Discussion on Winter LRFs (9/10/2006)

darkman2

Hello!!!!!!!:D

I know were all concentrating on the storm potential this time off year but we cant put it off any longer!!

Well its that time of year again when attention gradually turns to signals for the upcoming Winter.:D

First off Im gonna nail my colours to the mast and say that this Winter IMO will be similar to last Winter. Average - Slightly below for the CET. My confidence generally comes from current SST's which remain below average across much of the North Atlantic and above average in the North Sea. So we would expect more cyclogenisis over the North Sea given the extent of this anomally. There is a quite warm anomally however off the Eastern Seaboard of the US and east of Newfoundland (as there has been all year) and this is not really what we want to see (it is quite a warm pool and its gradually moving East). However as long as the anomally remains cool North Atlantic and warmer over the North Sea the trend is condusive to blocking and this tends to lead to below average temperatures (as happened last Winter) and generally the blocking theme has continued leading to generally more periods of continental flow though this is probrably not too noticable to most. Its good to see for those of us who want a below average Winter. It must also be said that snow is actually arguably less likely in a below avergae Winter for us.

http://weather.unisys.com/surface/sst_anom.gif

Anyhow more on that soon. Getting down to buisness and the first LRF has been issued:



As you can see quite above average for the planet really. I get the feeling it might be a tad biased toward the GW brigade however. As with all forcasts you get this year from NCEP to the UKMO they are all experimental.

Interestingly the UKMO has also given a provisional hint of possibly a warmer Winter. We shall see. More soon:cool: http://www.metoffice.com/corporate/pressoffice/2006/pr20060710.html

Any thoughts??

Snowbie

I personally think DM that according to the temp annomolly concerning the waters temps NW of Ireland are likely to be higher are perfect for the formation of polar lows,giving us the chance of snowfall throughout the country.Now i reckon that it is this for our real chance of the white stuff from a presistant Greenland or artic blast that the cold will interact with the warmer waters will generate PL.Albeit conditions will be tempered if an unusally warmer than avg continent will affect us.
Havin said that i have not seen much in the way of an Easterly blast that has really plummet the temps here during the last winter and then that was a colder than avg continent.I would not hold my breath on a easterly that was so dominant in 1982 to happen again with low extreme values and lots of snow.
So its to the NW or N we shall look for PL to form to give us a chance of a better snowfall to come.Very early to tell.

darkman2

Snowbie wrote:

I personally think DM that according to the temp annomolly concerning the waters temps NW of Ireland are likely to be higher are perfect for the formation of polar lows,giving us the chance of snowfall throughout the country.Now i reckon that it is this for our real chance of the white stuff from a presistant Greenland or artic blast that the cold will interact with the warmer waters will generate PL.Albeit conditions will be tempered if an unusally warmer than avg continent will affect us.
Havin said that i have not seen much in the way of an Easterly blast that has really plummet the temps here during the last winter and then that was a colder than avg continent.I would not hold my breath on a easterly that was so dominant in 1982 to happen again with low extreme values and lots of snow.
So its to the NW or N we shall look for PL to form to give us a chance of a better snowfall to come.Very early to tell.

Good to get an opinion there Snowbie. A polar Low is of course very very unusual in Ireland. The definition of which is a deep and compact area of LP without a mild sector (or at least what we would percieve to be mild) therefore rain is hard to come by. Its mostly snow. It would be great to see one again but Ive only seen one in my lifetime in this country so very very unusual indeed.

It must be remembered that last Winter a blocking pattern was obvious and this could be a very good omen for this winter. Watch out for those easterlies. Ive a good feeling about this season:)

BTW Snowbie I propose a sticky for this thread. Cheers...:D

lucernarian

Any polar lows like 2001 (not sure if that was a proper definition PL) would be very welcome:eek:

Snowbie

Yes that was a polar low in march 1st 2001.Snowed all day iirc.As the eastern side of the country got a covering the NW was hammered.

