Winter Model Discussion 18Z 16/1/13 onwards.

[Timmytour]

The GFS resorts to a slingshot of lows being fired under the low south of Greenland to attack the cold and eventually they start taking a nore northerly route as the Jetsream moves north and break through. But if they keep staying on the same track as earlier in the run, it could lead to undercut after undercut. It's a disappointing looking run from around T132 but it's not a million miles away from being an absolute belter either!

[nick sussex]

The latest UKMO fax charts are out, they go with the raw output:

T96hrs:

T120hrs:

Given the model disagreements these are bound to change but for tonights quiz question what is unusual about both of these given what you might expect to see?

[Jason M]

And at 300 hours GFS has managed to fully revert to the 'pancake'. Who would have predicted that??

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=300&mode=0

I'm interested in what the ensembles show out to day 7, but little point beyond that.

Jason

[johnholmes]

The voice of sanity.

John — OOI when will we be officially able to speak of Jan/Feb 2013 in hushed tones like '47, 62/63, 2010 (which seems like a blip compared to the other two) — what's the criteria? Records broken, longevity, snow amounts, general chaos?

1 March!

I personally feel that this winter will in no way compare with 47, 62-63, 2010 Nov-Dec is about a 20% prob at the moment

[Ice Day]

The latest UKMO fax charts are out, they go with the raw output:

T96hrs:

T120hrs:

Given the model disagreements these are bound to change but for tonights quiz question what is unusual about both of these given what you might expect to see?

I can't see a Bartlett?

[Col Berkshire]

The latest UKMO fax charts are out, they go with the raw output:

T96hrs:

T120hrs:

Given the model disagreements these are bound to change but for tonights quiz question what is unusual about both of these given what you might expect to see?

Usually we would expect rain from this set up, but with the 528 dam line well below us, I'm guessing it will deliver snow??

[The Weather Dragon]

The latest UKMO fax charts are out, they go with the raw output:

T96hrs:

T120hrs:

Given the model disagreements these are bound to change but for tonights quiz question what is unusual about both of these given what you might expect to see?

Reverse zonality

[blizzard81]

I can't see a Bartlett?

You beat me to it, my thoughts exactly.

[weatherguy]

May I ask why you're all looking into deep FI? Remember the progression of LP systems has constantly been over-modelled as they fail to get to grips with the negative tropospheric winds which slows the momentum down to a point where they are consistently being beaten off by our block; the same thing has happened consistently for the last week, and I would expect it to continue, with them being pushed further south as we come into the reliable.

Think of running into someone who pushes back, you'll likely push over the person at the end. Run up a steep hill (the negative tropospheric winds) first and the person at the top is likely to be able to push you back!

[nick sussex]

Usually we would expect rain from this set up, but with the 528 dam line well below us, I'm guessing it will deliver snow??

Yes you're right its unusual to see the 528dam that far south with that type of set up however regardless of that you will have a change of airmass behind the occlusion on the T96hrs so even with that sub 528dam you'll still end up with too much modification.

It won't be mild just less cold and of course theres little chance of those fax charts verifying like that given the model disagreements .

[Froze were the Days]

what do we make of the 120 hr fax chart?will it go south or mix out the cold air

looks very likely to mix out the cold air, far north (Scotland) might fair better but unfortunately there's no undercutting there. The FAX charts look quite different to the GFS though at that stage so maybe all to play for on maybe colder conditions coming back unlike the GFS.

[pages]

Think we will know either way if the block is going to break next week by this time tomorrow, we only need slightly higher heights into greenland and that low will be further south, so eject more energy south east, reinforce the block and stop that awful azores high poking its nose in.

No point looking past T90 on next run. just look at t90 t84 t78 t72 over the next 4 runs and hopefully see the trend for the azores to be displaced further south. if its not thats the block gone.

Wont be to sad, loads of snow over next few days and with the vortex in trouble the next cold period may not be far away.

Anyone got a link to the GEM 18z its stuck one t120 on metociel should go 144. Shows close to what i think above but probably still slighty north. Nogaps is cottoning on.

Expect a 50/50 split on the 12z tomorrow between showing continuation of cold (brief thaw for south around t168) and thoose showing the atlantic break through.

[The Enforcer]

Yes you're right its unusual to see the 528dam that far south with that type of set up however regardless of that you will have a change of airmass behind the occlusion on the T96hrs so even with that sub 528dam you'll still end up with too much modification.

