Model Output Discussion - cold spell to end Autumn

[Frosty.]

I think the Ecm 12z is the best run of the winter so far!

[bluearmy]

2 minutes ago, feb1991blizzard said:

168?

168 onwards Feb 

such a more promising solution that the gfs back edge snow but no more likely at the moment 

[snowice]

6 minutes ago, bluearmy said:

Did anyone spot a wedge ??

No but ive seen a sledge 

[Pembroke Dangler]

1 minute ago, northwestsnow said:

Well dont rule out troughs in that northerly later next week

Guaranteed to be troughs the sst's are around 10 degrees with 850s of -8 on average convection will produce them and possibly thunder snow in some places where the clouds tower up.

[Scandinavian High.]

2 minutes ago, knocker said:

The ecm has the first wave from the front descending from the Iceland area impacting Scotland Weds 00 with heavy rain and strong winds. This rapidly clears east and by 12 the front associated with the elongated trough WSW of Ireland has arrived bringing more rain the Scotland.

Over the next 24 hours small waves form on the front as it slowly drifts south to be over central and southern England and Wales by 12 Thursday dumping a fair bit of rain as it progresses. Behind the front the surface wind veers northerly introducing clearer, colder air and wintry showers

The northerly regime continues through Friday but by 12 Saturday the ridge from the west is edging in and the winds back north westerly and abate. Very cold on Saturday with max temps not much above freezing.

But this ridge is very transient  and by Sunday 12 the next trough emitted from the Canadian vortex has been picked up by the 170kt jet south of Greenland and has tracked rapidy south east to be over Ireland by 12 on Sunday with heavy rain into Wales and the southwest or, and it’s a little ridiculous to be considering this at this range, some significant snowfalls in Wales and the south west as the warm air overrides the cold air in situ

From here it’s all hands to the pump as the low slips into France and we have a very complex trough area in the eastern Atlantic and NW Europe Are we perhaps looking at the jet swinging south of Greenland creating a cut off high cell to the north with low pressure to the south.

Hi knocker I’m fairly new to this form love reading your posts input on models by looking at the models do think it’s worth the while get sledge out the garage..

[Day 10]

2 minutes ago, RAIN RAIN RAIN said:

Does Iceland met still do those ECM charts that show uk? 

[feb1991blizzard]

3 minutes ago, RAIN RAIN RAIN said:

Does Iceland met still do those ECM charts that show uk? 

Just North of M4 corridor, South Wales and South East do best for snow, nothing exceptional but I believe there would be more should that setup verify.

[steveinsussex]

Please can I urge anyone tempted to go buy a sledge, tell friends or relatives, or post about the models runs elsewhere on social media NOT TO

 

You wiil only jinx it

 

Thanks

[Mokidugway]

Just now, feb1991blizzard said:

Just North of M4 corridor, South Wales and South East do best for snow, nothing exceptional but I believe there would be more should that setup verify.

I would imagine Wales getting a pasting from lake effect snow off the Irish Sea streamer from the northerly .

[Frosty.]

1 minute ago, abbie123 said:

Hi knocker I’m fairly new to this form love reading your posts input on models by looking at the models do think it’s worth the while get sledge out the garage..

There's something wintry lurking in the woodshed tonight!

The Big models have given us a superb 12z and I fully expect we will see many more stellar cold runs in the coming hours..days..weeks..months

[I remember Atlantic 252]

4 minutes ago, Pembroke Dangler said:

Guaranteed to be troughs the sst's are around 10 degrees with 850s of -8 on average convection will produce them and possibly thunder snow in some places where the clouds tower up.

Don't necessarily need troughs, all about the wind direction and convection off the sea, GFS looks good for snow Fri to Sun, Stockport to be buried, this looks decent flow for Cheshire Gap streamer for Midlands

[Pembroke Dangler]

The thing iv noticed over the years in slider scenarios is they tend to correct South and west nearer the time. I think this could well happen if the Azores high gets a bit more displaced to the west and alows a smoother progression of the energy heading towards Spain. The jet stream is certainly steering on a nw se axis on this chart so this could be locked in cold and snow for a atleast a week or ten days afterwards I would say. 

[Scandinavian High.]

16 minutes ago, bluearmy said:

Did anyone spot a wedge ??

Yes I remember you mentioned this the other day spot on..

[Mokidugway]

2 minutes ago, I remember Atlantic 252 said:

Don't necessarily need troughs, all about the wind direction and convection off the sea, GFS looks good for snow Fri to Sun, Stockport to be buried, this looks decent flow for Cheshire Gap streamer for Midlands

Yep ,looking good  ,not good news for Stockport free Tesco bus 

[feb1991blizzard]

3 minutes ago, Mokidugway said:

I would imagine Wales getting a pasting from lake effect snow off the Irish Sea streamer from the northerly .

 

3 minutes ago, Mokidugway said:

I would imagine Wales getting a pasting from lake effect snow off the Irish Sea streamer from the northerly .

Was looking at the wrong chart - sorry, that goes for all my other snow total reports on ECM, yes a heck of a lot, ranging from 4 or 5 inches to 20 inches in Wales, significant snow across Central England into Southern parts of Northern England / N.wales, South East England.

[knocker]

11 minutes ago, abbie123 said:

Hi knocker I’m fairly new to this form love reading your posts input on models by looking at the models do think it’s worth the while get sledge out the garage..

I would hang fire unless you are thinking of going to Norway  .

[Singularity]

Having ECM depict more of a wedge of higher heights scenario days 7-10 does feel like a watershed moment on the face of it... but in the past month we've already seen at least one case in which the models moved together only to ricochet off one another (so to speak!) the next day so it's far from a done deal given the range.

