Model output discussion - late November

[Mucka]

Everything is relative I guess. UKMO isn't great but it is a little better than GFS 18z last night and a fairly big improvement on a like for like with yesterday's UKMO 00z.

We are out of the queue and on the roller coaster at least.

[Cheshire Freeze]

2 minutes ago, northwestsnow said:

I wouldn't say its poor personally but compared to ICON yes, nowhere near as good.

Would still be very cold,esp at night as we hit next fri/sat/sun..

Depends what you're after. Such a topple scenario would/should be ten a penny in any winter.

Personally I'm after something a bit more robust looking with snow potential (other than scattered wintry showers)

[feb1991blizzard]

@CreweCold  Agree with you about short lived but i think we agreed ages ago that a strat-trop coupling was inevitable with a strong jet in December, so to get anything is a bonus, Its the second half of winter i am pinning my hopes on.

[northwestsnow]

GFS setting up for a polar north westerly by day 10...

[Mucka]

4 minutes ago, northwestsnow said:

GFS setting up for a polar north westerly by day 10...

LOL seeking redemption

Toasty up top again too.

Let's hope we can get something decent from the first attempt though.

GEM looking better early doors so a mixed bag so far this morning

 

 

[northwestsnow]

All in all a very respectable GFS 00z, lots of frosty weather and a 2 day cold north wester ...

I'm not greedy and my expectations, if i were to be brutally honest, are quite low.

An extended big freeze at this stage was not likely, IMO.

[knocker]

There is a large complex trough to the south west of the UK at midnight which contains ex TS Sebastien as can be seen on the 500mb and surface analysis 

In more detail.

The occlusions, and the trough, associated with the surface low to the west of Ireland will continue to track north east through today and belts of showery rain, with some heavier pulses, will effect most areas by dusk with showers and sunny intervals following behind the fronts. Meanwhile to the south west Sebastien is undergoing some rapid cyclogenisis

The frontal rain will continue through the night in the north of England and Scotland wjilst it will be much clearer further south but heavy rain will encroach the south west in the early hours as Sebastiien continues to deepen and track NNE

By midday Tuesday the low is 964mb south west Ireland and the bands of rain, heavy at times, associated with the fronts will sweep north through the day followed by frequent heavy showers with thunder in the mix.The winds will also and in particular it will be very windy in the south west  It will at least be relatively mild

Over Tuesday night and through Wednesday the low starts to fill and track east across Wales and central England resulting in bands of showers/rain running around within the circulation. But the overall pattern continues to evolve with a quite intense high cell in the Denmark Strait  with an energy flow running around the northern flank bringing colder air into play

And this becomes more obvious on Thursday as the low continues to fill and track into the North Sea and the wind veering northerly and turning colder in the north behind the weakening cold front

By Friday the high cell has slipped south east and with the colder air now in situ a much colder day ensues, albeit dry with sunny intervals

Edited November 25, 2019 by knocker

[knocker]

According to the gfs over the weekend the pattern upstream unfolds as previously discussed

And as far as the surface is concerned the frontal wave out in the Atlantic on Friday develops and tracks south east into France on Saturday perhaps bringing some rain along the south coast

And on Sunday a cold day with wintry showers in the north

 

Edited November 25, 2019 by knocker

[Mucka]

GFS Op wasn't great but on the plus side it is probably in the bottom 3rd of the ensembles for wintry potential.

Probably just as well it didn't spit out the best run to temper expectation

Still looks like a toppler but whether it is a worthwhile one or not as regards seeing some early season sleet/snow falling remains to be seen.

Short ensembles firming up on a few chilly days at least.

[northwestsnow]

Just now, Mucka said:

GFS Op wasn't great but on the plus side it is probably in the bottom 3rd of the ensembles for wintry potential.

Probably just as well it didn't spit out the best run to temper expectation

Still looks like a toppler but whether it is a worthwhile one or not as regards seeing some early season sleet/snow falling remains to be seen.

Short ensembles firming up on a few chilly days at least.

GEFS keep us cold from fri-tues so thats a 5 day cold spell, christmas tree/shopping/markets this weekend for many so defo feeling seasonal for the 1st weekend of Dec.

I'm happy with that

[Frosty.]

Nae Bad, Nae Bad at all for a Monday morning, or any other morning for that matter!!!!!❄

Edited November 25, 2019 by JON SNOW

[tinybill]

i  know its  la  la land  but  things might be starting  to get interesting  for the coldies  on  here!!!

[knocker]

The ext GEFS has a fairly diffuse tpv this morning with the main lobe and trough northern Canada/eastern N. Americ, with another extension into Europe.

Still a strong westerly upper flow exiting the eastern seaboard and around the quite substantial subtropical high in mid Atlantic and thus veered north westerly over the UK

 

[That ECM]

Ukmo and ecm t144. A lot of similarities but look at the south of the uk. Prefer ecm but more time need to see which is more correct.

[tight isobar]

Best set thus far...by a mile.

And the mid snap is very encouraging..with both expansion....and depth!!!!

[knocker]

The ecm a cold weekend with widespread frost, particularly Saturday morning with rain from the wave across southern regions

 

[BLAST FROM THE PAST]

4 hours ago, northwestsnow said:

TBH Crewe, its very rare to see a 3 or 4 day cold snap/spell during Decembers nowadays so with that in mind i'm happy

still going strong at 180hours.

Indeed, What I’m seeing is that when it gives way (and it will imo) the mild interlude doesn’t last long before another surge of cold from the NW/N.  By the 7th and 8th widespread -10c flooding the Uk...........FI yes......but The theme is of more cold than mild with resurgence after resurgence.

