Model Output Discussion - Spring Has Sprung

[Dennis]

EC 0z

[IDO]

A west-based trough is the worst kind of weather at this time of year (EC 850s):

It is a waste of a potential cold spell. So from D6-7 GEFS for London highlights average 850s as the trough moves in and dominates the FI to D16:

 

That Russian/Siberian block to the east has been a killer this year for our winter. Rubbish end to another very poor winter (snow-wise).

[Dennis]

 

[Purga]

Looks like coolish, wet & probably stormy at times with no frost at all - whoopee

 

[Dennis]

maybe.....

some changes are into the charts these days for late febr

[TillyS]

Not a lot of change in the models at the moment, except that the Iberian high which has plagued UK cold lovers all winter, is further west back into its resident Azores location. This ‘should’ allow for a more westerly to north-westerly flow over the UK with occasional northerlies. This indeed is now showing in the latter stages of both the current GFS and ECM outputs.

Which coincides with March. Technically, not winter but can still be a cold month and it could pep up life for the Scottish ski industry in the run up to Easter.

[ANYWEATHER]

28 minutes ago, TillyS said:

Not a lot of change in the models at the moment, except that the Iberian high which has plagued UK cold lovers all winter, is further west back into its resident Azores location. This ‘should’ allow for a more westerly to north-westerly flow over the UK with occasional northerlies. This indeed is now showing in the latter stages of both the current GFS and ECM outputs.

Which coincides with March. Technically, not winter but can still be a cold month and it could pep up life for the Scottish ski industry in the run up to Easter.

Indeed Tilly. Looks like the Atlantic is by and large the winner, although winds swinging into a more northwesterly,so hills and mountains seeing some wintry stuff especially northern hills....Plain rain for others although southeast Britain should see the lions share of any dry weather. Yesterdays models looked more cyclonic than they did today ,so still plenty of umph in the jet, but it does look like Winter this year will go even without a wimper !

[johnholmes]

Well a long time since I created a post using the usual models ( 2 Feb the last times)

In brief for approximately 23-27 February all 3 are on the same page. They show a marked upper trough over the UK edging slowly east and warming out slightly. On the surface ECMWF shows a deep low just south of Iceland on day 1 (27Feb), NOAA shows a marked 500 mb trough over the UK from a flabby sort of main trough NE Canada/NW Greenland by 26 February. UK Met 20-22 February shows a similar pattern with a marked upper trough and surface feature over the UK.

NOAA has contours on its 6-10 over the UK from about 520-534 DM north to south over the UK. So cold by the average expected for late February. ECMWF shows a quite strong northerly pulling in the cold air, surface and at 500 mb. UK Met by its last date (22nd) shows a strong NNW’ly over the near Atlantic with a rather flabby low over the Northern Isles and a high west of the NNW’ly flow.

Further ahead ECMWF indicates an upper ridge moving east into the SW along with a surface high a bit west of 20W at the same latitude as northern Spain.

NOAA with its 8-14 day chart has a +ve height anomaly of 150 DM or so in about the same place as the ECMWF surface high.

These charts would suggest that by the 27-28 February the cold air supply is being cut off. Probably by next Saturday ‘deepish’ cold air will be covering most parts, say -4 to -5 C at 850mb. I would think these conditions lasting until about month end?

Just my take on the outlook!

I'll try and post the charts I used to arrive at this

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

[Rain All Night]

22 hours ago, Rain All Night said:

0z deterministic runs, Fri 16th to Fri 23rd (day 7)

I guess we are looking for a steeper northwest-southeast gradient on the back edge of the trough for greater interest later, so the UKMO would be the pick here.

I would be interested to hear from any members with more of an interest in the finer details as to just how wild & windy it could get under the big purple blob later next week.

0z ensemble means, Fri 16th to Sat 2nd (day 15)

The trough still looks to be the main influence over the UK from 22nd through 26th. Still a chance of a slightly cooler flavour as the ridge builds in behind it around the 26th, but the more settled-looking mean from that date does not now remain for very long, and the ends of these runs leave us with the impression that there could be more weather coming from north of west later.

0z deterministic runs, Sat 17th to Sat 24th (day 7)

0z ensemble means, Sat 17th to Sun 3rd (day 15)

[Ali1977]

Some snowy ens fir later next week, probably high ground restricted for lying snow but you never know. This one looks good 

 

Edited February 17 by Ali1977

[WYorksWeather]

Still interesting to see the slight differences between the GFS and ECM 00z ensemble runs.

