Model output discussion - 20th Feb onwards

[NorthYorksWeather]

Mouth watering charts on the 18z for many parts, shows whats still possible, or is this GFS's last tease of the winter?

[johnholmes]

And to add to the pot, the NOAA 6-10 shows a flattish Atlantic flow with the 8-14 showing a more meridional type. I have rarely seen such a change between the two in one issue. So, maybe a more disturbed short spell sometime during the 6-10 day period and reverting to a more north of west flow after that. very interesting to see how this plays out and I will not be around to see it. yet another holiday! The ECMWF-GFS output in the morning will be interesting to see which way they trend.

The 12z issue from them showed EC back to a meridional flow and GFS retaining its meridional pattern.

The plot thickens!

 

[NorthYorksWeather]

Sounds good John! Do you have a link to the NOAA charts you speak of? Cheers

[feb1991blizzard]

1 minute ago, vizzy2004 said:

Sounds good John! Do you have a link to the NOAA charts you speak of? Cheers

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

[Nick F]

29 minutes ago, vizzy2004 said:

Mouth watering charts on the 18z for many parts, shows whats still possible, or is this GFS's last tease of the winter?

Although GFS has shown nationwide snow potential later next week for a few runs now, I still remain sceptical of significant or widespread lowland snow events for southern UK from a NWly , they rarely verify, but GFS does seem to have a cold bias at that range before watering down nearer the time. That said, an unstable NWly flow as progged could see brief snow fall to lower levels in any heavy convective showers with cold downdrafts pulling down the freezing level. Looks wintry for the north though, with plenty more snow for Scottish skiers.

18z GFS just another variation on the general theme of deep troughing persisting over Europe - ridging to the west over the Atlantic building north toward Greenland and Iceland at times, jet diving S or SE from Greenland toward SW/W Europe, UK in chilly to cold W to NW to occasionally Nly flow. Any milder incursions from the west short-lived. Potential for snow events later next week too early to consider for now. North always favoured more than south.

 

Edited February 25, 2016 by Nick F

[fergieweather]

Effectively all of March in latest EC Monthly is signalled as chilly under northerly-sourced flow, with pronounced +ve MSLP anomalies growing widely to N (esp NW) after mid-month. All in all, it looks like we will see disappointingly depressed temperatures for the start of Spring, with protracted risk of frost. 

[Abyss]

After the exceedingly mild Winter I'm happy with it being a cold start to Spring

[KyleHenry]

3 minutes ago, johnholmes said:

And to add to the pot, the NOAA 6-10 shows a flattish Atlantic flow with the 8-14 showing a more meridional type. I have rarely seen such a change between the two in one issue. So, maybe a more disturbed short spell sometime during the 6-10 day period and reverting to a more north of west flow after that. very interesting to see how this plays out and I will not be around to see it. yet another holiday! The ECMWF-GFS output in the morning will be interesting to see which way they trend.

The 12z issue from them showed EC back to a meridional flow and GFS retaining its meridional pattern.

The plot thickens!

 

Hi John, I follow the NOAA but that can be further improved upon by following pattern further upstream. 

East Asian mountain torque event from 48hours ago. With Aleutians low pressure moving position amplifying pattern which is now interacting with the Rockys. That will produce more upstream amplification within next 48hours in Atlantic region. Charts will then change in accordance. 

[NorthYorksWeather]

3 minutes ago, fergieweather said:

Effectively all of March in latest EC Monthly is signalled as chilly under northerly-sourced flow, with pronounced +ve MSLP anomalies growing widely to N (esp NW) after mid-month. All in all, it looks like we will see disappointingly depressed temperatures for the start of Spring, with protracted risk of frost. 

It certainly would be disappointing to see ideal winter sypnotics in March that are too marginal for the snow that most members on here crave. As Nick pointed  out above GFS has a tendency to downgrade uppers as the time gets nearer, which could mean the diffence between snow at sea level and instead restricted to high ground. Here in the North Yorks I'm quite optimistic I will at least get my snowfix in the hills over the next few weeks, anything down to my elevation will be a bonus. 12z EC det looks rather wintry across the North next week with low pressure never too far away and uppers 850s around -4/5c.

[feb1991blizzard]

This just illustrates how brutal cold can build close to us even I'm March from a situation that looks hopeless.

[NorthYorksWeather]

18z ensembles backing up many posts tonight with regards to a chilly start to Spring, after a brief mild blip early next week the mean 850s for my area sit below average for the rest of the run. 

Edited February 25, 2016 by vizzy2004

[Singularity]

20 minutes ago, KyleHenry said:

Hi John, I follow the NOAA but that can be further improved upon by following pattern further upstream. 

East Asian mountain torque event from 48hours ago. With Aleutians low pressure moving position amplifying pattern which is now interacting with the Rockys. That will produce more upstream amplification within next 48hours in Atlantic region. Charts will then change in accordance. 

