Model Output Discussion - A cold start to Spring?

[bryan629]

9 minutes ago, Harsh Climate said:

Peach of a run for northern england, this is what I was talking about yesterday. Could be a case of the same places getting hit over and over again from systems tracking east into the cold air.

Agreed!! Total whiteout for northern England on this run, but with model volatility as it is probably all gone next run 

[Man With Beard]

UKMO 12Z - close to where the lines bend, there's a chance of snow - Tuesday, Wednesday and Thursday

 

[Scott Ingham]

Id say the northern boundary will be Leeds and southern boundary Cambridge East and West as it stands taking into account southern corrections. Id like to live in the midlands. Somewhere like Birmingham could well be the sweet spot. (This is all guesswork however based on nothing scientific other than past experiences of these systems)

Edited March 5, 2023 by Scott Ingham

[Mark wheeler]

Harmonie with a sleet / snow event moving south through midlands and south/ south east Tuesday morning.

Edited March 5, 2023 by Mark wheeler

[tight isobar]

The usual deciphering syncs apply!.. regarding possible white - to wet precipitation!.. And also the usual applies to marginal/ overhead fruition! The game could change largely ona geopgraphical point scale over nxt 24 hrs!! .. to me Barry .. to you paul!!?!! 

[Drifter]

6 minutes ago, Mark wheeler said:

Harmonie with a sleet / snow event moving south through midlands and south/ south east Monday morning.

*Tuesday morning.

[minus10]

This is becoming a real battle royal with the opposing warm and cold air forces at play..must be one of the toughest scenarios in meteorology to try and forecast..

...with the smallest of variations in the position of highs/lows, air temps, thicknesses etc can have massive differences on the ground...literally within 20 miles as to whether rain or snow..

...what is also very noticeable is the position and movement of the vortex , displaced to the east and moving south as well as can be seen in the gfs run..i think the pressure of that vortex is perhaps something the models are struggling to decifer and under estimate as it is outside their comfort zone...if there is such a thing..so no let up in the changes and movements with this battle...oh and mjo/ssw...yes well..i get the impression this battle will go right to the wire...then beyond it..

[Snowman.]

FI is pretty close, worrying about 120 almost seems pointless, but it the model discussion thread so anyone is free to talk about whatever time they please.

Still not convinced by any output shown.

[Mark wheeler]

6 minutes ago, Drifter said:

*Tuesday morning.

Sorry meant Tuesday , I knew Tuesday , god knows why I typed Monday .  Original post amended .

Edited March 5, 2023 by Mark wheeler

[Man With Beard]

UKMO also has snow potential tomorrow night, not a huge amount but there all the same

[Stuie]

Wednesday morning, wet bulb level is zero. Depending on the front coming from the North (position of LP to the East and what`s left in the tank), anything will be snow.

[geordiekev]

Just now, minus10 said:

This is becoming a real battle royal with the opposing warm and cold air forces at play..must be one of the toughest scenarios in meteorology to try and forecast..

...with the smallest of variations in the position of highs/lows, air temps, thicknesses etc can have massive differences on the ground...literally within 20 miles as to whether rain or snow..

...what is also very noticeable is the position and movement of the vortex , displaced to the east and moving south as well as can be seen in the gfs run..i think the pressure of that vortex is perhaps something the models are struggling to decifer and under estimate as it is outside their comfort zone...if there is such a thing..so no let up in the changes and movements with this battle...oh and mjo/ssw...yes well..i get the impression this battle will go right to the wire...then beyond it..

Yep the flow of cold from the trop PV to our NEast being pulled out into the Atlantic & then doing a U-turn and heading back towards us, is something I doubt the programmers have had to deal with much.

Disturbances in that flow back & forth have resulted in elongated systems earlier in the week, to more bowling ball of recent then both seperation and absorption of systems.

A real head scratcher for forecasters

[TEITS]

3 minutes ago, Snowman. said:

FI is pretty close, worrying about 120 almost seems pointless, but it the model discussion thread so anyone is free to talk about whatever time they please.

Still not convinced by any output shown.

Only output im confident of is the possible snow moving S during Monday night/Tues. 

Apart from this the difference in the 0Z & 12Z UKMO is making me think its pointless looking beyond Tues. A special mention to our members in Scotland though is the chances of remaining cold throughout is looking more likely than I previously thought,

I shall take this though.

[snowsummer]

29 minutes ago, bryan629 said:

Agreed!! Total whiteout for northern England on this run, but with model volatility as it is probably all gone next run 

I think with all the chopping and changing that fi really is tuesday,  and the only definite is the dates in the top left hand corner. Great learning curve for me though! 

[Winter Hill]

1 hour ago, Tim Bland said:

UKMO has it all over for England & wales by 96hrs so it’s a 3 day cold snap for most 

So by your analysis, England stops at Staffordshire.

[Mike Poole]

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!

Edited March 5, 2023 by Mike Poole

[sheikhy]

As the charts stand anyone living in the north midlands area should be pretty excited!!i say as it stands cos it will easily shift north and south next few runs!!even ukmo gives snow widely for much of the midlands on thursday and not just the north!!

[Snowman.]

6 minutes ago, TEITS said:

Only output im confident of is the possible snow moving S during Monday night/Tues. 

Apart from this the difference in the 0Z & 12Z UKMO is making me think its pointless looking beyond Tues. A special mention to our members in Scotland though is the chances of remaining cold throughout is looking more likely than I previously thought,

I shall take this though.

Good line of beefy showers, likely also downplayed by models which as we all know are not great at forecasting showers.

Probably the only thing the Met could plan a warning for. Everything regarding the slider or channel low may as well be a dartboard for outcomes.

[Bricriu]

I hope the GFS OP run has some support from its members. I bet it hasn't. It's a peach of a run from an imby perspective. 

[Tim Bland]

6 minutes ago, Winter Hill said:

So by your analysis, England stops at Staffordshire.

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

[Dignity]

9 minutes ago, TEITS said:

Only output im confident of is the possible snow moving S during Monday night/Tues. 

Apart from this the difference in the 0Z & 12Z UKMO is making me think its pointless looking beyond Tues. A special mention to our members in Scotland though is the chances of remaining cold throughout is looking more likely than I previously thought,

I shall take this though.

Ah yes we get it freezing up here and none of the white gold!

Not a trade off I want...

To keep it model related, I'm on the east coast of Scotland and a lot of the output has shown precipitation coming down from a cold northerly next couple of days. I would think I'm in with a chance at least.

[Snowy L]

7 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!

Look at the difference in Spain between GFS/UKMO and ECM. Northern Spain going green in the former two this afternoon, still orange with the ECM. Hopefully ECM comes on board with weakening those heights later.

[PiscesStar]

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

[Man With Beard]

3 minutes ago, 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 

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.

Edited March 5, 2023 by Man With Beard

[That ECM]

21 minutes ago, Man With Beard said:

UKMO also has snow potential tomorrow night, not a huge amount but there all the same

I’ll be up early Tuesday morning if this continues. A few hours of light flakes of joy would be welcome.

Edited March 5, 2023 by That ECM