Although PL do happen in this country they are not frequent but do release some precip on us overall when they occur.

1982 was the coldest spell i remember with biting easterly for over a week from Jan 8th onwards,and a lot of snow to the east.

1987 A PL again just like the one in 2001 but this released more snow from it on the east but the North was worse affected.I measured 4.5" flat and drifts of over 1 foot.

Then 1992 had three snow events in one month span.
1.Was January when it turned out to be a blizzard.First one in a long time.
Being raining all day with temp of 4c,then the cold air dug under the rain belt with wind gusting and had rain readidly turning into snow.Covered in minutes.
2.Feb 7th brought heavy snow showers in on a stiff NE wind, which a few of them was thunder snow too,first i had ever seen.A few inches fell in constant and merging showers.
3.Feb 9th,just two days later,no body saw this coming including the met service.Dead calm out and bitter.Snow started to fall which then came down heavier with massive flakes.About 6 inches.This was no where forecast from anyone and was beyond me.I reckon that a PL formed off the east coast and dumped snow over Dublin Meath and Kildare.Funny thing there was never an explanation from the met to what happened as the earlier forecast was dry and cold.And after the event the forecast was for heavy snow for the east.It was practically over then when that was issued.I say a shallow PL formed over the Irish sea.
MT Pinatouba in signapore erupted in 1991 and changed the climate of the globe for two years decreasing temps which might connect to why we had three snow events in a month???????

Then all the way to 2001 no significant snow untill then.A lot of easterlies between and after but i dont see the coldness that they really had back in the 80s.

lucernarian

Snowbie wrote:

1987 A PL again just like the one in 2001 but this released more snow from it on the east but the North was worse affected.I measured 4.5" flat and drifts of over 1 foot.

The snow which hit here on 27th February 2001 had about 5/6 inches level and drifts found almost a week later of 4-5 feet:eek: Mind you, the FAX chart for the day was so perfect for where I live, I doubt I will see a PL as potent hitting this location ever again in my life.

As for LRFs, is there much of a science to them? They can turn out completely different. Can you say that successful predictions are anything more than luck or at least "2 wrongs making a right" e.g. double mistakes?

Snowbie

There was a lot of energy in that PL,most of the moisture content would usually be gone by the time it reached the southern half of the country and depending on the track of the low.
Now as for LRFs,there comes a time to stand back and consider the accuracy with them.They are only a prediction,last years was correct,the one released in November.It was spot on.So maybe a two to three month prediction would be far more accurate than a four to five month.
January has in the last few years has been a lot drier and milder.
Febuary usually our coldest month.
March"of many weathers" has been colder than recent years(10 or so years ago) and a lot more snowier.
Is there a trend happening here? Just going by past years.

darkman2

First 510DAM line over Greenland. This is far earlier then usual and is good to see:D

http://www.wetterzentrale.de/pics/Rtavn063.png

nacho libre

thanks for the good tidings Darkman:D

A polar low would be most welcome this year. I long for a winter like they had in England in 1962/63. I know with our location this is extremely unlikely to occur but one can dream.

Snowbie

nacho libre wrote:

thanks for the good tidings Darkman:D

A polar low would be most welcome this year. I long for a winter like they had in England in 1962/63. I know with our location this is extremely unlikely to occur but one can dream.

A winter they had in England this year would do me tbh.

darkman2

Just to say the UK Met Office Winter forcast will be out in full on the 21st of September:)

mike65

1962/63 temps with leccy and gas prices through the roof?. Some of us are not weather fantasists and have bills to pay.

Nothing worse than last winter please.

Mike.

darkman2

mike65 wrote:

1962/63 temps with leccy and gas prices through the roof?. Some of us are not weather fantasists and have bills to pay.

Nothing worse than last winter please.

Mike.

