Model Output Discussion - A cold start to Spring?

[Winter Hill]

Just now, Tim Bland said:

My analysis is based on needing less than sub -5 hpa for proper snow, -8c or lower for at this time of year 

Large areas of northern England are still under cold air. In the chart you posted 

 

so it’s beyond me why you stated it’s game over for entire England??

[Tim Bland]

Just now, Man With Beard said:

In 2018, we had snow on the south coast all the way to 0C 850hpa.

We may not have the same depth of cold this time, but the same principle applies, easterly draw before a front, 850s can be higher than usual.

Fair enough, as you say if dp / dam is low enough. I was looking at it as a warm front moving up from the south 

[EML Network]

10 minutes ago, Mike Poole said:

GFS, UKMO and GEM at T96:

Looking through the runs, I think GFS has the most propensity to string out the incoming lows, making them weaker affairs.  I think we are now in the timeframe where we might see a southern correction as we approach T0 on the first half of next week.  It is difficult to call, partly because the wider hemispheric pattern is quite unusual.  

It is likely there will be a warm up for the southern half of the country towards the end of the week, but the cold may push back quite quickly, but that is so for another day!

I’m not really sure what most were expecting with this chase.  For me, given the late season, it was as much about an opportunity to learn from another SSW event, they don’t happen very often; as it was about snow potential.  But once we saw the wholesale migration of the trop PV in response to the SSW, I think most could be forgiven for setting expectations higher than what it seems is to be delivered.  Ho hum!  

Although I think the colder than average weather will persist into mid April, I suspect that in two weeks the chance of any meaningful snow will be over, at least for the south, so it is what it is, hope everyone manages to see at least some snow over the next few days.

UK winters really are a joke.  Second winter running without seeing a single snowflake.  Last time was end of November 2021 and that doesn’t qualify as winter, and, to be fair, nor will next week!

wow not often you see such differences in the models a mere 4 days away.

About the only similarity is that it will probably be cloudy and dry for most

[Mike Poole]

How far south might the deep cold be T60, here are P9 and P17:

That’s quite astonishing at that range!

[Man With Beard]

Just now, Mike Poole said:

How far south might the deep cold be T60, here are P9 and P17:

That’s quite astonishing at that range!

Mike there's nothing like the Atlantic running into an NE flow to cause absolute chaos, is there! 

Where is FI right now? T24? T36?

[Mike Poole]

Just now, Man With Beard said:

Mike there's nothing like the Atlantic running into an NE flow to cause absolute chaos, is there! 

Where is FI right now? T24? T36?

I think it is at the point where it isn’t worth using models to try and predict!  

The early part of next week is a radar and nowcast job!

[Rossmcfc]

I think it'll surprise a few people with the snow, still think M4 South will be a good area Tuesday and Wednesday. Beyond that Midlands North looks good

[Spikey M]

12 minutes ago, PiscesStar said:

So, being in Herne Bay, Kent... Are we still in the snow zone at this stage? 

At this point the models aren't sure if you'll need a snow shovel or an umbrella. It looks wet, but it's too marginal to call.

Edited March 5, 2023 by Spikey M

[Tim Bland]

Latest UKV has snow in central areas Thursday transitioning north and turning to rain. By Friday the snow line has cleared into Scotland (away from high ground ) 

[Guest]

9 minutes ago, Man With Beard said:

In March 2018, we had snow on the south coast all the way to 0C 850hpa.

We may not have the same depth of cold this time, but the same principle applies, easterly draw before a front, 850s can be higher than usual.

Well that’s not quite 100% what happened here, there was a very pronounced thermal gradient right over the coast at the 850 level. As the milder uppers overlaid the surface easterly the snow quickly turned into a lengthy spell of freezing rain with the cold layer staying below freezing. 0C 850pha air is not conducive for snow, only the easterly undercut in March 18 stopped rain washing the snow away quickly. 

[Lampostwatcher]

2 minutes ago, Tim Bland said:

Latest UKV has snow in central areas Thursday transitioning north and turning to rain. By Friday the snow line has cleared into Scotland (away from high ground ) 

What's its showing for Tuesday?

[Tim Bland]

1 minute ago, Lampostwatcher said:

What's its showing for Tuesday?

Band of sleet &snow cleared south in the morning followed by showers mainly east 

[Lampostwatcher]

1 minute ago, Tim Bland said:

Band of sleet &snow cleared south in the morning followed by showers mainly east 

You would think it will be cold enough for all snow 

As it snow this morning here

[ItNeverSnowsInWindsor]

1 minute ago, Tim Bland said:

Band of sleet &snow cleared south in the morning followed by showers mainly east 

Looks good for the Chilterns and the North Downs. 

[Tim Bland]

I always find the UKV underplays snow risk when it come to precip type  so I wouldn’t worry. Will almost definitely fall as snow almost everywhere from Tuesday but whether it will settle is anyone’s guess at this stage 

[Cambrian]

12z GFS op for day 10 looks like a proper Dumbo when compared with the ensemble mean 

  

Uppers not bad in either though.

 

Doesn’t look like this mild spell is gonna fly.

[Jamie M]

28 minutes ago, PiscesStar said:

So, being in Herne Bay, Kent... Are we still in the snow zone at this stage? 

As another Herne Bay resident, I'd say the 850 hPa temps might be a bit too marginal for here aye. 

[Rain All Night]

34 minutes ago, PiscesStar said:

So, being in Herne Bay, Kent... Are we still in the snow zone at this stage? 

Is that a UKV chart at +150 hours? I thought that model only went out to +120 hours..?

[BlackburnChris]

28 minutes ago, Man With Beard said:

Mike there's nothing like the Atlantic running into an NE flow to cause absolute chaos, is there! 

Where is FI right now? T24? T36?

T-6 I think lol , Gfs has this band of Snow tomorrow night being widespread , but i'm not even convinced that will happen ... 

 

[alexisj9]

Just now, BlackburnChris said:

T-6 I think lol , Gfs has this band of Snow tomorrow night being widespread , but i'm not even convinced that will happen ... 

 

It's on arpege high Res too. But still might not happen.

[Mark wheeler]

1 minute ago, alexisj9 said:

It's on arpege high Res too. But still might not happen.

Aprege has it earlier on Monday evening and is all rain .  Maybe I am looking at a lower resolution model though.

[Stuie]

1 minute ago, Mark wheeler said:

Aprege has it earlier on Monday evening and is all rain .  Maybe I am looking at a lower resolution model though.

That`s only 5pm Mark, it`s the overnight that is the interest. 

[BlackburnChris]

Aprege has another band behind it but , it does't do a lot with it and breaks it up as it moves South ...

 

[Mark wheeler]

3 minutes ago, Stuie said:

That`s only 5pm Mark, it`s the overnight that is the interest. 

Thanks, however I am still not seeing any precipitation then ?

[Stuie]

Just now, Mark wheeler said:

Thanks, however I am still not seeing any precipitation then ?

It`s still a big Q, LP in the North sea is key.