We are seeing the signs now of northerlies being of real potency this year with the colder SSTs to our West and to our N/NE

BFTP

Edited November 25, 2019 by BLAST FROM THE PAST

[IDO]

So with the Euro/Russian high migrating slowly east it has opened the door for a better NH profile for the UK to maybe get a suitable chance from the recurrence of cold spilling to mid-latitudes. 

The first chance, the Russian high remains too close and we are squeezed out of the snow chances as the trough drops, instead we get the northerly form the topple of the Atlantic ridge. So cold.

There has been a chance of a second cold shot before the wave pattern declines, when the Russian high is further east, after D10, so with an established Sceuro trough, maybe a better placement for snow, but FI for sure.

With the wave train of HP cells we remain in an effective mobile flow, with slow downs as forces collide, so no sign of an orthodox static amplified wave to enable long term blocking (ATM). So cold air shots look the best case scenario. Makes for a more varied start to winter than the norm.

[Tim Bland]

Looks like we’re back to a 2 day cold snap with wintry showers in the North east. GFS has been toying with the idea of another northerly exactly a week later for a while now. This one could pack more of a lunch and deliver the first snow for many 

[northwestsnow]

According  to the weather.us site EC det brings some very cold nights as we reach friday, moreso further north with the long nights probably contributing to sub zero mins ..

So, not bad really, no major freeze but at last some dry cold weather to enjoy for many..

BBC raw not really suggestive of low mins at the moment, IMBY the lowest they are forecasting is 0, i thought it might have been a bit lower given the airmass and time of year,perhaps there will be clouds in the flow..

[knocker]

The salient points of this morning's ext EPS

A diffuse tpv with trough extensions Canada >  eastern N. America  and Scandinavia > eastern Europe

Alaskan ridge

Strong upper flow exiting the eastern seaboard and around the subtropical high and thus veering as it arrives over the UK

Await the weeklies update tomorrow to see if Sidney's  Xmas barbie is still on track

 

Edited November 25, 2019 by knocker

[Methuselah]

It's only rock and roll but I like it!

    

Some of the best winters start with a wee run of topplers...

And, as a guide to the potential depth of cold, there's even a ice-day in there!

   

Edited November 25, 2019 by Ed Stone

[Skullzrulerz]

14 hours ago, Mike Poole said:

 



Based on current updates the AO is set to go highly positive with most members around 2-6

However the NAO looks to be going into a somewhat more neutral state or sightly positive at the turn of the month

[Jordan S]

The next couple of days looking Very unsettled with rain likely to cause a few issues potentially in particular late tomorrow into Wednesday.. 

Gem on tomorrow's low which contains the remnants of ex Sebastien..

6am tomorrow morning..

You can see a deep area of low pressure system to the south of Ireland which if the Gem is right could give a spell of very strong winds for a time with gales possible to there but Other models don't take this that far north so caution needed but an area of rain will push north into England and Wales into tomorrow morning with some particularly heavy rain likely for southern Ireland for a time aswell. 

But I'm going to focus on this area of rain here..

Tomorrow 6pm..

You can an area of particularly heavy rain to the west of France this is set to push northeast during Tuesday evening/overnight but the track is uncertain but it's likely to contain some very heavy downpours perhaps a few thunderstorms amongst more general heavy rainfall. 

Midnight tomorrow night..

 

Wednesday 6am..

Here's some various models output for this in a closer view..

Icon..

Pushes it through southern and central parts of England into the north of England during Tuesday afternoon into evening. 

Arpege..

The area of rain comes in later and is much further east with Arpege giving the far southeast a spell of particularly heavy rain before drifting off into the north sea. 

Hirlam..

Brings it in further west pushing northeast through England and Wales during Tuesday afternoon. 

Finally Arome..

More sporadic with this but some heavy downpours and perhaps thunderstorms pushing across Southeast England and also some pushing into the southwest of England and Wales after the initial frontal band of rain.. That is looking particularly heavy for southern Ireland. 

It may just drift north to the east of the UK resulting in just a few showers but if its further west then a soaking for central and Eastern areas. Something to keep an eye on. 

Edited November 25, 2019 by jordan smith

[StretfordEnd1996]

A bit of a mix and match this morning - perhaps in general a tad less colder for longer compared to yesterday but still a lot to digest and get excited about

GFS 00z op very similar to the 18z, bringing the HP toppling in 

It rises towards the NW by +144 but collapses in and over only a day or so later

But it'd still be cold for a (short) time - especially on Sunday with chilly uppers (though the uppers actually arrive by Friday)

However - similar to the 18z the op remains largely the mildest of the run between around D7-10 - this essentially means it topples 'first' before its other ensemble sisters

 

ECM is different - showing a much more longer and pronounced period of cold uppers from D5 through to almost D9 - 

They start coming in on Friday thanks to the weak ridge to the NW

A much more pronounced and 'proud' ridge to the West though compared to the GFS by D7

It's not even until D8 in which it begins to topple in - but at the same time the uppers remain freezing

UKMO looks a tad towards the GFS but to be honest I can't say this as fact as no idea what may happen after +144. Either way uppers still very cold

GEM similar to ECM with the cold lasting will into the next working week rather than toppling quickly

Way out in FI and only eye candy at the moment shows that after the initial HP collapses over the country another push happens towards Greenland

Way out and a big outlier and not even worth considering since it was already an outlier before this but a nice collection of ensembles also show a similar solution for the timeframe even though its a long way out

Looking forward to the next set of runs - GFS 6z look out for whether it brings the HP in quickly