Model Output Discussion - The Start Of Winter

[Jason M]

Day 15 of GFS opp

 

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0

 

Day 15 of GFS (P)

 

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=384&code=0&mode=0&runpara=1

 

Pretty good agreement at that range I'd say

[draztik]

temp anom/ days 10-15 ecm control.

 

Merry Christmas.

[snowangel32]

The good thing is that the pub run is famous for showing outrageously cold blizzards, easterlies, storms etc, which plenty more often than not, never happen.

 

I trust there's a good cold spell coming when there is absolutely none forecast in the models, especially the 18z :-)

I hope so but it will be just our luck if it has got this one correct, but tomoz is another day so still hopeful.

[Thundery wintry showers]

As BornFromTheVoid mentioned in the Central England Temperature thread, there is potential for some exceptionally warm temperatures- possibly record-breaking- for central and southern England on the 18th December, due to a broad "warm sector" moving eastwards.

https://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20141214;time=18;ext=96;file=h850t850eu;sess=3aadc7e5d4d3344ce7d99162b6daad9e;

The most significant shot at snowfall comes just after that, with a north-westerly on the 19th, but with 850hPa temperatures mostly above -6C (which I tend to use as the "snow threshold" in showery situations) we're probably looking at rain, hail and sleet showers at low levels.

https://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20141214;time=18;ext=120;file=h850t850eu;sess=3aadc7e5d4d3344ce7d99162b6daad9e;

 

I wouldn't quite rule out a bookies' white Christmas yet (in the sleet/snow falling sense) but the odds are lengthening with a mild moist west to south-westerly flow more likely than a chilly north-westerly.  I agree with the suggestions that a colder drier spell is more likely into January, but I am not seeing much evidence that there will be a significant pattern change this side of January.

[Chris K]

The good thing is that the pub run is famous for showing outrageously cold blizzards, easterlies, storms etc, which plenty more often than not, never happen.

 

I trust there's a good cold spell coming when there is absolutely none forecast in the models, especially the 18z :-) 

 

I realise it is known as the pub run....but if other models and runs are along similar lines it screams agreement...so I think the opposite

 

Still...anything after 5 days can often change dramatically, sometimes even closer than that. 

 

A case of continuing to watch and wait....hopefully not until winter 2015/16 haha!   "Patience"...as they say...

[Ali1977]

GEFS are surprisingly looking good for a decent shot of cold on Xmas day, the North defo in for a chance of snow. Heights piling into Greenland also.

In fact, they are really good. All is not lost with many showing -4c or colder uppers heading in.

Edited December 14, 2014 by Ali1977

[nick sussex]

Lots of 'likes' for this post from Nick but the reality is there is CURRENTLY little in any of the more reliable models, yep the b anomaly charts that yet suggests any marked change by Christmas, a bit less than 2 weeks away. I made the following note having looked closely at the latest NOAA 8-14 output, take it or leave it but I would be very surprised if a major pattern shift occurred before Christmas in the upper air

 

Noaa Sunday 14 December 2014 notes

6-10 and there are no marked differences from previous outputs to me; the +ve area wsw of uk is a shade nearer but the overall ridge-trough positions etc looks the same

8-14 in most aspects the same as before, the only change is the +ve area has increased from the azores +ve area, as it was a few days ago, to now extend from the area well west of Iberia to include a +90dm anomaly into ne America and sw Greenland. Remains to be seen if this is significant-currently no sign at all of the flow into the uk veering to a more n of west flow-this takes us to 28 dec!

Where did I say a marked pattern change? I simply suggested that more upstream amplification might deliver something colder around Christmas and into the New Year.

 

It was hardly in the realms of some Daily Express headline! The general correlation with troughing digging further south into the USA is some more amplification ahead of that, I also mentioned earlier today theres little chance of a proper Greenland high but some lifting out of low heights in southern Greenland which might allow a northerly.

 

It would be nice if people didn't read into posts something that wasn't there, I mentioned colder not some deep freeze with Ice Fairs on the Thames!

[SE Blizzards]

GEFS are surprisingly looking good for a decent shot of cold on Xmas day, the North defo in for a chance of snow. Heights piling into Greenland also.

In fact, they are amazing. All is not lost with many showing -6 or colder uppers heading in.

 

Yep, best set of Ens we've seen all Winter by the looks of things.

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=300

 

Lots of 'potential' there.

 

Just when you thought it was a done deal.

At least we can look forward to tomorrow now with a little interest 

Edited December 15, 2014 by SE Blizzards

[Cheshire Freeze]

Yep, best set of Ens we've seen all Winter by the looks of things.

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=300

 

Just when you thought it was a done deal.

