Model Output Discussion - A cold start to Spring?

[rug]

1 minute ago, Man With Beard said:

GFS 12Z has the channel low 5mb deeper for Wednesday and as a result parts of Dorset/Devon/Wiltshire would wake up to a real hammering of snow.

“Wake up” I’ll not be going to bed….

[SLEETY]

Amazing how we get high pressure in  the correct place for cold weather when suddenly the Atlantic wakes up and low pressure after low pressure pushes through the UK .

Where were the low pressure systems when we had that very mild and dry Feb.

Never understand the UK climate,in regards getting cold weather to last more than a day or two.

[weirpig]

Aromes take on were the snow will fall.    gives you a good idea of the low on wednesday morning.

[kold weather]

I've not seen the earlier part of the UKMO run for the Tues-Thurs period. What I will say for the moment is the 12z suite the UKMO is pretty much at the extreme end, the ICON is closest to it but is still a solid 5mbs weaker.

For now I'd not worry too much what the UKMO is showing, it is showing the option at one extreme of the spectrum that has minimal support even out of all model ensembles from earlier in the day. Worth a watching brief, but nothing more than that.

So far the trend from the 12z is to slightly move Tues-Weds frontal system northwards compared to the 12z suite yesterday. some are now looking legitimately snowy (5-10cms for the far south) others are more of a glancing blow, but still eonugh for several cms on most.

Beyond that, as mentioned earlier its a tricky forecast, maybe another wave comes through the south on Weds-Thurs followed by another event further north before the big push of milder air comes in Fri and another possibly more major events.

[Snowy L]

Looks like GFS is going for bowling ball too. Oddly the low disrupts during Wednesday but then regains shape in time to blast England with rain? Would say it's nonsensical but anything that keeps snow away from England seems to always make perfect sense in recent years.

 

 

I've never known such terrible luck and timing until this winter. So much promise yet easily the most frustrating winter I've lived through. ICON, UKMO and GFS all singing from the same hymnsheet and we are running out of time to reverse it unfortunately.

Edited March 6, 2023 by Snowy L

[Guest]

GFS 12z also going for more of a rounded low for Thursday now:

[mountain shadow]

I expect a major downgrade on those Met Office warnings if this system on Thursday continues further North and doesn't sharpen up. A very brief spell of snow and then back to rain.

[kold weather]

3 minutes ago, Snowy L said:

Looks like GFS is going for bowling ball too. Oddly the low disrupts during Wednesday but then regains shape in time to blast England with rain? Would say it's nonsensical but anything that keeps snow away from England seems to always make perfect sense in recent years.

 

 

I've never known such terrible luck and timing until this winter. So much promise yet easily the most frustrating winter I've lived through.

Looks like a snow-rain type event for northern England, could be a decent amount before it shifts.

Anyways at this point I'd not be overly worried, they are still frankly struggling to get Wednesday's system in the south nailed down, so I'd not be getting too laser focused on what different models/suites are showing for Friday yet.

And this is coming from someone who has no skin in the game later this week as its probably going to be too mild down here by then no matter what shape the low takes.

[Lampostwatcher]

Gfs 12z upgrade for the south for weds 

With parts north of the m4 into game

[kold weather]

2 minutes ago, mountain shadow said:

I expect a major downgrade on those Met Office warnings if this system on Thursday continues further North and doesn't sharpen up. A very brief spell of snow and then back to rain.

Still quite a significant snow signal on the 12z GFS, it is more rounded than previous runs so it may well shift to rain after a time, but GFS has quite a wide area of 8-12cms across N.England, S.Scotland and N.Ireland still.

[Updated_Weather]

Be interesting to see the ensembles.
& the control.

I do wonder how many rather take that low further south.

[MJB]

13 minutes ago, Man With Beard said:

GFS 12Z has the channel low 5mb deeper for Wednesday and as a result parts of Dorset/Devon/Wiltshire would wake up to a real hammering of snow.

M4 South do very well Breakfast time on Wednesday

[throwoff]

12z is upgrades for the south, now looking like tonight is out of play but Weds the low is in the perfect spot to hit most of the south of the UK

[weirpig]

Difficult to tell exactly where the line is  but the Alaro  goes full boss mode and places the low slightly further North on Wednesday   with some very heavy echos approaching the capital.

Edited March 6, 2023 by weirpig

[MJB]

Snap Shot of snowfall curtesy of GFS 12z 

Breakfast time Thursday snow into the West 

Lunchtime Thursday snow moves into parts of the Midlands and the NW ( incl NI )

Big snow event N Wales Northwards 

Early hours Friday N England S Scotland get a hammering 

Breakfast time Friday - N Britain under snow 

Saturday morning a wintry mix over England and Wales 

 

 

[nick sussex]

The UKMO is a bit flatter than this mornings run but still a bit surprising to see the models pumping up that low after the ECM 06 hrs run made it a shallower system .

