Model Output Discussion - Spring Has Sprung

[feb1991blizzard]

SNOW!

[Mike Poole]

GFS, GEM and UKMO all showing a trough dropping over the UK with cold air from the NW.  T144:

Certainly some interest in the north for snow, especially with elevation.

[Tim Bland]

Shane we didn’t get this a month ago…

[LetItSnow!]

 Tim Bland Very 19th century esque looking chart, after a very mild February then get walloped with cold charts in March 

[Tim Bland]

Dusting possible almost anywhere end of the week  but Especially northern hills 

[MJB]

 Tim Bland Shows we can get the right set up, just bloody timing eh

[Mike Poole]

 MJB For me, unfortunately, the evidence seems to increasingly suggest that we can no longer get the right set up, during the months that matter, or at least it is now extremely unlikely.  It is not a timing issue, March (and April) are different and winds from the north or east have always been a little more likely in spring than winter.  

It is the almost total absence of any snowy setups in the winter months during the last decade (since Jan 2013 actually) that is worrying.  

[WYorksWeather]

Definitely still a chance of something warmer and drier with the GFS continuing to show this sort of pattern around day 10.

The mean is still fairly equivocal - charts below from days 9, 11, 13 and 15:

The high does ridge into the south for a few days, but the pattern is fairly flat.

The GFS 12z OP shows something more at the upper end of possibilities. Here is the beginning of the transition to something drier around day 8:

By day 10, a strong UK high has set up, driving a flow from south of west across most of the UK:

By day 12, the mean flow turns easterly, which you would think would be still be cold, but not especially.

By day 15, the synoptic pattern doesn't look all that special - it's a straight southerly or slightly south of east.

However, temperatures under that pattern are fairly impressive for the time of year. Widespread mid teens, high teens in a few places. In reality, perhaps even an outside chance of the first 20C.

Summary

The GEFS ensemble still leaves a lot undecided, but it has to be emphasised that a spell of very mild or possibly even warm weather is a possibility as we move into the second week of March. At the moment, the 12z GFS is solution is at the very top of the ensemble in deep FI, so without more support I'd probably expect a more mixed scenario to be where we end up, perhaps low to mid teens with some cloud and showers rather than properly warm and dry.

You can see this on the GEFS temperature ensembles, which are clearly a mixed bag. A slight warming trend evident into March, but something notably warm remains a minority option.

 

[Theresnoway]

 Mike Poole There was a period down south between roughly 2000 and 2010 where we had hardly any snow, then came along 2010, 2013 and 2018. So although we won’t get favourable conditions every year, I still believe the right synoptics will come around eventually, even given longer term changes in climate.

[RJBingham]

 WYorksWeather  Yes, always been a big fan of the GFS 

 

Edited February 24 by RJBingham

[WYorksWeather]

Nice to see the ECM also getting on the high pressure train, but taking a little longer to get there, around day 10 perhaps. GFS on the right for comparison.

Huge amounts difference elsewhere so the future development is unlikely to be the same, but good that both model runs get there.

Need to wait for the ECM ensembles though to see if there's any shift there, so not much point commenting further until later on.

[Beanz]

 WYorksWeather looking like the perfect start to a spring season - what’s not to like about those ensembles! 

[Tim Bland]

From an IMBY point of view I’d bank the 18z …That’s 9cm more than I’ve seen so far this winter 

Edited February 24 by Tim Bland

[Metwatch]

[Rain All Night]

8 hours ago, Rain All Night said:

0z/6z deterministic runs, Sat 24th to Sat 2nd (day 7)

Am I to be encouraged by the amplification, or concerned that the trough at the turn of the month may be getting trapped over the UK?

0z/6z ensemble means, Sat 24th to Sun 10th (day 15)

This morning's means start to diverge quite early (2nd Mar, day 7) as the little trough drops over the UK. ECM, which not quite as impressive as yesterday's 12z, still offers hope of high pressure subsequently in a protective role for the UK, as does the GEFS.

12z/18z deterministic runs, Sun 25th to Sat 2nd (day 7)

12z ensemble means, Sun 25th to Sun 10th (day 15)

The point at which this next trough drops over the UK, which is now crossing into "week 1", and which by now feels like we've known it's coming for an age, really does seem to be quite a fork in the road for the models; it remains completely unclear what will follow this event. Heights to the east and mild air flows from south of west remain modestly signalled.