GFS still wants to make a little more of the colder than average spell, and has it lasting from around 23rd-27th, whereas ECM has it really as a 48-hour wonder.

In either case, though, surface temperatures never really dip below average by all that much - daily means usually hovering around the 5-6C mark in the south which is around average, and possibly trending back above average if the GFS is right.

The search for cold is just pretty demoralising by this point, so we might as well have one of those runs from near the top of the ensemble come off. Something like the GFS P10 from 06z looks nice at T+240. Still not quite enough to get the warmer, drier weather to everyone, but should still be fairly pleasant, benign weather under that ridge for a few days across a decent chunk of England at least.

 

[MATTWOLVES 3]

Hey folks I'm sure many of you have given up the ghost by now,and that's understandable! I've never seen a winter where the NWP as been so poor regards to blocking...I've probably lost my cool at times with it and slandered the teleconnections experts which I would like to apologise for! Basically it's been a nightmare from all the data to nail this down,and it's certainly not the fault of the experts who bring those really insightful and cool background driver updates. 

It appears a few spanners have been thrown into the works this winter,firstly perhaps El nino was a little to strong and a as a result we ended up with vast warming of some of the oceans which helped to inflate those iberian Heights...perhaps even the tongs eruption had an affect on the cooling of the stratosphere! There's multiple variables we can blame here and its a difficult post mortem tbh. The Canadian warming I feel also seemed to alter the structure of the PV and it acted up ever since..warmings from the bottom up etc.

Is it too late to save what's left of winter? Well tbh I'm old school and base everything on the equinox and say winter does not end till 21st March...so basically we have a very brief reversal die in the next couple of days before a quick uptick. Will it be long enough to reverse us to an Estly? Will it impact the trop? Many say know it won't and some have pointed out the wave acteas not strong enough. But let's be honest here the strat had been a forecasters nightmare this winter so don't be suprised to see more fun and games.

Last nights zonal winds also hint at yet another hit of the strat by early March,but we need to tread cautiously as these zonal wind forecats have left alot to be desired this season. What I will say I'd I'm noticing alot of ensembles now pointing to Ural blocking,a gr8 wave 2 precursor which makes me belive the strat may tumble quite abruptly rather than a customary slow breakdown at this time of the year..this could put us in the game for a cold and blocked 3nd part of March! Is it to late though? Well there's a lot of cold bottled up over the Arctic so a sudden breakdown could put us in the game. Remember last March! Some had a foot of snow! 

And I would like to finish by saying I wish you all well and have greatest respect for many of you..I've currently been spending a lot of time on X just to grow my followers.. its the same old me though..serious forecasts injected with a lot of humour! And on a sad note its been over 2 months now since my dad passed away,his ashes are now with us and there's not a day goes by when I don't feel bloody awful about his demise. To see it was shocking and will haunt me forever. I only hope he's ina better place now.

Go on gang have one last chase...its along time till next November! I wouldn't long drawn out severe cold...but I feel snow chances will crop up next month.

Loves ya brothers and sisters.. stay well and enjoy life everyday as its a long time gone!

[raz.org.rain]

 WYorksWeather the general theme has been for the milder outcomes to verify, even if they start out as outliers. When milder runs start turning up, assume something closer to them will end up coming to fruition.

[damianslaw]

Not much to add to yesterday's musings. The models firm on a change to a more westerly/north westerly airflow as we move into the latter stages of the month. Heights to our south west will be pulled west thanks to a deepening of the long wave atlantic trough and a switch in the position of the jet gradually becoming more NW-SE aligned.

What this means, is a very unsettled outlook in the main, and preety wet for most, becoming windy as well. Temperatures trending down to near normal levels by the 22nd.. risk of wintry precipitation northern high ground, very limited frost though thanks to few clear spells, sadly also a lot of cloud, but probably sunnier once polar air is injected in the mix.

As we enter Spring, the chances of 'cold synoptics' increase markedly traditionally, northerly arctic shots often occur and easterly outbreaks and cold cyclonic spells, not saying we are on course for such conditions this spring, but typically the atlantic and the azores high often finds it more of a battle to dominate than in any other season.