It won't be mild just less cold and of course theres little chance of those fax charts verifying like that given the model disagreements .

Doesn't it end up being a battle between polar maritime (return) air and polar continental air with -528dam on both sides of the battle?

[Frosty.]

They will self destruct in 5 seconds

Yeah well it's certainly been mission impossible to get a decent gfs run today although the gfs 00z was showing an increasingly anticyclonic spell and remaining very cold but really the 6z, 12z, and now the 18z have been disappointing from next tues/wed onwards.

Night all, model fatigue has finally got the better of me, i'm blaming the gfs

[Weather-history]

By the way this is what GFS 18Z , 144hrs ago was suggesting for today

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=144&mode=0&heure=18&jour=11&mois=1&annee=2013&archive=1

Where's the snow event threat?

[Tim Bland]

The latest UKMO fax charts are out, they go with the raw output:

T96hrs:

T120hrs:

Given the model disagreements these are bound to change but for tonights quiz question what is unusual about both of these given what you might expect to see?

The position of the 528 Dam line in relation to the depression / front. V rare for the uk..bring on the snow!

[Jason M]

Ensembles are very odd. Some really good set ups out to day 5, then they all just start to revert to type after this point. Even if GFS was correct on the end game the speed with which the pattern changes to a normal winter pattern is just too progresive.

Jason

[Chris W]

Deary me, no wonder no one is comenting on the gfs 18z!! Mild fest!!

Quite possibly because a ) we're all preoccupied with tomorrow and b ) with the current and likely forthcoming synoptics of negative mean zonal winds, a split vortex and cold air feeds everywhere the breakthrough of the Atlantic as modelled by the GFS in FI is pretty much unbelievable. The GFS is seemingly on its own vs the UKMO, ECM and the rest and still struggling to deal with the SSW effects and subsequent cold.

Edited January 17, 2013 by Chris W

[Iceni]

http://www.meteociel...arte=2000&ech=0

Look at that lovely little front whacking into East Anglia at T72!

[Nick F]

Although I don't think this cold spell will be erased no-where near as quick as the GFS operationals suggest, I would prefer to see a much stronger height signal over Greenland than what is currently indicated by the models.

Always the threat, especially from GFS, that the PV edging east from NE Canada and across S Greenland may spoil the cold party more sooner than we would like without the ridge retrogressing over Iceland and Greenland.

However, at least the 12z ECM and UKMO ops do hint at height rises W/NW across the GIN corridor to our north t+96-144;

Edited January 18, 2013 by Nick F

[yorkieblade]

Look at that lovely little front whacking into East Anglia at T72!

East & West Attack T72 Fax? ...............Great Avatar btw

[BLAST FROM THE PAST]

Something to chew the fat over. Scandi has temps of MAXIMA -20c this weekend...MAXIMA. Now look at the chart with the finger of green and light blue uppers

Look at 850s over Scandi for this weekend, stop worrying....over our snowfields temps will be seriously low so come Mon any 'mild' sector will NOT reflect surface temps. Bitterly cold to remain

BFTP

Edited January 18, 2013 by BLAST FROM THE PAST

[swfc]

upgrade of sorts on 0z medium term.i still think the outlook is far from certain post 92 hours

[Cecil Hogmanay Melchett]

gfs/ukmo now bringing the breakdown into the 144h radius,looking at the nh plots on ukmo you have to wonder whats going on with this SSW beacause at face value you would say the strat is freezing cold,its a poor profile with little or no HLB to be seen!!

[Jason M]

gfs/ukmo now bringing the breakdown into the 144h radius,looking at the nh plots on ukmo you have to wonder whats going on with this SSW beacause at face value you would say the strat is freezing cold,its a poor profile with little or no HLB to be seen!!

Yep, I agree. I've just looked through the runs myself and they are starting to look a bit GFS like. The ensembles are really poor and I can't find a single chart anywhere this morning with heights over Greenland. The PV just sits there and in response the AZures high builds and forces us back into a zonal pattern.

Its all still at day 6 but its a strong signal this morning. Be interesting to hear from Chio or GP as this seems against the background signals. I've been pretty much ignoring anything with a strong PV as nonsense but I'm not so sure this morning as I sense the models are just starting to sort themselves out.

Still, lots of snow to enjoy and its a long way off still.

Jason