We can look forward to tomorrow now with a little interest 

How often have we seen the NWP pick up a pattern change in the past, drop the idea, then bring it back a couple of days later?? Very often is the answer.

[Winter Cold]

Nice to hear the GEFS can bring a smile to coldies to end a tough day. Lets hope for better charts tomorrow! The ECM really was horrible and the fact that there wasnt a single post throughout the whole hour of the run said it all.

 

Ive sent this to Santa tonight, and the good news is ive been a good boy this year

 

[Banbury]

The Ens have some interesting runs

http://modeles.meteociel.fr/modeles/gens/run/gensnh-20-1-288.png?18  20

http://modeles.meteociel.fr/modeles/gens/run/gensnh-19-1-288.png?18  19

http://modeles.meteociel.fr/modeles/gens/run/gensnh-17-1-360.png?18   17

http://modeles.meteociel.fr/modeles/gens/run/gensnh-16-1-336.png?18   16

http://modeles.meteociel.fr/modeles/gens/run/gensnh-15-1-300.png?18   15

http://modeles.meteociel.fr/modeles/gens/run/gensnh-13-1-348.png?18   13

http://modeles.meteociel.fr/modeles/gens/run/gensnh-11-1-312.png?18   11

http://modeles.meteociel.fr/modeles/gens/run/gensnh-9-1-276.png?18    9

http://modeles.meteociel.fr/modeles/gens/run/gensnh-8-1-312.png?18     8

http://modeles.meteociel.fr/modeles/gens/run/gensnh-7-1-324.png?18    7

http://modeles.meteociel.fr/modeles/gens/run/gensnh-3-1-324.png?18    3

http://modeles.meteociel.fr/modeles/gens/run/gensnh-1-1-300.png?18  1

Certainly enough to keep some interest

[Abyss]

Met Office at t144. Heights building over Greenland

 

 

 

Now the GFS at the same time

 

Boxing day-Heights growing over Greenland

 

27th

 

High pressure still over Southern Europe and uppers aren't great but it certainly has a lot more potential than the previous run in my opinion. My first time posting on charts so go easy on me ha

[West is Best]

Yep the 0z GFS persists with high pressure building over France. The Azores high ridges eastwards as early as T72 on the latest run, and parks itself over continental Europe. For cold lovers this isn't a great sight.

 

By the way, I didn't think the 12z ECM was that poor. At T120 the high shows a sign of retrograding. Admittedly it then heads back east to the same position as 0z GFS but in the meantime the PV has also gone wandering again from Iceland to northern Scandinavia. Signs for hope there. I await 0z ECM with interest.

Edited December 15, 2014 by West is Best

[Iceaxecrampon]

Christmas Eve.

 

Bank.

 

 

....for Northern Britain at least.

 

Ian

[Captain Shortwave]

The window is still there for a northerly blast between Christmas and New Year

Probably looks like the best chance of giving a widespread chance of snow, mostly in the form of showers. If the downstream amplification works in our favour.

Very little worth talking about elsewhere, a little bit of mild mixed with some cooler spells.

[bluearmy]

Post Boxing Day anomolys still promise a potential wintry trough though after a couple of days, the gefs are more like 'pin the tail on the donkey' with their handling of HLB around the NH and the anomolys become weak.

ECM extended anomolys also remain positive for this timescale re cold yet the 12z suite didn't inspire confidence in a wintry period.

Oh, and bomber - sorry, no Greenland height rise on that Ukmo day 6 chart. All purples.

[IDO]

The potential shown on the GFS hi-res (and some members) for a Greenland ridge, be it only a temporary feature for the last week of December is possibly diminishing. It was never a large cluster but is now modelled to be overrun by subtle changes in the phasing and PV movement. This was never going to lead to a pattern change, it was always a variation on the current theme. The possibility of changes was from the Alaskan Ridge development at the end of the month and by the 30th there are about 60% of ensembles showing this. Again it favours the US for cold and the UK keeps average at best according to the mean:

 

 

 

It is so far out it can only be treated as a possibility but the trend is there so some confidence.

 

The next 12 days plus offers little but a continuation of the current theme. D10 charts from ECM & GEM:

 

 

 

There remains very little chance of a block setting up before January and although there will be at least two PM shots, the possible amplification of the Greenland Ridge after Christmas is less likely this morning (still a 25% cluster) due to the hi-res runs moving away from this. For example the Control now sends heights through the UK and the extreme cold travels into Continental Europe and of course the US:

 

 

The GFS P gives us a UK HP scenario (South dominant) from the 22nd to the 30th+: 

 

 

 

So again the most likely scenario is a continuation till the end of December for the zonality but possibly a N/S split towards the later stages?

 

 

 

 

[knocker]

Need keep an eye on the track of this fella.

