Model output discussion - 20th Feb onwards

[winterof79]

Squall line setting up over Northern England on the radar if anyone's interested.

[snowray]

Ideally we want the Euro LP to swing back up north, we have seen that on some recent runs.

[mcweather]

Don't forget as per Ian F'S post earlier that the operational models are behind the curve on this change to cold and are playing catch up, so I wouldn't be surprised to see some quite stellar charts coming out over the coming days. Especially with ( again as per Ian post) the projected storm tracking moving south of the UK.

[snowice]

12 minutes ago, snowray said:

Ideally we want the Euro LP to swing back up north, we have seen that on some recent runs.

Well anything past +72hours once wind goes to east north east cold uppers -8 should see snow at short notice .  

Edited February 21, 2016 by snowice

[SMU]

UKMO t72

 

shows the -8c line reaching the wash moving steadily south, it also shows a pretty large swathe of -10c air over scotland-

if ws then refer to the UKMO 96

 

then it would be feesable to assume that the -10c line may penetrate further south - all the way to the wash with the -8c/-9c line more widspread - perhaps to London by then.

That indicates that over the last 24/48 hours weds & thurs are progged to be colder than expected with Maxes of only 1-4c instead of 3-7 initially-

Sharp frosts will develop overnight-

Theres also a band of PPN crossing the UK at T72 heading SSE - could become more wintry.....

S

 

[bobbydog]

46 minutes ago, Steve Murr said:

Afternoon-

Lets not underestimate the 12Z UKMO

One of the best runs of the winter, more so because there is deep cold ( -8c) at T72 

At 144 the flow allignment means minimal mixing of Mild uppers from the ESE & another cold pool dropping into scandi for continuation of cold thereafter...

As said - the best run of the year because the cold is not +6 days away-

also plenty of snow opportunities - even in the far SW !

S

there is also the strong possibility that these charts could start to get even better if they are playing catch-up to the Glosea and EC monthly models with regards to the MJO. (as ian reported earlier).

despite what some think regarding it being 'too late' for significant snow, we still have a decent (big even) window of opportunity for a proper 'snowfest' and the chances are getting higher....

Edited February 21, 2016 by bobbydog

[Steady Easterly]

UKMO is beautiful, at this time of year the flow couldnt be better, Europe would be colder too from any resultant Easterly.

[Nick F]

10 hours ago, IDO said:

A cool week ahead for the south but no cold blast by anyone's play book.

These temporary amplified Atlantic ridges do not look like pattern changes from the last 2-3 runs, just the repeated attempt by the Azores to ridge North, thwarted by the PV lobe to the NW. So a couple of topplers in the next 10 days which was what GFS was charting 5 days ago. The difference is that it is a colder upper flow so we keep in a more seasonal temp spectrum. 

 

If recent runs are anything to go by, looks quite dry through much of the coming week after the rain clears south tomorrow morning and little rain in the far south on Tuesday. North of Scotland and east coast could see some sleet or snow showers though.

12z UKMO notably stronger with the Atlantic and Greenland ridge than GFS ... be interesting to see whether ECM shows similar to UKMO, as the extended EPS 500 hPa anomalies over recent runs has been hinting at persistent ridge anomaly over Greenland into the far N Atlantic - which goes against the last few GFS operationals which want to fill in this area with low heights as the Canadian and Svalbard 500mb vortices join up.

[karyo]

4 minutes ago, Steady Easterly said:

UKMO is beautiful, at this time of year the flow couldnt be better, Europe would be colder too from any resultant Easterly.

True, the further south the cold air gets the better in terms of avoiding milder air coming back from the east/southeast late next week.

[feb1991blizzard]

2 minutes ago, bobbydog said:

there is also the strong possibility that these charts could start to get even better if they are playing catch-up to the Glosea and Euro4 models with regards to the MJO. (as ian reported earlier).

despite what some think regarding it being 'too late' for significant snow, we still have a decent (big even) window of opportunity for a proper 'snowfest' and the chances are getting higher....

I think that's more likely to affect the medium range though, anything up to 5 or 6 days will just be fine tuning by the models (obviously can make all the difference with what areas get PPN / snow / rain) rather than the overall longwave pattern.

[goosey007]

Excellent charts this afternoon if cold is what your after....and just in the nick of time !! I await tonight's ECM with much excitement .....could rival 'THAT' ecm !!! .......

[The Northern Ramper]

58 minutes ago, chris55 said:

Trying to pick out ppn at 144 is simply futile IDO.

Often once the cold air is in situ ppn events pop up at T48 or even less.

Its the broad-scale pattern we should be focusing on.

And as the flow is from the east dew points are looking pretty good, as well as the 850s!!  

DP

He is a seasoned poster fully aware of what he posts, try not to rise to it.

