Model Output Discussion 31/03/14 onwards.

[knocker]

I'm not so sure the ENS is quite so optimistic SS. Mind shouldn't pin much on it yet anyway.

 

 

[BlueHedgehog074]

Not a bad update from the GFS 06Z model, I must admit. It's one of those 'it-has-something-for-everyone' runs. Rain, showers/thundery showers sunny spells, cold days, warm days, High Pressure dominated days (mostly FI), Atlantic/channel Low days, wintry Northerlies with possible sleet and snow, frosts, warm(ish) South-Easterlies/Easterlies etc. The only element this run seems to be generally absent of is a Westerly/South-Westerly flow mostly thanks to Northern blocking and a Southerly tracking Jetstream which isn't particularly strong and flat.

[Polar Maritime]

Not a bad update from the GFS 06Z model, I must admit. It's one of those 'it-has-something-for-everyone' runs. Rain, showers/thundery showers sunny spells, cold days, warm days, High Pressure dominated days (mostly FI), Atlantic/channel Low days, wintry Northerlies with possible sleet and snow, frosts, warm(ish) South-Easterlies/Easterlies etc. The only element this run seems to be generally absent of is a Westerly/South-Westerly flow mostly thanks to Northern blocking and a Southerly tracking Jetstream which isn't particularly strong and flat.

 

Aye, A very traditional end to April and start of May coming up.

 

The latest meto update is not a million miles from this mornings GFS, and as JH has put also in-line with noaa.

 

http://forum.netweather.tv/topic/64157-meto-uk-further-outlook/page-83#entry2959824

Edited April 23, 2014 by Polar Maritime

[johnholmes]

my comment on the latest Met O 6-15 day supports the idea of a coldish and unsettled end of month outlook.

[Polar Maritime]

Yes John, to be honest i think the models have handled this upcoming cooler/unsettled spell pretty well this time around.

[Summer Sun]

The London, Manchester and Aberdeen 06z ensembles this afternoon are all showing a rise in pressure from later next week which should help to start and settle things down as we approach the next bank holiday weekend

 

 

The 850's on them all go above average from the 4th / 5th onwards

Edited April 23, 2014 by Summer Sun

[East_England_Stormchaser91]

I know it may not mean anything, but the current synoptics now do not look that dissimilar to 1976! Just a thought! 

[IDO]

The London, Manchester and Aberdeen 06z ensembles this afternoon are all showing a rise in pressure from later next week which should help to start and settle things down as we approach the next bank holiday weekend

 

 

The 850's on them all go above average from the 4th / 5th onwards

 

Yes the Op and also the control leading the way at D10 for a pressure rise. Interestingly the 06z GEFS don't currently support these, with only two other members having HP over the UK. The UK trough still unchanged from the last few runs with 50% of members supporting that, whilst about 35%  go for a mix of the two; the UK caught between the two synoptics. The mean highlights this:

 

 

The ECM mean at T240 also favouring a UK trough though the South not far away from higher pressure:

 

 

The GEM mean at D10 also similar to ECM and GFS: 

 

So despite the Op & Control, HP trending down compared to yesterday for D10+, however lots of uncertainty so sitting on the fence for the moment. Around 7 days of cooler more unsettled to come from Friday then maybe a brief ridge before further slack flows of lower pressure, is my take on it (as the vortex slowly fades).

Edited April 23, 2014 by i'm dreaming of...

[Weather Boy]

I know it may not mean anything, but the current synoptics now do not look that dissimilar to 1976! Just a thought! 

 

Hmmm, not wishing to rain on your parade, but I recall similar comments before the summer of 2011 (I think it was) on this forum.

 

That one didn't work out!

 

Experienced members say that pattern matching is a mug's game - surely that applies double plus when looking to match patterns months rather than weeks ahead?  (I acknoweldge that I am making the wild assumption that you are alluding to a possible repeat of summer 1976 as opposed to say, late spring!)

[Summer Sun]

Still differences between GFS and UKMO at t144 if UKMO is right the SE would hold onto the milder air for one more day whereas GFS would bring lower temperatures for all with wintry showers in Scotland especially on high ground

 

 

Longer term GFS remains keen to build pressure later next week and into the following week

 

Edited April 23, 2014 by Summer Sun

[Captain Shortwave]

Very very complex set up developing this coming weekend as heights build in the Atlantic and into Southern Greenland. The confusion is on the strength of the jet and how much energy cuts through the ridge in the Atlantic. The UKMO has more push forcing the low affecting us this weekend to drift into Central Europe and the low heights moving south west from the Pole phase with the Atlantic low giving a milder solution (though a northerly would possibly happen later). The GFS phases this polar energy with the low over the UK this weekend and sets up a potent northerly plunge early next week. Very small margins give big differences even in the semi-reliable timeframe.