Chart weatherbell

 

[BLAST FROM THE PAST]

Talk about stuck in a rut, that AZH will not give up the ghost and looks like being the thorn in the side for some more time.  Previous attempts to get it to move and ridge up into the Atlantic have failed and I'd suggest now that more of the same for a while yet.  Bartletts brother but not so nasty for coldies as Pm shots are and have been achievable.  Can't post charts but look at Friday into weekend....more transience as the superglue holds.

I think I'll come back after Christmas as just looking at rinse and repeat.

 

 

BFTP

[BlueHedgehog074]

Having managed to resist the evil addictive powers of Model watching for a whole 24 hours or so, have noticed some of the models are continuing to be keen to build height rises over to our West and North-West in quite deep FI. In fact, models like the GFS 00Z run seem to have improved on this the last time I looked at it. With some of these solutions being in FI, that usual caution will be needed. The other problem I can see about this is that the Azores High seems eager to become the cold and snow fans' enemy by taking a nap over to our South/South-East. As such, despite some of the height rises shown towards our West or North-West, the Sourh/South-Eastern UK high prevents Atlantic Lows from dropping down to our East to provide the cold and snow fans with a chilly flow from the North or East. An example from the GFS 00Z at 240 hours - height rises towards our West, but with the High Pressure over Europe creating a forcefield for Atlantic Lows to track Eastwards/South-Eastwards...

I know it's not really worth getting to hung up on details as it will likely to keep chopping and changing at that time-frame, but there does appear to be some kind of trend to builds heights to our South-East and something that could prove to impede cold weather development. It would be fair to say, though, that the GFS 00Z run does eventually offer the cold and snow fans' a Northerly treat in FI as we see enough amplification to the pattern to our West for Low Pressure to push Eastwards against the South-Eastern UK block. There is also that idea that enough amplification to our West could allow Lows to the West/North-West to drop down far enough South to our East to squeeze the European High back to our West and create stronger blocking in the Atlantic.

For this week, though, the models show the weather being dominated by Atlantic Lows to our North and the flow generally being between the South-West and North-West. Some spells of rain and showers are likely at times, especially to the North-West. Generally fairly mild at first (though cooler the further North you go) with some quite cloudy periods at times, but should gradually become cooler for most later on in the week as we see a cool Polar Maritime shot from the North-West - a chance of some rain, sleet and hail showers for North-Western areas, too.

[Man With Beard]

I don't quite see it like that IDO. It is true that the HLB signal from GFS is a bit erratic but you'd expect that at T 300+. But what I factor into my thinking is that it's not in the model's nature to come up with HLB in the areas it has suggested. That makes me think there is a stronger possibility of it actually happening. And the west based -nao has come up too many times now for me to think something similar won't be showing by, say, 28th December. As CS demonstrated, the end mean at T300 has a kink of heights towards Greenland, pretty unusual at that timeframe. Of course, it doesn't guarantee anything snow wise for the UK, but it would be close. There would also be a good chance that a west based -nao would drift towards us over the course of a few days, giving us a white new year. That's my preferred "guess" actually - winteryness saved for Scotland over Christmas/Boxing Day, then a few milder wet days, followed by a short cold snowy snap around New Year for two or three days.

[TEITS]

Whilst it seems some have given up on a pattern change, I remain confident this will occur shortly after Xmas.

 

http://www.wetterzentrale.de/pics/Rtavn2761.gif

 

Even a white xmas for some cannot be ruled out yet although I believe the real cold will occur shortly after xmas.

 

http://max.nwstatic.co.uk/ensimages/ens.20141215/00/t850Aberdeenshire.png

[Buxton Codge]

All looks very similar to January 2014 as we head into 2015 with the Alaskan ridge providing the North Eastern States with a harsh wintry period which will fire up the jet across the Atlantic.

I still expect some wintry weather over the Christmas period but this will be fairly short lived based on todays model output

[Penrith Snow]

ECM a lot better this morning, we still get the pre Christmas mild spell but the displaced AH is a lot further south by Christmas Day but cold north westerlies across the UK.

The high being over the Med rather than France allows the PM shots to continue so no real change from the current set up but at least the Christmas Bartlett has gone.

Andy

[IDO]

ECM a lot better this morning, we still get the pre Christmas mild spell but the displaced AH is a lot further south by Christmas Day but cold north westerlies across the UK.

The high being over the Med rather than France allows the PM shots to continue so no real change from the current set up but at least the Christmas Bartlett has gone.

Andy

 

Yes  better but knowing the ECM, likely to change again by the 12z. Bearing in mind the Christmas Day mean suggests a different phase of PM/TM, I would say still in the balance re Christmas:

 

 

The GEFS highlight this uncertainty, highs from 2.5c to 12c!

 

A Merry Christmas from gem: