Model Output Discussion - Snow Watch limited edition

[Polar Maritime]

Snow has already turned to rain here at my location.

[geordiekev]

20 minutes ago, minus10 said:

You'd think from here there would be some kind of easterly..

..but no...the gfs 12z doesnt make it..

we end up with this at t300

...after cold dip gfs seems all over the place from run to run at present...to be expected i suppose..however still signal for trough disruption and heights blocking in all these variations...

 

Yeah GFS been flipping between Greeny & Scandy heights towards back end. Defo seen worse, period around the 20th I guess is the crunch point 

[geordiekev]

1 minute ago, Polar Maritime said:

Snow has already turned to rain here at my location.

Yeah, think I'm only forecast about 2hrs worth just East of N Pennines, before the rain follows then ice threat

[Cambrian]

Briefly milder for all with a southwesterly flow during Sunday and Monday as low pressures tracks across the north, before winds turn northwesterly bringing some properly cold air south again. 

  

12z GFS operational run through to Tuesday night offers further falling snow for more or less all of the UK and Ireland and fresh coverings for many. 

  

Interleaved with milder interludes, our wintry March continues - look out Cornwall ! 

[Stuie]

16 minutes ago, Polar Maritime said:

Snow has already turned to rain here at my location.

this front is early, was supposed to be around 10ish (there is the model lag). you do have heavier precip coming so see if you pick up again.

This hasn`t been modelled by the op`s very well, went against the jet stream. Anyway I have something imminent here, will report. DP is -2.4.

I do use the NW radar btw!

Edited March 11, 2023 by Stuie

[Polar Maritime]

11 minutes ago, Stuie said:

this front is early, was supposed to be around 10ish (there is the model lag). you do have heavier precip coming so see if you pick up again.

This hasn`t been modelled by the op`s very well, went against the jet stream. Anyway I have something imminent here, will report. DP is -2.4.

I do use the NW radar btw!

Back to snow now! As you say heavier precipitation on the way.

Edit- Moderate snow now

Edited March 11, 2023 by Polar Maritime

[Stuie]

You can see where Tuesdays headache comes from.

[alexisj9]

1 hour ago, minus10 said:

You'd think from here there would be some kind of easterly..

..but no...the gfs 12z doesnt make it..

we end up with this at t300

...after cold dip gfs seems all over the place from run to run at present...to be expected i suppose..however still signal for trough disruption and heights blocking in all these variations...

 

More dry high pressure. We'll at least it's at 300, while a long time before then still seems to be up in the air at the moment.

[Stuie]

42 minutes ago, Stuie said:

this front is early, was supposed to be around 10ish (there is the model lag). you do have heavier precip coming so see if you pick up again.

This hasn`t been modelled by the op`s very well, went against the jet stream. Anyway I have something imminent here, will report. DP is -2.4.

I do use the NW radar btw!

No snow/sleet/graupel/rain - have to wait for the next showers. 

Cambs Uni data.

[Stuie]

56 minutes ago, Cambrian said:

Briefly milder for all with a southwesterly flow during Sunday and Monday as low pressures tracks across the north, before winds turn northwesterly bringing some properly cold air south again. 

  

12z GFS operational run through to Tuesday night offers further falling snow for more or less all of the UK and Ireland and fresh coverings for many. 

  

Interleaved with milder interludes, our wintry March continues - look out Cornwall ! 

Kind of think the SW flow will be flatter after today. The flow was almost predicted as a ridge over the UK but the Iberian HP looks a little suppressed.  

6z`s may confirm.

Edit: If this real time data from NCEP is correct, look at the flow off the Iberian HP.

Edited March 11, 2023 by Stuie

[Stuie]

FAX charts have been a little `iffy` recently so take these with a pinch. Chasing an event South of North Wales on Tuesday looks like wasted energy from todays run.

Note the 528 DAM

Monday                                                      Tuesday

     

The front from the North isn`t a cold front, it`s occluded also.

The 2nd FAX is ahead of the precipitation but even then the 528 DAM only gets to N Wales/Midlands.

The LP`s are pretty nailed on still to come in, it just doesn`t look cold enough for an `event`.

[Stuie]

27 minutes ago, Stuie said:

Kind of think the SW flow will be flatter after today. The flow was almost predicted as a ridge over the UK but the Iberian HP looks a little suppressed.  

6z`s may confirm.

Edit: If this real time data from NCEP is correct, look at the flow off the Iberian HP.

12z ECM has 2M highs for tomorrow less than the predicted 12Degs in England at lunch. 

 

[Stuie]

Tomorrows 2M temps with both the GEFS and the ECM ensembles. Hitting 12 degs looks off the cards.

 

If Mondays temps are diluted tomorrow then maybe Tuesday has some legs. (big ish)

EDIT: Jet could favour the East coast if temps calm down. 

Who gives a DAM

Edited March 11, 2023 by Stuie

[Frosty.]

The GEFS 12z mean looks more benign in late March?!.. dare I say, more spring like?…  .hey, let’s look forward to spring proper now!..winter was mostly a sham!..let’s hope for a decent spring  which evolves into a great summer…   

Edited March 11, 2023 by Frosty.

[Sunny76]

On 10/03/2023 at 10:09, SussexSnowman said:

Loving the pictures. Whilst it might not be winter, it’s safe to assume that everyone over the last few months has had a dose of snow

Who doesn’t love dog related snow videos. Here’s mine from December when we got the white stuff. My Westie just loves it! She may be getting on in years and hampered by arthritis, she’s still young at heart and I hope she has more snow days left.

