Winter Model Discussion - The Hunt For Cold -12z 14/12/12

[IDO]

The way its going southern areas are going to be very close to average December fare in 2012, especially if we get temps like this at 3am:

http://cdn.nwstatic....9/ukmaxtemp.png

The week before Christmas will be very mild with +10c uppers frequenting the south from a long fetch SW flow.

Edited December 15, 2012 by i'm dreaming of...

[Matty M]

At least it will be mild!

[Dampdorset82]

Well, if this is anything to go by, it's time to put away the sledges and breakout out the BBQs!

http://nwstatic.co.u...acf167a5a2b71e;

The cold is being pushed further away in this run. I think it would be fair to assume there would need to be a major change in synoptics at such short range for cold (snowy) conditions this year which is highly unlikely but not enirely impossible. Still im interested to see how mild we could get from this showing.

[blizzard81]

This is all getting very bizarre!

I just don't see how you get to an easterly with the jet tilted sw/ne and pressure rises over Iberia.

The upstream pattern amplifies at completely the wrong moment, this needs to happen well before the next low exits the USA and phases with the one near the UK.

In terms of those transient snow chances mentioned by Ian F this would suggest the Russian block extends sufficiently west to help carve out a se surface flow off the continent.

And some energy being diverted se near the UK. Its a small straw to clutch onto but really we'd need to see some big changes in the earlier timeframes.

Absolutely. I'm not Meto bashing here but I again get that recurring feeling of the Meto always being 24 hours behind everyone else - behind most

people on this forum anyway! If this was yesterday morning, I would understand Meto's analysis (kindly given to us by Fergie which is much appreciated) However, things have really taken a turn for the worse for coldies with the overnight operationals - and now backed up by the 6z.

[Matty M]

Ironically there are 4 or 5 decent ECM EPS stamps at 168hrs..

The 6z GFS is nothing less than horror on a png. Blow torch type stuff

[Cal]

This is all getting very bizarre!

I just don't see how you get to an easterly with the jet tilted sw/ne and pressure rises over Iberia.

The upstream pattern amplifies at completely the wrong moment, this needs to happen well before the next low exits the USA and phases with the one near the UK.

In terms of those transient snow chances mentioned by Ian F this would suggest the Russian block extends sufficiently west to help carve out a se surface flow off the continent.

And some energy being diverted se near the UK. Its a small straw to clutch onto but really we'd need to see some big changes in the earlier timeframes.

Tis a bit bizzare with the comments from M Hugo n Ian F re -easterly potential although Ian F has stressed it is a minority possible outcome, with charts consistently showing on the GFS runs (shown below) something of a broad s/westerly airflow in 5-7 days time.

http://modeles.meteo...h-0-168.png?6?6

Would have to be a big turnaround from the GFS to start showing the slider & easterly options?

[nick sussex]

I think it probably comes down to this point in the ECM:

The model tries to take some energy se but fails in the next frame, i'd say that this is last chance saloon time, if you don't get energy heading se and splitting the trough then IMO thats game over.

Because after this with the energy going ne the Azores high ridges ne and once that happens its really a long road back to cold.

[The PIT]

Funny isn't it not long ago people were taking the deep freeze in deep FI as fact and now we've got a delayed Indian summer in deep FI it's causing panic. Although UK's default is mild and wet so the chances of it coming off are slightly higher than the beast from the east it's just as likely to modified downwards. The trend though as it has been for a while for a slow steady warm up. So wet and windy at times and getting milder.

[Jason M]

The trend for height rises over Spain and France continues apace this morning at least on the opps.

If this carries on for much longer the easterly options amongst the ensembles will really start to fall away. Whatever happens it looks like either a blowtorch or winter wonderland Christmas. It's not going to be boring over the next few days.

Rather than looking east we need to look to our south as its what happens here that's going to determine the end result in our part of the world. The trend has been clear though recently, which unfortunately is for ever stronger signal for high pressure just where we don't want it.

Noticed we have an uncle Barty posting. Will he be staying for Christmas and new year though?

Jason

Jason

[blizzard81]

I think it probably comes down to this point in the ECM:

The model tries to take some energy se but fails in the next frame, i'd say that this is last chance saloon time, if you don't get energy heading se and splitting the trough then IMO thats game over.

Because after this with the energy going ne the Azores high ridges ne and once that happens its really a long road back to cold.

Yes Nick, the difference between the ECM operational and control of this morning when compared to yesterdays ECM runs is that yesterday

they were keen to send the energy south east into Europe but today they are having none of it and the ECM has clearly moved towards GFS.

We are also 24 hours nearer to the eventual outcome so we are running out of time for the ECM to revert back to what it was showing yesterday.

[Weathizard]

I think the 12z's will put the final nail in the cold coffin, would be somewhat ironic though to see the 6z ENS produce the goods, I've seen this before, blow torch OP = betters ensembles, freezing OP = rubbish ens.

We'll see anyway, knowing the models recently we'll probably have yet another twist today.

[Snowmad79]

Blizzards on Xmas eve anyone ? You have to laugh

[blizzard81]

I think the 12z's will put the final nail in the cold coffin, would be somewhat ironic though to see the 6z ENS produce the goods, I've seen this before, blow torch OP = betters ensembles, freezing OP = rubbish ens.

We'll see anyway, knowing the models recently we'll probably have yet another twist today.

Yes, sometimes you get the feeling that the models are toying with us and leading us on a constant merry go round!!

[Matty M]

well fi looks interesting with a pv split!

