Model output discussion - The Hunt For Cold

[BLAST FROM THE PAST]

06z a colder run for sure up to t216

BFTP

[Frosty.]

By late october standards, the Gfs 6z operational looks very wintry with frosts becoming more widespread, a risk of icy patches and showers becoming increasingly wintry with snow in places, even across the south..looking good!

[BlueHedgehog074]

Only a small thing really - as an example for next Saturday during the Northerly, the -5/6/7*C 850 hPa temperatures are a bit less diluted over the U.K on the GFS 06Z, than they were on the 00Z run.

GFS 00Z:

GFS 06Z:

May mean any showers over inland areas of the U.K. having more of a wintry element to them at lower levels. (Still would be very marginal towards coastal areas, though, with the best chance of snow over high ground - especially towards Northern U.K and into Scotland). 

The potency of the 850 hPa temperatures will, I imagine, vary from run to run with variations of the Northerly likely as it’s still some days away. The distribution of the cold 850 hPa temperatures over the U.K consequently having an affect on how wintry any showers or longer spells of precipitation will be as well as other aspects, such as whether the dew points will be around or below freezing, having evaporative cooling (helped by heavy precipitation), and things like that. 

[Frosty.]

Looking at the GEFS 6z mean / postage stamps..winter is coming guys..expect frosty nights, icy stretches and a risk of snow just about anywhere for a time but more especially further north at elevation BUT a sharp wintry arctic shot / shock is on the way!!..I can't wait!!☺

Edited October 21, 2018 by Frosty.

[SLEETY]

le

29 minutes ago, Frosty. said:

Looking at the GEFS 6z mean / postage stamps..winter is coming guys..expect frosty nights, icy stretches and a risk of snow just about anywhere for a time but more especially further north at elevation BUT a sharp wintry arctic shot / shock is on the way!!..I can't wait!!☺

hopefully the prologue of a prolonged cold and snowy winter.We are most certainly due one Frosty .Lets hope the weather gods agree 

[Kirkcaldy Weather]

2 hours ago, Steve Murr said:

Yet another GFS run- yet more Scandi heights recovered...

The -8c Line digging further & further South into Northern Europe

thats a pretty cold chart for the ESE @192..

Yes Steve this has been a theme on some of the GEFS runs too recently, hopefully a growing trend through the next week within the models 

main gfs run  P1  P5 keen on building a scandi high late in the run with a small cold pool lurking to the east      P20 also thinking the scandi high route at the end of the run  the northerly still on track  

[Methuselah]

One thing's for certain - Trawscoed won't be anywhere near 23C, this Halloween!

[Ross90]

That looks like quite a big change from previous runs with the low further west instead of right over or just to the east for the first weekend in Nov.

[Dominic Carey]

22 minutes ago, Ross90 said:

That looks like quite a big change from previous runs with the low further west instead of right over or just to the east for the first weekend in Nov.

Is that good in terms of cold weather?

[SMU]

yes @Kirkcaldy Weather 

Interestingly P5 demonstrates that the entrance to Nov ( poss even last week of Oct ) is the tipping point for continental flows-

Before the tipping point - get an Easterly through central Europe & cool air warms as it travels west -

However now in Nov even the most modest of cold pools can develop into -10c air as it decends-

See P5 covering 4 days

[Skullzrulerz]

53 minutes ago, Ross90 said:

That looks like quite a big change from previous runs with the low further west instead of right over or just to the east for the first weekend in Nov.

Can you explain this please as what will the outcome be ? 

[Derecho]

Hello

12z's coming out soon so I thought I would summarise. A very nice week on the way before a shock to the system on Friday!

A really impressive chart this with high pressure extending from the Azores well into the arctic. The 06z GFS looks to make the northerly for the weekend even colder with -5C uppers widely across the UK on Saturday. Snow at lower levels in Scotland is a realistic bet with some also on higher ground in the west. This synoptic setup is similar to October 2008 though so there may be some surprises.

It requires a clean hit though, the ECM doesn't quite manage that but is still cold:



ECM has things a bit further west.

Later on there is evidence the high could ridge to Scandi:



This would make it a 5 day cold snap at least rather then just a brief toppler. Some of the runs develop a really vigorous low over central Europeas warm air from Africa clashes with the arctic air. Don't pay attention to the sudden breakdowns at t240, GFS low res tends to do that...

Edited October 21, 2018 by Quicksilver1989

[Ross90]

22 minutes ago, Skullzrulerz said:

Can you explain this please as what will the outcome be ? 

A more experienced model watcher would give a far better explanation, mine was just an observation on Kirkcaldy Weathers post.It looks like we're in more of a cool rather than cold flow for the first week in Nov.

[Frosty.]

That's a cracking Ecm 00z ensemble mean for next weekend..all coldies will be happy with this!..I think some of us have a very good chance of seeing snow falling before the end of october for the first time in 10 years!!

[Met4Cast]

ICON is chart of the season for me today.

Northerly to toppler to Scandi heights and a cut off low to the South. Incredible synoptics.

[SMU]

^^^ Yes remember just 24-36 hours ago there was no Scandi High- now we see one developing

The fact we see one on the cards shows how vulnerable the jet is ATM

Edited October 21, 2018 by Steve Murr

[SMU]

Just look how far we have come with the ridge extension in 48 hours

12z today V 12z 2 days ago

Edited October 21, 2018 by Steve Murr

[Skullzrulerz]

3 minutes ago, Steve Murr said:

Just look how far we have come with the ridge extension in 48 hours

12z today V 12z 2 days ago

Through great news it's still a fair bit of way to go through i will admit it has done the northerly well its just what happeneds after is what we need to know hopefully...Fingers crossed we may get lucky and pull through

[The PIT]

Looking like a shock to the system for many at the end of the week. Should provide some more Snow on the mountains and cold wet conditions for some coastal areas exposed to the winds. Inland though it looks mostly dry though and I may have to scrap the wind screen for the first time this Autumn.

[Mike Poole]

I take it we can bank the northerly next weekend, GFS keen on the Scandi high thereafter, here T234:

My interest now is how this affects the strat PV, given there is still some weeks to winter. 

[Cheshire Freeze]

13 minutes ago, Mike Poole said:

I take it we can bank the northerly next weekend, GFS keen on the Scandi high thereafter, here T234:

My interest now is how this affects the strat PV, given there is still some weeks to winter. 

Ideally we want to trigger an early warming (CW)...it would help us out going forward.

[Leo97t]

How exactly is a ssw triggered? 

[BlueHedgehog074]

4 minutes ago, CreweCold said:

Ideally we want to trigger an early warming (CW)...it would help us out going forward.

I’m guessing CW stands for Canadian Warming? 

[mb018538]

Looks decent next weekend and maybe a couple of days after, but fairly short lived at this range....with the AO/NAO both predicted to recover to positive into November and the PV perhaps reorganising too in the 10-15 day range. We will see.

[booferking]

Pv starting to gain a bit more strength late on gfs will be interesting to see how this pans out going through Nov, met office going for blocking to the north & more changable weather further south.