[bobbydog]

3 minutes ago, feb1991blizzard said:

I think that's more likely to affect the medium range though, anything up to 5 or 6 days will just be fine tuning by the models (obviously can make all the difference with what areas get PPN / snow / rain) rather than the overall longwave pattern.

oh yes, i agree. the next few days will be roughly correct as far as model output goes. finer details will change as you say. after that however, is where we could see a change in the output to colder conditions. we just need precipitation to match.....

[Tamara]

Anyone remember the February 1983 template?

Suggestions fast increasing in current modelling that it might finally be arriving about 3 weeks later than anticipated back in mid January.

 

Mid January saw the last tropical/extra tropical coupling take advantage of a temporary disconnected troposphere/lower stratosphere with the cold mid and upper stratosphere - and provide the only below average amplified Atlantic sector spell (lasting a week) of the winter to date

The catalyst for pattern change to cold, is exactly the same one that was suggested in the regular postings at the half way point of the winter.   Its simply that the external stratospheric pathway hindered hopes of earlier vortex dismantling and also the expected speed of renewed tropical/extra-tropical coupling in the Pacific (to provide the Atlantic amplification in tandem with the now rapidly weakening vortex) has not come around as fast as anticipated.

The result - a delay in the reload of cold to the close of winter rather than the final third of the season as was envisaged.

Westerly wind bursts from the MJO orbit imprinting the Nino zone in the Pacific are more measured as would be expected at a late stage in this Nino's life-time, and also less pronounced as is usually the case in late winter Nino's - but the expected central Pacific forcing expected to develop in the second half of winter is developing nicely and sets the scene for end of winter/early Spring seasonal longwave adjustments to the upstream profile and changes to increasingly undercutting low pressure and evolving -NAO.

Its a pity it couldn't have happened earlier to help accentuate the cold potential, but then there has been a LOT going on with several complicated seasonal drivers to monitor.

Complicated maybe - but the Glosea5 model does seem to have called the winter pattern evolution very very well. Its stratospheric, ENSO and tropical forcing modelling has once again proved impressively accurate

[Daniel*]

Thames Streamer angle? The lows diving to the south of us have their pluses. I am just delighted we're about to embark on to some real winter weather, it has felt like an eternity..

[nick sussex]

Great UKMO tonight, the sort of output that's been missing for the whole winter.

Still interested to see whether the models will develop some frontal snow of that low dropping se. Initially they really blew this feature up but seem to be toning this down which does help.

The main thing is that once this drops se that the Euro troughing is located not too far west , this then stops any milder air being pulled nw from the Med.

[karyo]

A nice kink in the isobars at the 72hours ECM chart indicating an existence of a trough moving south/southeast from Scotland into northern England and the Irish sea.

[northwestsnow]

1 minute ago, karyo said:

A nice kink in the isobars at the 72hours ECM chart indicating an existence of a trough moving south/southeast from Scotland into northern England and the Irish sea.

Yes can see it, but will it  be cold enough K?

[karyo]

2 minutes ago, northwestsnow said:

Yes can see it, but will it  be cold enough K?

I would say yes as things are looking currently. Upper air temperatures around -6 with -8 following the trough.

[feb1991blizzard]

4 minutes ago, northwestsnow said:

Yes can see it, but will it  be cold enough K?

Easily cold enough for us 2, for once this winter its PPN that's the issue and not 850mb temps, dp's thicknesses etc!!!

[Nick L]

7 minutes ago, karyo said:

A nice kink in the isobars at the 72hours ECM chart indicating an existence of a trough moving south/southeast from Scotland into northern England and the Irish sea.

Negligible precip on it though...

[Chris.R]

7 minutes ago, karyo said:

I would say yes as things are looking currently. Upper air temperatures around -6 with -8 following the trough.

That doesn't sound good enough for with in 15 miles of the coast, need -9 at least if precip is light,   Unless there are other more  conducive parameters.  No point worrying about it yet I suppose. 

[Harsh Climate]

It seems a lot are getting way carried away. As nick says, on the evidence of most of the models next week looks cold but increasingly dry. 

It will take more than one good UKMO chart at 144h to change that, I doubt it will be there in the morning. How many phantom ukmo amazing charts did we see in januarys cold spell that offered so much but produced so little!

Encouraging post from Ian F earlier, but even with most of the signals pointing to cold/blocked weather that does not at all guarantee us SNOW. 

A few times we have had POTENTIAL this winter but has yet to deliver, we are looking at it all over again, more positively we are seeing the strongest signs for sustained cold/blocking but on the flip side, stronger sun/longer days and a serious lack of any deep cold pool over europe/scandinavia and even russia.

So I would strongly here to the side of caution and any appreciable snowfall for lowland england/wales is still a long way away!

Edited February 21, 2016 by Harsh Climate

[karyo]

7 minutes ago, Nick L said:

Negligible precip on it though...

Troughs tend to upgrade as we get closer to the event. Not always, but often the case.

 

[Banbury]

You have to laugh, its amazing what doesnt look too good, some are so hard to please

Feeling cold in a set up that we craved for, you never know what might crop up