[Frosty.]

WOW the Gfs 06z ignites the BLOWTORCH in FI with a spell of very mild tropical maritime air with temps around 13c, very similar to last christmas when some areas hit 14-15c on the big day, the good news is the 6z warm spell is timed to be just before xmas and xmas week itself could see a return to colder weather with snow risk in the north at least and overnight frosts, there is quite a contrast developing with a very mild spell pre christmas and a potential cold spell nearer the new year, lots to keep an eye on and a very interesting FI again.

[If Wishes made Weather]

I've been watching for trends over the past few days in the latter (low res) GFS slides from each run. As far as I can see there are three trends, or repeated elements that appear. Which will either make you laugh or cry:

- the 30hPa temps warm over the gulags somewhere giving a mysterious yin and yang pattern;

- the jet seems to power down generally (but the patterns are all over the place;

- and no matter which pattern of broken vortex ensues, the UK is without fail the mildest place for its latitude on the chart.

[Cal]

Clearly some differences between the GFS & ECM in the medium term.

GFSECM

[fergieweather]

Tis a bit bizzare with the comments from M Hugo n Ian F re -easterly potential although Ian F has stressed it is a minority possible outcome, with charts consistently showing on the GFS runs (shown below) something of a broad s/westerly airflow in 5-7 days time.

http://modeles.meteo...h-0-168.png?6?6

Would have to be a big turnaround from the GFS to start showing the slider & easterly options?

Bear in mind the analyses prepared by UKMO at that range take no notice of GFS for reasons previously outlined. The 00z suite analysis due any minute now from Ops Centre. I'll advise if there's any key change of thinking.

[Weathizard]

In the past what model/models are best at predicting the movement of the Vortex, I think the models are really finding it difficult with this at the moment.

[nick sussex]

In terms of the upstream pattern at least it doesn't look like remaining flat in the medium term, whether this upstream can feed down in time to save Xmas we'll have to see.

The problems we have really are where the troughing might be sitting when this amplified wave works its way down, but anyway these are the comments from NOAA this morning in relation to that:

HPC OVERNIGHT MEDIUM RANGE GUIDANCE HAS BEEN PRIMARILY DERIVED

TONIGHT FROM A 50-50 BLEND OF GENERALLY COMPATABLE YESTERDAYS 12

UTC GEFS/ECMWF ENSEMBLE MEANS. THIS SOLUTION MAINTAINS GOOD

CONTINUITY WITH RECENT HPC GUIDANCE. THE GEFS/ECMWF ENSEMBLE

MEANS BY NATURE MITIGATE TO SOME DEGREE LESS PREDICTABLE EMBEDDED

SYSTEM SPECIFICS/INTERACTION VARIANCE AND BECOMES INCREASINGLY

WITH TIME ON THE MORE AMPLIFIED SIDE OF THE FULL ENVELOPE OF MODEL

AND ENSEMBLE SOLUTIONS NEXT WEEK...WITH THE ECMWF ENSEMBLES MORE

AMPLIFIED THROUGH MIDWEEK AND THE GEFS ENSEMBLES LEADING TO MORE

AMPLIFIED FLOW FROM THE ERN PACIFIC INTO THE W-CENTRAL US LATER

WEEK INTO NEXT WEEKEND. THAT TYPE OF SOLUTION HAS BEEN CHAMPIONED

AND SEEMS REASONABLE CONSIDERING WATER VAPOR IMAGERY WAY UPSTREAM

OUT THROUGH THE W-CENTRAL RN PACIFIC STILL SHOWS QUITE A BIT OF

ENERGY FEEDING AND QUICKLY LEADING TO AMPLIFYING DOWNSTREAM FLOW

IN A MANNER CONSISTENT WITH A ROSSBY WAVE PACKET. WHILE FLOW

AMPLIFICATION IS EXPECTED IN THIS SCENARIO...FORECAST SPREAD WHILE

DECREASED FROM YESTERDAY REMAINS SUFFICIENT TO SUGGESTS SLIGHTLY

GREATER THAN NORMAL UNCERTAINTY. A QUICK PEEK AT THE LATEST 00

UTC ECMWF NOW CERTAINLY SHOWS THE POTENTIAL FOR EVEN HIGHER

AMPLITUDE DEVELOPMENT IN THIS FLOW AMID LINGERING UNCERTAINTY.

[blizzard81]

Bear in mind the analyses prepared by UKMO at that range take no notice of GFS for reasons previously outlined. The 00z suite analysis due any minute now from Ops Centre. I'll advise if there's any key change of thinking.

That explains my query earlier - I thought the analysis you posted earlier was based on the 00z suite.

[Cal]

Bear in mind the analyses prepared by UKMO at that range take no notice of GFS for reasons previously outlined. The 00z suite analysis due any minute now from Ops Centre. I'll advise if there's any key change of thinking.

Many thanks for the continued updates Ian, nice to have a bit of inside info from the Met O!

[snowmadchrisuk]

Blizzards on Xmas eve anyone ? You have to laugh

LOL , Love it how th uppers go from +10 to -10 in 12 hours haha .... The charts are bananas at the minute,,,,

[andy_leics22]

I haven't posted on here for a few weeks, been checking the model runs every few days and at the moment, they are absolutely hideous for cold and snow lovers! I hope january and february show signs of turning a lot colder. the ensembles make for bad viewing at the moment!

[mountain shadow]

Subtle signs continue of a brief northerly around Christmas Day again. One to watch.