It still seems there will be a moving of the furniture upstairs in the stratosphere throughout the first week of March. Whether or not this has anything to do with the model uncertainty beginning at around the same time is above my pay grade.

Edited February 24 by Rain All Night

[Dennis]

good sunday to all

[carinthian]

Morning all. Thursday will see a active front move across The British Isles with more rain again. All models end the week on a cold note with snow possible for quite a few from Friday as a wedge of cold air sinks over the British Isles. Typical ,first day of the Spring month ! Any snow wasted at low level but better than mild mush after such a long wait.

C

[TillyS]

Good morning.

All 3 models now have a Scandinavian High signal at around the D7 point.

Unfortunately that still isn’t reliable timeframe but it’s an interesting development. And for me personally it would be a big bonus as I’m off to Norway on Thursday for 11 nights in search of snow and northern lights.

Curiously this still isn’t yet really leading to UK cold. Here’s an example:

 

[Duane S.]

It does now very much look like there will be a proper reversal up above. One would imagine that would not be without consequence going through March, giving a cold March. An increased probability of anyway.

But after this winter

[Cambrian]

A slow pattern as we enter meteorological spring, as low heights on the western side of the Arctic vie with positive heights on the eastern side - the tropospheric PV, that never really got going this winter, withdrawn to northeast Canada, but extending a cold trough through Greenland and Iceland, down into the UK and Ireland, here at day 5 on the 0z GEFS. 

 

There is a decent Atlantic ridge, and as this topples, it links up with heights over NE Europe and western Russia at day 7, allowing for development of a cut-off low over the UK and Ireland, maintaining its own pool of cold air, in this evolution, likely this year for meteorological spring to kick off with a distinctly chilly feel, mean T850s at day 6. 

 

Thereafter, another trough drops through Greenland by day 10, this time to the west of us over the Atlantic. This looks to be followed by another bisection of the trough, forming another cut-off at the base, which again slowly migrates southeast over Western Europe by day 15. 

  

A big difference at this stage though, is that the PV has moved northeast over the pole, all the troughing is removed from Greenland, allowing heights to build through the North Atlantic to Scandinavia, the pattern by then looking to be even slower, very typical of recent springs with a slow, chilly start to the season. Have a great day. 

[Anthony Burden]

Morning all,as I mentioned before it’s looking like spring could be on hold for sometime the charts showing a day or so mildish the rest on the cold side with even some snow for some.With the polar vortex well and truly shredded and a solid wind reversal the effects of this could be substantial for northern blocking within 10 days or so,March CET temperatures will be very interesting I think this site will be very active this March for cold lovers.

 

[RJBingham]

Nothing cold on offer from the big two.

[ANYWEATHER]

Still ,looking for a dry period. Ecm ,slows down the relentless assult of the Atlantic by day ten, gfs has been showing it ,but todays output as changed.  Nevertheless, something drier and hopefully warmer on the horizon as we step into Spring in a few days time....☺

[Mike Poole]

Just looking at the uncertainty on the cold plunge next week, T144.  The ECM clusters have 5 scenarios:

Looking at the representative members at T144, the 580 hPa temperatures are as follows (in order for clusters 1-5):

Clusters 1 to 4 have low pressure over the UK.  Cluster 5, although cold might well be dry.   Cluster 2 looks like it will be cold enough for snow in many places, cluster 3 also locally pretty cold, cluster 1 marginal, cluster 4 very marginal.

[Met4Cast]

My focus is primarily on the stratosphere at the moment & potential impacts from a major SSW during early March. Still not much urgency to downwell the -ve anomalies quickly, modelling now goes out to the 10th March.

Strongly -NAM state despite this though but with little blocking to speak of in the troposphere. We've seen quite an abrupt change in MJO forecasts in recent days too, initially looking like a return to phase 5 has now switched to returning to phase 3/4 in the Indian Ocean following the previous decayed signal. Phase 3/4 composites for March are very unsettled for the UK, phase 3 perhaps a little chillier.

In essence though - For those still chasing cold/snowier outcomes, I think it might almost be time to give up the ghost.