Wintry spell forecasting discussion - 23/11/2010 onwards

COLDEST ENDING TO NOVEMBER SINCE..


Major cold and some snow is on the way the next week to 10 days across northwestern Europe and London is liable to see the heaviest pre-Dec. 1 snow in at least 19 years (that is all I went back last night). The winter season of 2005-2006 came out of the box fast too (another mega hurricane number year) with the number to beat the last five days of the month in London town at -6.7. So we have to shoot for that and accumulating snow, and I think we are going to get it.

The cold will last through the first week to 10 days of the month but will back off after that. This is not the winter pattern yet. What is going to happen for the heart of winter is the block, now over Greenland and Iceland, will reform over Scandinavia and into the northern part of Great Britain. This will allow the mean trough to form underneath for the heart of winter, hence the threat of the major winter in the coldest part of the year farther south. It's like what will happen in the eastern U.S. the next 3-4 weeks, a rip-roaring start to winter there, then it will reverse. Well the rip-roaring start in Europe this year is not where the heart of winter will be cold. I understand all of you that disagree with me are upset, but look at it this way. If I am wrong, then you should be happy about it; if I am right, no use worrying about it anyway.
Enjoy the weather now in the area having the early winter shot

http://www.accuweather.com/ukie/bastardi-europe-blog.asp

maquiladora wrote: »

Weve probably got another 10 days or so left before this cold spell might start to breakdown

ECM's ensemble mean run keeps it cool right up to 240hrs as well (850 temps):




although hints that a breakdown from the NW may happen thereafter.

Now thats more like it for the east if it holds or improves. Hopefully any heavy showers can extend to most of us further inland.

Jumping in snow that hasnt been touched :rolleyes:

An irish winter will be remembered as a classic if it includes 2-3 significant snow events. This same winter may be classified as having recorded slightly above average temps. However, I would take it over the deep freeze that Joe B is predicting for southern and Eastern Europe.

Cutting all the nonsense of who is right and is Joe on the money, the signs are pretty clear and have been since early September that Ireland is going to see some northerly and easterly blocking systems battle with the Atlantic which, despite a 2 week period of dominance over our weather at the beginning of this month, is not as active as in recent years.

It is as a clear as day to me and others who read the outputs day after day that the Atlantic very well may break down the current blocking scenario but it won't introduce much more than average temps for the time of year. Even then I am confident that blocking highs to our north and northeast will engage the milder Atlantic influence over our weather, hence creating the 'classic' significant snowfall scenario for Ireland i.e. Ireland being a battleground between cold and warmer systems.

Joe also forgets about the microclimate that exists in Ireland and to a lesser extent in Britain. We are both islands at the butt end of the gulf stream. He has been right in the past but he has equally called it wrong for the British Isles on other occasions. Would like to see his rationale behind his outlook explained a little better. I don't see where he is getting the notion that blocking highs are going to drift further east when all the evidence suggests the opposite.

whether he is right or wrong, only time will tell. My money is on this cold spell breaking down by december 10th, followed by a period of 'normal' atlantic influenced weather up until Christmas or shortly after. We will then return to a similar set up to what we are experiencing now. this outlook is based on how the weather has been behaving for the past 2 months.

ps...i don't know if we will have a country for snow to fall on come Christmas. Vincent Browne show tonight was one of the most sobering pieces of tv i have ever seen. This great country is well and truly in trouble

The real game changer for this weekend is a low pressure system just starting to form to the south of Svalbard this evening, as shown in the Norwegian Met's 1800UTC analysis below. There is a nearby northerly jet of above 100kts, as seen in the 1800 Bjørnjøya sounding, which is just east of the jet axis.

1800 Analysis



This jet will serve to strengthen the susrface low as it moves southwards towards northwestern Norway by 1200UTC Wednesday.




One thing I note from the recent midnight observations is that the pressure at Hornsund (1025.7hPa), on the southern tip of Svalbard, is already a couple of hPa lower than the 12Z ECMWF had forecast for this time (~1028hPa). This could be a signal that the model does not have a handle on the evolution of the low up to now, and so future runs could post a lower low than previously, as per the 18Z Icelandic HiRLAM, which has the low at around 1003hPa by midnight tomorrow, where the ECMWF had it at 1005.

00Z tonight ECMWF chart (12 Run)


The 18Z GFS is also similarly out on the low tonight, so we could see both models showing slight changes in the depth and track of this low over the next couple of days.

00Z Pressure observations

pistolpetes11 wrote: »

When you say game changer , do you look at this as upgrade or downgrade ?

Maybe game changer was a bad choice of words.....it's always been on the cards (or charts!), so it's nothing new, but I meant that how it behaves will have a direct bearing on how our weather behaves over the weekend, so a shift either way will have a bearing on the exact properties and track of the airmass.

A comparison from last year...

Note.. SST's 4 degrees warmer and we are 3 weeks before the shortest day of the year instead of 2 weeks after it. Obviously the snowfall will not be as widespread

This is what came of the 1st chart






and for this weekend....