 

Yeah, even we had a light covering of snow during a Sunday evening in mid December and the streets were covered in ice for several days. 
 

The snow has been poor in my location, but I will remember winter 2022/23 for being cold dry and sunny at times, with a few weeks of mild damp weather thrown in. The cold has been more frequent this time round.

The december spell was definitely the coldest for many years. I think it was the coldest December overall since 2010, and the only other Decembers to match in terms of cold days were probably 2017(first half) and 2020(second half and Christmas period).

[alexisj9]

4 hours ago, Stuie said:

12z ECM has 2M highs for tomorrow less than the predicted 12Degs in England at lunch. 

 

Thought it might be.

[minus10]

18z pub run reminding us that cold can still be a player later this month..(JFF)...

o

...bit of a northerly there...all change of course next run..

 

[geordiekev]

45 minutes ago, minus10 said:

18z pub run reminding us that cold can still be a player later this month..(JFF)...

o

...bit of a northerly there...all change of course next run..

 

Not much stopping an almost cross polar flow, although we know it's eye candy for now

[Weather-history]

UKMO 0z shows a period of gusty winds coming behind the front Monday/Tuesday night for Northern Ireland, Irish Sea (North Wales), Yorkshire coast and into the North Sea

[IDO]

There is no change from two days ago, cold slack zonal for the next eight days or so, and no strong narrative from then. The GEFS highlight this:

The GFS op, supported by the control, as it does, follows the colder cluster. The op and control look reasonable in synoptic, that slack flow, allowing wedges of heights to a higher latitude, so a quasi-blocking pattern post-D8 is an option. The GEM op has moved to this take:

Wedges, if just wedges, could mean something or nothing for the UK. But I remain unconvinced the upcoming NH pattern is SSW related; if it is, then it is a rather tame affair. ECM D9:

[BlueHedgehog074]

A little peak at the models for Tuesday mid day this week, they set free a chilly North-Westerly over the UK. This of which dragging some pretty cold 850 hPa temperatures and low heights and thicknesses (via the UK/Western Scandinavian trough) further South/South-East:

06Z GFS

0Z ECMWF

0Z UKMO

 

0Z GEM

06Z ICON

Still could bring some blowy weather, particularly early on into Tuesday,

 

Isobars quite tight over the UK above. A chance for this to bring some squally wintry showers and some squally areas of rain, sleet and snow as Monday’s Low escapes into the North Sea. 

Some models above, such as the UKMO and ECMWF, look a touch flatter with the North-Westerly for Tuesday, particularly towards the Southern part of the UK.

Seems to depend really as to the speed that Atlantic/Azores ridge builds in from the South-West and how it tries to dislodge the North-Westerly flow into, and through, Wednesday. The -5*C 850 hPa temperature line struggles to get to the far South-West of the UK on the ECMWF which could make showers less wintry, except perhaps over the hills, such as those in Dartmoor. 

The GFS and GEM perhaps the most amplified with the North-Westerly on Tuesday, but overall when looking at the above charts there’s not much give or take to it. It could be fair to say GFS is the most ambitious with how far South it floods those cold 850 hPa temperatures reaching Northern France! (The GFS, however, can be prone I feel to overdoing the cold depth of the 850 hPa temperatures a little). 

Having said that, it looks to be a day of wintry showers for places, particularly over North-Western areas and over high ground to the North and West. Some are likely to stream South-East through the Cheshire Gap ganging up on the Midlands too - especially Northern parts of the Midlands from the charts above that show more of a West-North-Westerly flow over the Southern/Central parts of the UK.

With the strengthening March sunshine, some could pop up inland, plus with the heights being low, especially further North over the UK, some of these wintry showers are likely to be beefy. These bringing snow across the hills, and to lower levels at times too, particularly Midlands Northwards, although I expect there to be some sleet, hail and graupel showers in the mix as well. 

While it looks to be a cold and, at times, blustery day, where the sun shines between the showers it could feel fairly pleasant. Some places, perhaps more so down the fairly far South, may miss a lot of the showers. It is also worth saying that with many of the operational models above showing some kinks and little troughs in the flow, there could be a chance of more organised wintry showers and longer spells of sleet and snow sinking South through parts of the UK during Tuesday.

It may not be a Northerly/North-Westerly flow of -10*C hPa temperatures (with far North-West of Scotland maybe having a chance to get into the -10*C’s briefly), but that day does provide a chance for a return of wintry weather. For a North-Westerly, it looks to be a rather potent one. One that could bring a good amount of interest. As well as some of the strong winds it’s likely to bring earlier on in the day. 

[feb1991blizzard]

GEFS building a solid (not spectacular- yet) ridge - Atlantic / S Greenland, can't take it seriously yet as EPS not interested / much less aggressive - chalk and cheese.

[Allseasons-Si]

8 minutes ago, feb1991blizzard said:

GEFS building a solid (not spectacular- yet) ridge - Atlantic / S Greenland, can't take it seriously yet as EPS not interested / much less aggressive - chalk and cheese.

Yes you beat me to it Feb

06z vs 00z at day ten...

and there is quite a cluster below the -5 line,...let's see how we progress with this and as you say,...the EPS need to be of the same page.

 

Edited March 12, 2023 by Allseasons-si
Added chart

[feb1991blizzard]

Here's what we're looking for this time of year, troughs imbedded in an Arctic airmass.

[Mike Poole]

There is another cold plunge into the middle of next week, GFS has cold air in place T66:

Snow chances.  Well the ARPEGE ensembles have this for the probability of snow for the next few days:

Some chances there for Scotland and the north, but very little for the midlands south.