Good spot Kyle, I continue to anticipate increased amplification which may serve to improve the draw-in of cold air later next week and beyond.

There are a great many on here who could do with shaking themselves clear of the idea that snow of any description is out of reach for southern UK this coming March. The bigger issue is getting any to settle or stick around during the daytime.

The best outcome exploits the boost to convective features that the stronger sun brings to produce an onslaught of heavy snow showers at a rate great enough to overcome the daytime thaw... a rare but beautiful beast (as you get to see the results in daylight for much longer at a time than in the depths of winter). With diving troughs into Europe and - potentially - some more significant cold air encroaching from the NE toward the end of the first week of March (compared to what we've seen through the majority of the winter), there has to be a chance for eastern parts in particular - but this is just a possibility at this stage so no need for anyone to get excited or panic.

In terms of 500 mb and surface pressure patterns, March 2016 may well be among the more spectacular of the past century, but for the air temperatures to follow suit across the UK and NW Europe (as in be spectacularly cold for the time of year), there would have to be an import from central parts of Asia where it actually looks a bit colder than average over the next week, this corresponding to perhaps the only truly 'deep' cold air mass that exists on the Eurasian continent.

Not only has that got to travel a long way west, but it has to avoid interacting too much with an extremely above normal airmass in the far-eastern Mediterranean:

It's not often that you see a +20*C 850 hPa anomaly to start the spring in the mid-latitudes.

Current model output introduces a break to the the long-fetch easterly flow before it can achieve much, so that's where we'd need stronger, more sustained blocking to the N and NE of the UK before we could even consider such an import to be on the cards.

More likely we'll have to make do with trying to develop a cold pool closer to home. Achieving this over Scandinavia becomes increasingly difficult at quite a pace as March progresses, but up toward Svalbard and the surrounding sea ice, there is greater scope for developing a cold enough airmass to be able to deliver snow-supportive low level conditions provided the sea track is not too drawn out. Best path drops down through western Scandinavia and then west from there.  Results wouldn't be spectacular but there would probably be some snow to be had for most parts, though accumulations would struggle to occur in the south during the daytime.

So in terms of something for southern snow hunters to chase in the model output that is fairly reasonable in terms of the expectation, cold pool development around Svalbard (preferably 850's to around -14*C or below) followed by an import via a Greenland/Iceland ridge with LP over S UK (ideally SE) is the target in my opinion.

For northern snow hunters, Arctic maritime incursions from the NW/N, which are far less of an ask, will probably suffice to bring various spells of snow at times, some settling, particularly overnight and over high ground.

[Sideways Snow]

6 minutes ago, Singularity said:

Good spot Kyle, I continue to anticipate increased amplification which may serve to improve the draw-in of cold air later next week and beyond.

There are a great many on here who could do with shaking themselves clear of the idea that snow of any description is out of reach for southern UK this coming March. The bigger issue is getting any to settle or stick around during the daytime.

The best outcome exploits the boost to convective features that the stronger sun brings to produce an onslaught of heavy snow showers at a rate great enough to overcome the daytime thaw... a rare but beautiful beast (as you get to see the results in daylight for much longer at a time than in the depths of winter). With diving troughs into Europe and - potentially - some more significant cold air encroaching from the NE toward the end of the first week of March (compared to what we've seen through the majority of the winter), there has to be a chance for eastern parts in particular - but this is just a possibility at this stage so no need for anyone to get excited or panic.

In terms of 500 mb and surface pressure patterns, March 2016 may well be among the more spectacular of the past century, but for the air temperatures to follow suit across the UK and NW Europe (as in be spectacularly cold for the time of year), there would have to be an import from central parts of Asia where it actually looks a bit colder than average over the next week, this corresponding to perhaps the only truly 'deep' cold air mass that exists on the Eurasian continent.

Not only has that got to travel a long way west, but it has to avoid interacting too much with an extremely above normal airmass in the far-eastern Mediterranean:

It's not often that you see a +20*C 850 hPa anomaly to start the spring in the mid-latitudes.

Current model output introduces a break to the the long-fetch easterly flow before it can achieve much, so that's where we'd need stronger, more sustained blocking to the N and NE of the UK before we could even consider such an import to be on the cards.

More likely we'll have to make do with trying to develop a cold pool closer to home. Achieving this over Scandinavia becomes increasingly difficult at quite a pace as March progresses, but up toward Svalbard and the surrounding sea ice, there is greater scope for developing a cold enough airmass to be able to deliver snow-supportive low level conditions provided the sea track is not too drawn out. Best path drops down through western Scandinavia and then west from there.  Results wouldn't be spectacular but there would probably be some snow to be had for most parts, though accumulations would struggle to occur in the south during the daytime.

So in terms of something for southern snow hunters to chase in the model output that is fairly reasonable in terms of the expectation, cold pool development around Svalbard (preferably 850's to around -14*C or below) followed by an import via a Greenland/Iceland ridge with LP over S UK (ideally SE) is the target in my opinion.