After that there are signs of pressure rising during the first week of May as the next Atlantic low positions itself quite far south which in turn will encourage the Azores high to build northwards into Southern Europe. Though we are long way off from resolving that at the moment.

 

Edit - To add more uncertainty, the GEM delays any cold plunge even further to the end of next week.

Edited April 23, 2014 by Captain shortwave

[Summer Sun]

Well then GEM has just made this colder plunge at the start of next week even more uncertain now with the cold air delayed till the end of the week

 

Edited April 23, 2014 by Summer Sun

[ANYWEATHER]

Gfs shows from both its outputs surprisingly, 06z and 12z something colder for all next week, with frosts and even some wintry stuff down south, when we get to day ten both gfs 06z and 12z show a rise in pressure which again is surprising given the time scale... :winky:  :winky: :winky:

Edited April 23, 2014 by ANYWEATHER

[Summer Sun]

ECM starts the week off with some milder air but its replaced by colder air mid week its also showing a rise in pressure by May 1st

 

 

Later next week high pressure starts to build

 

 

Still early yet but we now have both GFS and ECM showing a rise in pressure later next week as the high over Greenland starts to ease away

Edited April 23, 2014 by Summer Sun

[ANYWEATHER]

And the Ecm shows some sort of a colder shot next week! Nothing is nailed to detail , but ecm and gfs are showing something similar! :winky:  :winky:  :winky:

[William of Walworth]

Out of my post-October hibernation! Glad I can remember my password. Thanks for all the recent analysis. 

[Milhouse]

Out of my post-October hibernation! Glad I can remember my password. Thanks for all the recent analysis. 

 

Welcome back!

 

Models have a bit of everything tonight. Residual warmth dying away, leaving a rather cool and unsettled spell before signs of high pressure nudging back in from the west. No sign at the moment of the jet stream roaring into life bringing an endless train of southerly tracking low pressures. So something to be positive about.

[Winter Cold]

It seems to be odds on now that we will see a colder period next week to me, both GFS and ECM showing this in around a weeks time from now on tonights runs. Id enjoy some final frost and to see a few snow flakes

 

GFS:

 

 

ECM:

 

[knocker]

Taking this weekend as a write off some attention to the following week and that weekend. Regarding the upper air at the moment the GFS has cold air dominating the eastern Atlantic and UK giving still unsettled conditions. A glimmer of change by Saturday with a ridge building and warmer air becoming the predominate feature.

 

ECM going for unsettled in mid week but with the cold upper east air moving also has a build up of heights over the UK but will it stay like this?

Edited April 23, 2014 by knocker

[knocker]

Well as they use to say at work, "belay that last pipe".

Edited April 23, 2014 by knocker

[reef]

That would certainly be a shock to the system:

 

 

-7C 850hPa isotherm right down to Northern England would mean any showers would fall as snow to low levels with massive temperature dips during showers.

 

Temperatures the next morning would be lower than some places had all winter:

 

 

It would almost certainly be the most potent May cold snap since 1979. Still 6 days out, but its creeping closer and has some support from the ECM tonight:

 

 

Definitely one to watch. Can it do what no winter cold snap managed this year and make it to T+0?

[knocker]

A quick look at the GFS ens for !8z en passant

Edited April 24, 2014 by knocker

[Captain Shortwave]

Still evidence of heights building close to the UK during week 2 as low heights clear away north eastwards.

 

ECM still going for this too, but any details look sketchy as the evolution from this weekend onwards is still up in the air

 

GEM also has heights building in around this timeframe too. So some kind of chilly arctic blast before conditions settle down again perhaps.

[Summer Sun]

GEM once again this morning delays the coldest air to later next week

 

 

-4 is about the lowest the 850's get to on GEM away from Scotland

 

 

ECM is also delaying the colder air now to later next week

 

[Thundery wintry showers]

I think the odds are that this northerly outbreak will be too watered-down to bring widespread snow showers- the main factors being a strong build of pressure to the north and north-west, and troughs moving from west to east across the south, introducing more of an easterly flow.  Most model outputs are going for a weak ridge of high pressure into the first week of May, with dry sunny weather and some night frosts for the north and west of the country although the east and south of England may be more prone to cloud and belts of rain.

 

The NOAA 8-14 day updates and ECMWF ensemble mean are suggesting that an Atlantic trough may drift eastwards during the first week and produce warmer and more changeable conditions later in the first week of May:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php