Model output discussion - mid-winter

[feb1991blizzard]

3 minutes ago, mulzy said:

@johnholmes produced a superb guide on "will it snow" - would be good to link it here.

In which he states -5c or below is unlikely to produce snow in showers.

Edited January 10, 2018 by feb1991blizzard

[Methuselah]

And for a wee punt: 3-5C in Scotty, 4-6C elsewhere...except for +10C outside knocker's woodshed!

[Walsall Wood Snow]

1 minute ago, SLEETY said:

And  winter 17/18 in the uk will go down as one of the best ever in recent history for chasing cold for many ,but in the end it only delivered in the Scottish Highlands

Not forgetting much of the Midlands and Wales, where it has indeed so far been the best Winter since 2013. I wonder if much more of the UK had been so good in December the perception on here of this Winter might be better?

[andymusic]

looks flipping freezing to me from Monday onwards and if the southern tip of spain and the sahara desert can get snow then i'm sure most of the uk will see some snow out of next week

[frosty ground]

The GFS 12Z Run is colder for longer 

Vs06z

Edited January 10, 2018 by frosty ground

[SLEETY]

You need a lot lower than-5c hpa for snow to settle in a NW air flow,because of the humidity of the air as it has to cross the vast Atlantic Ocean,much different than an Easterly with the dryer air and much less sea track to contend with .

[Weathizard]

Looking good for some lucky of you lucky buggers! Regardless of that, this is a very interesting chart going forward for winter.. 

[mulzy]

3 minutes ago, frosty ground said:

The GFS 12Z Run is colder for longer 

Vs06z

The GFS has an 850 HPa bias where it too aggressive (as opposed to the GEM where it is too conservative).

Edited January 10, 2018 by mulzy

[andymusic]

very much some "bleak mid-winter" model watching here for next week - get your winter woollies on lol

[doctor32]

12 minutes ago, frosty ground said:

The UKM is under -5 especially for the Greater Manchester area. Cold for for snow with elevation...... Plus any shower activity is going to pack a punch and drag temps down.

Also the reply you replied to quoted both GFS and UKM.

We had -6 to -7.c uppers last weekend and only managed a bit of hail/sleet from showers at best from a cold north east flow, which at this time of year, you would have thought snow showers were guaranteed.

[feb1991blizzard]

If the GFS verified though, not only might places away from the usual snowy areas see a covering, the more favourable places could see some hefty accumulations and also this Greeny height rise looks very much on the menu, unlike the ECM.

[bluearmy]

3 minutes ago, andymusic said:

looks flipping freezing to me from Monday onwards and if the southern tip of spain and the sahara desert can get snow then i'm sure most of the uk will see some snow out of next week

The Sahara where it snowed is, I’m guessing pretty high up. The south of Spain with a continental flow could be anywhere on the continent. - it snowed in bloody Florida last week !! 

We are a small island at the eastern end of a huge ocean  - end of. 

[Seasonality]

 

1 minute ago, feb1991blizzard said:

If the GFS verified though, not only might places away from the usual snowy areas see a covering, the more favourable places could see some hefty accumulations and also this Greeny height rise looks very much on the menu, unlike the ECM.

Yes, the Greenland height rise is a theme that has been going for a good number of runs now. Stronger ridging on the 12z compared to the 06z with heights in evidence towards the pole too. 

[bluearmy]

Quite an interesting chart at T222 as the 18z was last night at T252. 

there is hope if we could get a gfs op to be anything like the day 10 output at day 3 ! 

[andymusic]

3 minutes ago, bluearmy said:

The Sahara where it snowed is, I’m guessing pretty high up. The south of Spain with a continental flow could be anywhere on the continent. - it snowed in bloody Florida last week !! 

We are a small island at the eastern end of a huge ocean  - end of. 

southern spain - ON THE BEACH

[karlos1983]

Given its fl, pretty good consistency from gfs 6z v 12z.. not sure I’ve ever said that ?

[SLEETY]

4 minutes ago, doctor32 said:

We had -6 to -7.c uppers last weekend and only managed a bit of hail/sleet from showers at best from a cold north east flow, which at this time of year, you would have thought snow showers were guaranteed.

You need at least -10  hpa for snow showers from a convective Easterly to GURANTEEfalling and lying snow,plus the North Sea is warmer than usual unless you live on high ground of course,same with this NW wind next week I think.

[SMU]

19 minutes ago, snowice said:

Hi Steve

Can you solve the uppers problem as some members don't think there cold for snow gfs UKmo look fine to me.

Will hav a look

it is borderline though 

 

 

[feb1991blizzard]

Just now, Seasonality said:

 

Yes, the Greenland height rise is a theme that has been going for a good number of runs now. Stronger ridging on the 12z compared to the 06z with heights in evidence towards the pole too. 

TBH I don't think it would end up a true GH as in late Dec 2010, I think it would soon topple, but obviously to Scandi, this time with much more frigid uppers to the East, if that trough thats sinking over us could elongate W-E, then we could be in business for a better attempt at a proper Easterly this time.

[Jason M]

19 minutes ago, ukpaul said:

What parameter do you think is out? GFS at -6 or -7 looks fine, dewpoints are good, I checked the 850-1000 on the morning run via weatheronline and they looked good, ground temps are zero or near below, I even checked the wet bulb freezing level, which was good (please note, I was focusing on Pennines but they appeared okay more widely) Now -4 would be poor in UKMO and -5 would likely need elevation, so there's the problem.

If those are the parameters at that point it might well be okay. The issue is more likely to be that the model might be overdoing some of them. Certainly not impossible given the time of year, but I'd view that as 'best case scenario' so everything has to fall right for most peeps. If I lived in the Pennines though I'd be dusting off the winter gear!!

[frosty ground]

 Day 10

Much colder air over Europe on this attempt.

[SLEETY]

Very close on day 10 Again from gfs,maybe it is on to something in  fl for once,as the output is similar at that range from last night 

[Seasonality]

If you ask me, UKMO and GFS t+144 seem to be broadly agreeing.

 

[Catacol]

3 hours ago, Glacier Point said:

Worth noting that the likely evolution of the coupled tropical wave in the next 10 days across the maritime continent is where the EC shows its weakest skill score. So this models' performance might just dip a little compared to the gfs. 

The 00z eps smacked of no coherent view for mid to latter part of week 2, albeit not much cluster variability.

Interesting Stewart. Is this overall skill score - or do you have access to data that is more relevant to a specific scenario compromising convection in the maritimes?

[doctor32]

1 minute ago, SLEETY said:

You need at least -10  hpa for snow showers from a convective Easterly to GURANTEEfalling and lying snow,plus the North Sea is warmer than usual unless you live on high ground of course,same with this NW wind next week I think.

-7.c normally the bench mark with right dew points to guarantee snow showers for north east england normally. i am 90m asl and well inland.

As you have pointed out though the warmer north sea or waters further north in artic may be playing a role this winter with us needing higher 850 uppers in showery flows?