Model Output Discussion: 12Z (22/11/12) And On...

[Liam J]

Breath taking charts, I can't remember ever seeing anything quite like it! Shame the real cold air never really makes it over our shores (on this run).... *picks jaw up off the floor* Is that what you call northern blocking?

[Cheshire Freeze]

Just out of curiosity, has anyone seen a vortex weaker than this in December?

[AWD]

I think I must be the only one that doesn't mind missing out on the cold for the time being and waiting until mid December for true cold potential.

It's too early in the season (referring to my specific location) for snowy/bitterly cold weather. 2010 being the exception.

Anyhow, a cool down is on the cards. Looks like temperatures will slowly fall away next week to below average values by the end of the week;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121122/18/165/ukmaxtemp.png

But remaining unsettled as a trough stays close to the UK;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121122/18/168/h500slp.png

However, my main focus point for the time being are events over the weekend. The SW has seen copious rainfall of late, with widespread flooding. We have a troublesome low coming up from the south this weekend;

http://www.wetterzentrale.de/pics/brack1a.gif

Which I can see become an increasingly concerning issue for the SW. Strong winds & heavy rain again forecast for places that don't need it;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121122/18/51/ukprec.png

All associated with a strong jet streak over the UK:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121122/18/24/hgt300.png

With yet another low shown by the 18z to affect the south early next week;

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121122/18/96/airpressure.png

So a lot going on in the short term, especially for the south. More rain coming, large amounts possible too resulting in further flooding.

Then turning colder as the week progresses, with northern blocking being shown. I can think of far more worse places to be if cold weather is what you want, than the charts we currently see.

Some realistic, early season cold weather being forecast, but admittedly, with all the weather currently going on, I haven't looked to much beyond next week, so I'll leave you all to decide how good/bad/mild/cold it's going to be.

Enjoy folks!

Edited November 22, 2012 by AWD

[EML Network]

I think the GFS will have a headache after this run, what a complex set up this is.

I think looking beyond 5 days is going to test even the most experienced forecaster, good luck figuring it out, because I can't.

Let's get to the 28th and see where we go, the 28th has always been the day where the cold starts in earnest, then it's a matter of how long it'll last, how cold it'll get and who might get lucky

[ukpaul]

And for those looking at the strat (10hPa).

Edited November 22, 2012 by ukpaul

[Cloud 10]

The gfs18z operational at day 10 is a good match for the naefs for the same time-scale,so looks

more plausible than the ecm.

18z.. naefs..

[Continental Climate]

http://www.wetterzentrale.de/pics/Rtavn3001.png!! The whole of FI is basically reverse zonality, however amusingly those blue 850's never reach us throughout

[cold snap]

It's just get colder and colder classic gfs run

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=336&mode=0&carte=1

Heavy snow coming into the south east at 336 lol

[bobbydog]

Its only the 18z but the link up between the Atlantic High and the emerging Arctic High is looking very tenuous at T144 as low pressure is further NE and this is the threatening the block. We must have that link up IMO.

yup, winter's over........ or not??

72hrs.....

177hrs....

???

[MKN]

From todays runs its quite clear that nothing is clear. Simple as that imo wait for some consistancy between runs and between models. The only view that can be considered likely is as per the BBC forecast on the 8th of this month that higher than average pressure to the north and lower than average to the south. How that will effect us is up in he air imo.

[Panayiotis]

Happy with this run shows Northern blocking from +72hrs until the end of the run and also from 57hrs the PV looks split until 204hrs, quite astonishing!

Nice heights in the artic at 141hrs!

[Liam J]

http://www.wetterzen...s/Rtavn3001.png!! The whole of FI is basically reverse zonality, however amusingly those blue 850's never reach us throughout

Depressions heading west over the Atlantic into the States! Nice 1060mb high over Greenland on that chart as well.

[Zenarcher]

A very nice 18z run there will be interesting to see the ensembles later.

[Snowy Easterlies]

only the Nogaps but blocking is further north and west compared to the 12z run

[Stu_London]

Pretty solid looking 18z for coldies.

Temperatures in the reliable part of the the run quite a bit lower than the earlier output but still all looks a bit marginal for lying snow.

Any accumulations will also be attacked from below as soil temperatures remain fairly high in the absence of any moderate or severe frosts yet.

Amused that on the last frame (+384) the GFS seem to suddenly remember which way the earth is rotating!

Edited November 22, 2012 by Stu_London

[Isolated Frost]

GFS 12z vs. ECMWF 12z at D8- the main 2, and best verification at D8 for both.

One major difference- a difference that makes everything else turn elsewhere- the Arctic High- the GFS smoothly rolls it s'wards into scandi, whilst the ECM sees a shortwave ejected from greenland, which stops the Arctic High from progressing- it simply slides down into russia- sliding a southerly flow into scandi and resultant waa.

The major point of the first spell will be the shortwave ejection out of greenland- where that lands will decide ridging, troughing and anything in between- the H5 pattern is set in stone for at least this first spell- the minor details will determine whether our TINY (!) isle get the full fruits of the glory of the charts we are receiving

[Chess01]

Is the 384 anything to worry about

[NickR]

Is the 384 anything to worry about

384 is never worth either worrying about or getting excited about. Because it's at T+384.

[LomondSnowstorm]

Is the 384 anything to worry about

The +384 is never worth worrying about.

[SE Blizzards]

Well, another day passes of model watching and i for one can say that overall i'm very happy with the way things are shaping up for the start of winter! A couple of things come to mind... PV in pieces and....... BLOCKING!!! Hopefully tomorrow will bring more of the same.

[johnholmes]

The gfs18z operational at day 10 is a good match for the naefs for the same time-scale,so looks

more plausible than the ecm.

18z.. naefs..

If you then compare the NAEFS outputs to the ECMWF-GFS and NOAA, and if they all agree then you have a fairly solid prediction available. If they do not then there has to be uncertainty for that time period. Take all the data you can find and from whatever source. If they all show a similar pattern then the more likely it is to be near the mark.

NEVER take one run, even one days' run for one model no matter which model it is. Do that and you will avoid the highs and lows seen pretty much all the winter period in the model thread. If you like the excitement and the ups and downs then that is fine. All I would ask is that when the models don't show what you want PLEASE DON'T moan in here, there is a thread for that?

[Stu_London]

Is the 384 anything to worry about

If you were referring to my post - did i sound worried?

[bluearmy]

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=london

Coldest ecm suite for a few runs. The op on the cold side days 8 and 9.

We are looking at a cold first week of winter. Mean maxes in the capital around 3c.

[Chess01]

If you were referring to my post - did i sound worried?

yes i no its fi and will change but on the past few runs at 384 there has being a break down of pressure over greenland

[Matty M]

The major development in the T144hr timeframe today has been the shortwave that develops between Iceland and Greenland around T120hrs....... It could be a major problem getting this cold spell off the ground.

I remain very cautious, tomorrow it could all go wrong.