You think last winter was a 'real' winter?? LOL!!:D

If mike was around in the 80's which I know he was, he'll know what real winters were.
Being able to walk on the UCD lake was common.Not knowing exactly where it was as the snow had drifted over it was also common.

mike65

I remember 1982, snow for a week etc I also know I much prefer it not to be that cold. The (town) gas bill that winter was vast.

Mike.

Snowbie

Be honest with you all,you dont have to use the gas for the price to be through the roof.So if it where warm or cold its still high.:(

Strasser

UK Met office have just issued their latest winter forecast at
http://www.meto.gov.uk/corporate/pressoffice/2006/pr20060921.html

BigCon

"Forecast for Winter 2006/7
Temperature
Over much of the European region, the situation is now finely balanced with approximately even chance that the winter will be colder or warmer than average.
For the UK, temperatures near the 1971-2000 average are slightly favoured for the winter season as a whole. However, later in the winter season, there is a signal for lower temperatures (relative to average) and an increase in the frequency of cold snaps.
Note that even an average winter is likely to include some notable cold snaps and snowfalls. "

Good job WC's not around here, he'd be wetting himself

Snowbie

What site was that abstract taken from?

BigCon

UK Met office

Snowbie

Cheers.

darkman2

Well, its in line (kind of) with my forcast. We need more time really. This is still very early for Winter forcasts admittedly. Though it is very encouraging given current SST's.:)

darkman2

Ok time to update this thread. Currently things are looking very good indeed. I would draw your attention to the cold pool to our north which continues to build quite nicely. Already in FI indications are that the first credible northerly is on the horizon. 850s currently at -25C over Greenland. Thats a real improvement on this time last year. Also some indications from Germany on what we may expect. I will post charts etc soon. Looking good.:)

darkman2

darkman2 wrote:

Ok time to update this thread. Currently things are looking very good indeed. I would draw your attention to the cold pool to our north which continues to build quite nicely. Already in FI indications are that the first credible northerly is on the horizon. 850s currently at -25C over Greenland. Thats a real improvement on this time last year. Also some indications from Germany on what we may expect. I will post charts etc soon. Looking good.:)

I will post charts soon but I have to say there are some quite remarkable charts appearing in FI on all models. The concensus being that an East or Northeasterly is on the way. Its still early and we wont see snow by any means but if this trend continues then we could be in for a remarkable season. October atm looks set to end on a chilly note:)

Snowbie

Making this a sticky
In light of growing confidence from ECM,SST and GFS,Statistics and sunspot minimum have put this Winter as been interesting.Similar or slightly below temps from last Winter.

We shall see.As it is still early days.
Please post charts or links here.

This is a discussion on winter LRFs and not predictions of snow events.

Snowbie

DM you can relate to this too
This is a good abstract refereing to a near changing trend to cooler weather.

October has brought some interesting weather so far from the likes of heavy rain and gales to some chilly nights but also some continued mild daytime temperatures and the coming week won't be any different. Plenty of varied weather will be accompanied by generally above average temperatures. After a very mild September and a generally mild start to October, will temperatures ever become average or below average again?

What we are watching is the development of high pressure towards the end of the week and beyond. There is a growing signal for some extensive high pressure areas to dominate across parts of the Northern Hemisphere into the middle part of the month, especially over Greenland and surrounding areas. Depending on the development and track of low pressure systems there is currently a risk of some significantly cooler weather, if not cold weather spreading across the UK from the North or Northeast beyond mid-month, this would certainly create a very different feel to the weather and finally introduce some average or below average temperatures.

More on this in the coming days and weeks

There is talk of blocking HP systems north of scotland/scandanavia regions this coming Winter.The above mentioned has been modeled a month ago and still a couple of weeks away looks probable now but with still room for change though.Time will tell.

darkman2

Snowbie wrote:

DM you can relate to this too
This is a good abstract refereing to a near changing trend to cooler weather.



There is talk of blocking HP systems north of scotland/scandanavia regions this coming Winter.The above mentioned has been modeled a month ago and still a couple of weeks away looks probable now but with still room for change though.Time will tell.