For northern snow hunters, Arctic maritime incursions from the NW/N, which are far less of an ask, will probably suffice to bring various spells of snow at times, some settling, particularly overnight and over high ground.

Great post, much more informative on this fantastic model thread than the pointless petty argumentative posts that keep on popping up! 

[knocker]

After a wet Tuesday the GFS is still plugging some nasty weather at the end of next week and a transient snow event. Obviously some way off and subject to major changes, but it did get some support from last night's ecm so it will be interesting to see what the latter comes up with this morning. Worth keeping a beady on and could be looking at at a few cms in downtown Solihull.

Edited February 26, 2016 by knocker

[winterof79]

A sinking trough forecast for the end of next week eventually,drawing in an easterly/N/E feed.Hopefully better than this weekends effort

 

[chris55]

ECM 168 shows yet another slider at 168, not one of these has delivered anything wintry yet this winter, but if the ppn is heavy then charts like this are absolutely capable of delivering snow, even in March!

 

 

[Man With Beard]

The ECM completes its turnaround this morning, now becoming probably the most wintry model on offer for days 6-10, with a very rampable run for north of the M4. A trough gets stuck over southern Britain at T144/T168 and slowly edges south, with a weak ridge to the north bringing in another easterly. The last gasp snow chase continues, then.

[winterof79]

Something tells me there will be lots of cold opportunity through to at least middle of March.Check out the GEFS panel on meteoceil.Best set I've seen for a LONG time

Here is just one possible outcome and for once I could pick more to show.

[knocker]

The ecm is close but no cigar. More runs needed.

 

Edited February 26, 2016 by knocker

[Johnp]

1 minute ago, knocker said:

The ecm is close but no cigar. More runs needed.

 

Close to what?

[knocker]

6 minutes ago, Johnp said:

Close to what?

Close to the GFS but it disrupts just to the west and travels SE into Biscay and although this produces an easterly flow for a time it's not particularly cold as we have seen before. It's a tad academic at the moment anyway but interesting to keep an eye on.

Edited February 26, 2016 by knocker

[MR EXTREMES]

the midlands north could do well through coming few weeks anyone south or sw se of this would be very disappointed through the two or 3 week period going into march.

you can see the upper 850s being mixed out frequently even into Europe and northeastern Europe.

and a dressing cool march to come there is absolutely nothing extreme or remotely extreme in terms of cold typically this holding on to hope of something exciting into march for cold could very much provide utter disappointment after disappointment as we have endured through winter 15/16 I'm glad its over.

and I'm not retrieving the towel from the ring and to get excited about a vortex split is just to little to late as been stated vortex 3-0 that's 3 winters in a row for anything exciting we need weak vortex from the start of its formation we need sustained low solar minima lower than we have seen through the last 3 years something like 2008 long drawn spotless sun east QBO and then the southerly tracking jet stream all this has not been a feature in the last few winters.

 

gfs at 192 shows cold but not wintry unless on top of hills and especially mountains

ecm has possible wintry weather on the hills and mountains in the north and north east perhaps possible lower levels most of the uk cold but not the exciting type.

the 240 ecm although cold still hit and miss although favoured areas as before in the 192 ecm chart.

if colder and snowy is what your looking for then a straight arctic sourced air !

them deep purple negative 850s as shown on the ecm.

it would take that after such a mild winter to really establish a real wintry spell,

none of the directions of cold shown on the models are sustained flows with sustained deep purple upper air 850s.

I thought id give my explanation as I didn't want to disrupt the model thread.

but holding on to hope of an exceptional march would send the pharmaceutical industries order of Prozac to a record high.

all this said there will be some wintry weather at times mostly higher ground in the north.

[MR EXTREMES]

43 minutes ago, knocker said:

Close to the GFS but it disrupts just to the west and travels SE into Biscay and although this produces an easterly flow for a time it's not particularly cold as we have seen before. It's a tad academic at the moment anyway but interesting to keep an eye on.

very true knocker the 850s air getting higher and higher each run except for the extreme north in and around Greenland and the arctic any lower 850s that do filter into northern Europe and the uk look low but not sustained and most certainly not low enough to get the sledges out.

it would take an exceptional arctic sustained source of air to really be excited.

and that's just not likely this year as things stand.

[johnholmes]

All 3 anomaly charts I use are again similar after the hiccup from ECMWF yesterday, so 2 weeks perhaps longer of their upper air pattern, sorry not got time to post my usual links

 

[Gustywind]

Disappointed with the ECM 850s, very good looking charts later in the run which in a normal winter you'd expect would produce -8s relatively comfortably, possibly colder. Yet we struggle to even get to -6 nationwide, pathetic!

Shades of Feb05 for me when even more spectacular Synoptics produced equally poor results in terms of depth of cold.

Struggling still to see anything wintry south of the Pennines over the next couple of weeks, just more cold rain.