[Dennis]

 

[Tim Bland]

Welcome to Spring

[Daniel*]

One thing for sure it’s going to feel markedly colder after all this much milder weather. The skiers in Scotland will be delighted by outlook. 

[Daniel*]

T168 looks rather slidey there, it can still be possible to see a snow event from an unremarkable cold set up. Low heights/thicknesses help.

[Dennis]

a patterchange may build up into next week (end)

see NOAA chart

 

Edited February 17 by Dennis

[WYorksWeather]

Right, on with tonight's post.

Ensembles and means

Still interesting to see that compared to recent weeks where we've seen a lot of uncertainty, the 12z ensembles are very stable looking. There are very few notable ensembles, either mild/warm or cold. It really does look like the exceptionally mild weather comes to an end, and then we hover around average at the surface. Maybe early hints of a return to something more spring-like for early March, but way too far away to be sure of that.

It makes a lot of sense when you move over to look at the day 10 means. Both GFS and ECM have a fairly active Azores high (more so ECM), but it has dropped back west from its position more recently over Iberia, so it's not really well positioned to draw up anything notably mild for the UK. However, we also have a distinct lack of any real blocking, so nothing to drive a colder pattern.

The result is probably various shades of westerlies - the mean flattening things out, but I think in reality probably a series of changes from cooler north-westerlies to milder south-westerlies until something comes along to change the pattern. Unfortunately we're not close enough to the high so the result is probably a lot of flat westerlies bringing in wind and rain from the Atlantic. 

SSTs

SSTs at days 0, 5, 10, and 15 continue to show that the clock is ticking on winter. Not much change from days 0 to 15 now.

 

Zonal wind

ECM still going for potentially an early final warming in the first couple of weeks of March. Not clear yet what will happen as a result. The earlier SSW due around the 20th February looks like a brief reversal followed by a rapid zonal wind recovery. It will probably need to wait until we're past the first SSW to get a handle on the final warming.

Summary

Fair bit of model agreement I think on a fairly run of the mill period temperature wise. Unfortunately not high pressure dominated which is what I think would be preferable given all the recent rainfall. There is some hope, however, that we may get some transient ridging to at least give us a few dry days from time to time.

Not much hope of an early warm spell or any late season cold at the moment.

 

[feb1991blizzard]

 Dennis

The 850 windflow chart don't look special to me, don't you need a thicker band of continual Westerlies nearer to 180 degrees?

[carinthian]

 Daniel*  I just hope that charts comes to fruition next week. Currently , over here in Austria heading for the warmest February ever ! Yesterday saw a record 13.9 c recorded at 2400m , the warmest at that elevation for February  since 1961 . Quite widely 19 c recorded at 400m on Friday. No wonder when 37c plus being recoded during this month in Morocco. Something very wrong !

C

[feb1991blizzard]

looks a very weak unfavourable .MJO signal

[Met4Cast]

 

On 14/02/2024 at 13:23, Met4Cast said:

There's no real sign in this fluxing switching to poleward fluxing and as a result there isn't much forcing to amplify Atlantic ridging into high latitude blocking later this month, hence the forecasts (and this is well represented within NWP modelling) generally favouring an amplified Atlantic ridge sending energy SEwards, for the UK this will likely bring colder weather than the anomalous warmth we've been seeing/will see in the coming days but probably wont be enough for a notable cold spell or widespread snow risks. 

I think a good way to see how thing are progressing is to check previous posts so I've quoted this over from the teleconnections thread. Broadly this is how things are heading. 

Certainly turning colder as next week progresses but for most not cold enough to produce snowfall to lower levels. Further ahead into March is rather complicated, the RMM MJO plots are proving rather useless currently but viewing the VP200 anomalies seems to suggest a decaying MJO signal into the COD through phase 8 before a resurgence into phase 5/6.

Broader westerly momentum continues to rise as yet another +EAMT begins to take hold which perhaps gives some confidence to the current modelling re: another stratosphere u-wind reversal early - mid March, an early final warming perhaps? Too early to say. 

Given this, I'd not be surprised to see a -AO and perhaps trending -NAO towards the middle of March. Blocking patterns potentially finally taking hold, once again, too late?

[feb1991blizzard]

 Met4Cast

I can see a big neg nao happening final third March - totally strat related. got a feeling it will be a warm Easterly though.