[Bricriu]

8 minutes ago, mountain shadow said:

I expect a major downgrade on those Met Office warnings if this system on Thursday continues further North and doesn't sharpen up. A very brief spell of snow and then back to i

It still looks good for Northern Ireland, but not further south. I think catacol will be right there wont be settling snow for long except maybe for the very North of England and Scotland. At this stage  i would just be happy to see dinner plate size snow falling for a while.

[Tim Bland]

GEM looks good, especially for the weekend 

[kold weather]

6 minutes ago, Bricriu said:

It still looks good for Northern Ireland, but not further south. I think catacol will be right there wont be settling snow for long except maybe for the very North of England and Scotland. At this stage  i would just be happy to see dinner plate size snow falling for a while.

For the far south we have now decent agreement for a snow event on overnight Tuesday, the 12z GFS ensembles have near total agreement on the front being far enough north, a few actually end up drawing slightly milder air into the far south turning it back to rain for a brief time, though that is still a fairly small risk at this stage.

[Jarrow Posh]

GFS going for a 24 hour snow event for the far north of England and Southern/Central Scotland from Thurs into Fri.

[Mucka]

It is starting to look like a bit of a damp squib for much England based on today's output but still some snow around though perhaps not settling low ground with rain and sleet in the mix.

That said there is still hope for a correction back S which would give somewhere the chance of good dumping of snow before the mild air wins out.

Most at risk are central parts tonight and the SE Tuesday morning. The far South my see some snow Wednesday morning while the N  most likely Thursday night.

All of these events though have the risk of rain sleet being involved.

However UKMO and ECM have trended more toward snow being reserved for the far N and Scotland in the breakdown attempts from Thursday although there may still be snow before then for some.

UKMO actually has low pressure tracking NE toward Iceland instead of disrupting across the UK next weekend and it has firmly slammed the door shut on this mornings GFS 00z idea of maintaining the battleground across the UK with cold air fighting back S after each Atlantic incursion.

This mornings ECM, while poor, did at least put up a little resistance.

Regardless of differences in the output all the models have moved away from the deep cold pushing past the S and W coast and low pressure being forces S as it it attempts move in from the W with the jet firing up and returning N to cross the UK.

This was outlined as a possibility in the teleconnections but the hope was that the increase in Westerlies would not be enough to break down the cold pattern and we were scuppered by the Greenland high losing its influence more rapidly than expected,

Those same background signals give potential for a return to cold and blocking from around mid month although it will need to more fierce than the rather tame effort we have seen to bring worthwhile snow to lowland areas, especially since the sun grows ever stronger.

If we are to see a better prospect of decent snow from Atlantic lows for England then we need to see changes in the positive tomorrow and move the snow line back S I feel otherwise could be heading for UKMO type washout.

 

 

[snowking]

Awaiting the 15z UKV, but should be noted that the 12z UKMO-GM is significantly further South with the precipitation for Wednesday (to the point it misses the UK overnight) and is not much interested in much in the way of snow tomorrow morning. We're approaching the point where radar watching becomes more useful than model watching.

12z UKV vs 12z UKMO-GM for comparison

[Bricriu]

3 minutes ago, kold weather said:

For the far south we have now decent agreement for a snow event on overnight Tuesday, the 12z GFS ensembles have near total agreement on the front being far enough north, a few actually end up drawing slightly milder air into the far south turning it back to rain for a brief time, though that is still a fairly small risk at this stage.

Sorry, my post was a bit imby, yeah it looks good for the very south of England on Tuesday. Going off the GFS The Thursday to Friday event looks like a repeat of 22 March 2013, Northern Ireland and Northern England gets plastered while the rest of us get rain, or a brief snow to rain event. 

[Jacob Gamer]

30 minutes ago, Updated_Weather said:

Be interesting to see the ensembles.
& the control.

I do wonder how many rather take that low further south.

I would love that! Means snow for the south?

[kold weather]

1 minute ago, snowking said:

Awaiting the 15z UKV, but should be noted that the 12z UKMO-GM is significantly further South with the precipitation for Wednesday (to the point it misses the UK overnight) and is not much interested in much in the way of snow tomorrow morning. We're approaching the point where radar watching becomes more useful than model watching.

12z UKV vs 12z UKMO-GM for comparison

It is worth noting that the UKMO is by far the most far south of any models on the 12z suite this far, and I've not seen a single member of the GFS ensemble be that far south on the 12z suite either. Probably one for the bin.

With that being said, it does bring in another strong pulse into the south on Thursday instead.