The northerly though is looking good for at least one day in the south and two in the north before it may turn more toward west depending on the pace of the incoming (probably) slider low.

It'd be good to see that low slowed a bit more to increase cold pooling ahead of it under the weak ridge that ECM shows - but then again, this would likely be accompanied by a shift SW in track and as GFS shows, that could mean a miss to the southwest for many or even all of us. Strange having that model showing the well-south version of events at such range and ECM not - did someone swap some of their cores around? 


IMO, the biggest gain that ECM has given us this evening is the persistence of the strongly poleward -ve EPO ridge as opposed to it being flattened. This improves the chances of the downstream pattern playing ball, regardless of the details such as timing of slider lows.

[Summer Sun]

UKMO t168 northerly frequent snow showers for some parts

[minus 9]

13 minutes ago, steveinsussex said:

Please can I urge anyone tempted to go buy a sledge, tell friends or relatives, or post about the models runs elsewhere on social media NOT TO

 

You wiil only jinx it

 

Thanks

I told the kids it would snow a few years back. Woke in the morning to heavy rain. Tears applenty. I keep quite now.....

[knocker]

2 minutes ago, Summer Sun said:

UKMO t168 northerly frequent snow showers for some parts

Will it cut off the jet?

[I remember Atlantic 252]

3 minutes ago, Summer Sun said:

UKMO t168 northerly frequent snow showers for some parts

Shame Iceland area not in view, see if any slider low, 

[Guest]

29 minutes ago, NorthernRab said:

Is -12'C 850 hPa for Scotland from an early December northerly not quite exceptional? 

From memory -16'C (maybe -17?) is the record and that was during the depths of a cold winter.

I think that you may well be right about the 850s record for "early" December cold spells - let's say the first half up to Dec 15th, although there is an example of a lower reading in late November 1890 with -18c 850s in south-eastern England (see the 5th chart below). Before I go further, I am somewhat sceptical about the GFS predictions for sub -12c 850s later this week. Whilst not completely impossible, I will be very surprised if we see anything below -10c. Some of the main reasons are the record low Arctic sea ice extent and the exceptionally high current sea surface temperatures there. Back in the 1960s and for much of the 18th century, the ice extent was more than 60% greater than today and often 500 to 1,000 miles further south, reaching the north shores of Iceland towards the end of the severest winters  I did an analysis of the Arctic temperature profile about 10 days ago in my long report on page 192 of the 1.9.17. model thread. I will also be doing an update on this as part of my next long report to be posted on here later tomorrow. In the meantime, it is interesting to look at some past early winter cold spells for a comparison - source NCEP Reanalysis on Meteoceil (link: http://www.meteociel.fr/modeles/archives/archives.php?mode=2&month=12&day=1&year=2010&map=1&type=ncep).

                             Dec 1st 2010                                                 Dec 11th 1981                                                 Dec 9th 1967                                         

                                              

                             Dec 4th 1961                                                 Nov 27th 1890                                                 Dec 5th 1879                

                                           

I have selected these events from my memory of those particular cold spells (well back to 1961 - not before then!). I may have missed several briefer early cold snaps in other winters. There have occasionally been much lower 850s later in winter and in particular coming in on a long fetch easterly - northerlies do get significantly modified, so south-east England has seen lower 850s than Scotland. I start with December 2010 and the 1st saw the lowest 850s in the first (of 2) severe cold spells that winter. -12s got into Scotland but on a polar continental air stream. An often quoted early cold spell was in December 1981. Like 2010 this consisted of 2 separate severe cold spells with northerlies and easterlies but nothing really below -8c 850s in the earlier spell. The late November and early December 1969 Arctic cold snaps saw some -8s but nothing lower (charts not shown). Another good northerly example was in December 1967. In fact sub -10s followed the day after a polar low and a very widespread snowfall. The extreme west of northern Scotland and the north of Northern Ireland saw -12s. The November 1962 Arctic cold snaps that preceded the big freeze from late December in the epic 1962/63 saw nothing much below -6s (charts not shown). The lesser quoted 1961/62 winter started off colder than the 1962/63 winter and ended December with very cold and snowy weather.  An early Arctic cold snap on December 4th saw sub -10s into northern Scotland and -12s in Shetland.  I then go back to the famous 1890/91 winter which had an even colder later November and December than 2010. Once again this was not Arctic weather but one of the earliest severe easterly spells of the last 200 years. It started in the last week of November and continued throughout December. Interestingly the lowest 850s were as early as November 27th with the whole UK under sub -10s, most of England under sub -12s, the south-east and East Anglia under sub -16s and east Kent under rather nippy sub -18s! The low countries saw sub -20s. Extraordinary for so early in the winter.  Both December 1878 (not shown as no exceptional 850s) and 1879 had extremely cold spells. December 5th 1879 saw sub -10s over much of England with a small area of sub -12s over the Lincolnshire coast. There are rather more January and February Arctic spells with sub -10s (Feb 1969 is a great example) and a few sub -20 easterlies (over south-east England such as Jan 1987).

Right, back tomorrow with my long report.

[karlos1983]

The ECM is a southerners dream. Which is why it’s not going to verify. Yes my mood is not great...... wonder why 

[Frosty.]

4 minutes ago, karlos1983 said:

The ECM is a southerners dream. Which is why it’s not going to verify. Yes my mood is not great...... wonder why 

Weather is more important than football, cheer up you've just seen the best ecm  run of the winter so far!

[karlos1983]

Just now, Frosty. said:

Weather is more important than football, cheer up you've just seen the best ecm  run of the winter so far!

It has helped, some parts of the country could get buried from that run. Best run for years never mind Winter Karl