd for sure!!
It does look very dry though for most even at the wkd (by most i mean those living in cork:D)

M.T. Cranium

Obviously I don't want to ramp too much in case the models start backtracking, but if the models are right within 2 deg at 850 mbs and one interval of thickness (colour separation on GFS), there would have to be some massive snow potential as that cold air streams across the 10-12 C waters of the North Sea and Irish Sea (for the North Sea that might be falling rather quickly to 7-9 C). Imagine the stability profiles with this air mass heated from below by that sea passage. This could turn into a very heavy snowfall situation if the low from Norway to France over the weekend time frame turns out any more tightly packed, and with that temperature gradient and some upper support, I would not rule this out, watch for that development on later model runs ... and this can only increase snow potential because the stronger the wind speeds, the less time the air has to modify beyond snowfall producing boundary conditions.

It would not worry me for snow potential if the M2 buoy started to show readings like 5/2 temp dp during the height of the cold outflow, since we can expect strong to extreme modification right over the water, but this will be forced out of the boundary layer by the heavy convection. When this snow arrives on Friday in the east it would likely be accompanied by some thunder in places, and just a random phase change situation right along the shore perhaps.

Backing up to this Wednesday meanwhile, it's already looking fairly promising for the showery precip to change over to snow at increasingly low elevations until possibly this elevation boundary lets in the majority of the board if not the population at large, we are already seeing marginal conditions for snow by 12z Wednesday. The slight warming from there to mid-day Thursday could be deceiving too because it's based mainly on the frontal boundary edging back towards Ireland but by then it will be off the west coast, so you might see a sort of mini-breakdown winter mixed precip event taking the time slot of this warm advection before the really cold air arrives.

There is so much model agreement, and so little by way of downgrade cycles on the approach to this period, that I feel confident that it will deliver, and the look of the pattern past the reliable time frame is one of setting up a frontal boundary NW-SE to the west and south of Ireland, I am not very convinced by the GFS and its rapid return to mild weather in FI.