Yes Snowbie, yes absolutely. The more high latitude blocking the better. ATM things look condusive to high latitude blocking. I would caution though that we have seen this before and it has not worked out. This season however does seem onimous in the sense that we had this last season (winter) and with that being a below average CET we must be confident for this season. Things have changed since the run of mild winters. We are in transition to colder winters and this year may be the year we have been waiting patiently for!!!! fingers crossed:)

Snowbie

True Dm,its wheater the weak El Nino will affect this is uncertain.But it could get interesting if weather systems from the Atlantic meet the cold air being drawn in from a NE to East direction if the block subsides a bit alowing fronts to move across and meet the cold air,could make for interesting discussions then.IE:frontal snow.

As this is the case in many years leading only to cold wet and miserable conditions depending on a sustained cold pool from the east might be more condusive for this to happen. EG:Jan 8th 1982. It happened then.

So our first cold snap was 25th Nov 2005 last year and looks like we will get our first chilly peroid a month earlier this year in late October.Will the trend continue and our above mentioned materialises into more of an NE to E block or will we see the influence of the Atlantic more with an El Nino winning.???

darkman2

Snowbie wrote:

True Dm,its wheater the weak El Nino will affect this is uncertain.But it could get interesting if weather systems from the Atlantic meet the cold air being drawn in from a NE to East direction if the block subsides a bit alowing fronts to move across and meet the cold air,could make for interesting discussions then.IE:frontal snow.

As this is the case in many years leading only to cold wet and miserable conditions depending on a sustained cold pool from the east might be more condusive for this to happen. EG:Jan 8th 1982. It happened then.

So our first cold snap was 25th Nov 2005 last year and looks like we will get our first chilly peroid a month earlier this year in late October.Will the trend continue and our above mentioned materialises into more of an NE to E block or will we see the influence of the Atlantic more with an El Nino winning.???

An example of what may happen shortly:

http://www.wetterzentrale.de/pics/Rgem2281.gif



Monthly Outlook from UKMO:

Valid for Sat 14th Oct to Mon 23rd Oct 2006
With high pressure expected to be established to the north and east of the UK, plenty of dry weather can be expected during this forecast period. Easterly winds will bring variable cloud and some sunshine by day, but thicker patches of cloud are likely to bring some patchy rain or drizzle in places, especailly in the south and west with any risk of heavier rain confined to the far southwest at first, However, the risk of heavier rain does extend further northwards and eastwards across central and southern England along with Wales into next week. Temperatures should remain close to the seasonal average well into the period. Later, there is a chance that colder conditions may spread southwestwards across the UK with some showers developing in the north and east, these perhaps wintry over hills. Clearing skies at night will allow temperatures to fall smartly with a steadily increasing risk of frost, particularly for more sheltered central and western areas.

Snowbie

The NAO for this Winter is out:Mild and Wet.

http://www.bbc.co.uk/weather/ukweather/monthly_outlook.shtml

Maybe the EL Nino will affect us this coming winter?

darkman2

Snowbie wrote:

The NAO for this Winter is out:Mild and Wet.

http://www.bbc.co.uk/weather/ukweather/monthly_outlook.shtml

Maybe the EL Nino will affect us this coming winter?

Hi Snowbie,

The NAO is, of course, a variable and is due to go negative sometime during the second half of November. What we will be looking for now is a strenghtening of the GH and the emergance of the Siberian High. The GH is going to deplete over the next few days and be replaced by low pressure. This is not good, however, it's far better that it happens now then say in January. The Jet Stream is also going to gather pace across the Pacific and Atlantic Oceans in the absence of blocking. This will mean typcally 'zonal' weather for the next while but the jet will amplify eventually and split and that will see the GH re-emerge with hopefully additional blocking in the right places for us at high latitudes.


The UKMO will update it's Winter forcast on Wednesday. Should make for interesting reading:)