Model Output Discussion - cold spell to end Autumn

[Weather-history]

UKMO 144hr...hmmm

Edited December 5, 2017 by Weather-history

[northwestsnow]

GFS 00z is EPIC !!!!! 

[Snowy Hibbo]

Week 1 (5-11 Dec)

Key features are the Atlantic ridge, Scandi troughing, Strong Aleutian low, +PNA. And of course the -AO.

UK looks mostly drier than normal, except north Scotland 

Week 2 (12-18 Dec)

Euro trough intensifies, -AO consolidates, Aleutian low enlargens. Ireland and Western Great Britain looks dry, and Eastern Great Britain looks wetter than normal.

Week 3 (19-25 Dec)

-AO, Atlantic troughing, Aleutian still strong.... Scotland drier than normal, rest of UK average.

Week 4 26 Dec-1 Jan

-AO still present, Aleutian low finally starting to weaken. Wetter than normal for England and Ireland.

Update on the POAMA MJO probability forecasts.

5-9 Dec: 70-90% Phase 6

10-14 Dec: 50-70% Weak, 30-50% Phase 7

15-19 Dec: 10-30% Phase 6, 10-30% Phase 7, 30-50% Weak

20-24 Dec: 10-30% Phase 7, 10-30% Phase 8, 10-30% Phase 2, 30-50% Weak.

25-29 Dec: 10-30% Phase 7, 10-30% Phase 8, 10-30% Phase 1, 30-50% Weak

30 Dec-3 Jan: 30-50% Weak, 30-50% Phase 2

4-8 Jan: 30-50% Weak, 10-30% Phase 2, 10-30% Phase 3

[northwestsnow]

1 minute ago, Weather-history said:

UKMO 144hr...hmmm

For gods sake- its just not possible to get alignment when one looks brill.

 

[igloo]

this slider looks more and more like a non event its getting further west with each run western ireland looks about the only place which might see something from this the next slider looks more likely to bring something better fingers crossed

[CanadaAl]

1 minute ago, igloo said:

this slider looks more and more like a non event its getting further west with each run western ireland looks about the only place which might see something from this the next slider looks more likely to bring something better fingers crossed

Yeah it does seem that way, still time will only tell. Also the system moving through on Monday afternoon has corrected south meaning most are missing out on a good dumping. 

[northwestsnow]

Looking at the 850s on ukmo its very cold at 120 so the low will be running into cold air...looks quite slack too think i will leave that one to the experts...:)

[northwestsnow]

edit 850s on ukmo 144 are pants...

Still, don't think the track of the low is nailed yet, and possibly might not be until 72

[northwestsnow]

GEM

3 out of 3 showing a different progression!!

Edited December 5, 2017 by northwestsnow

[TSNWK]

Should we be concerned about the UKMO ? If my learning is correct the positive tilt of the 980 shortwave to left of Iceland suggests it will barrel across to the north of us and flatten the lot...

Edited December 5, 2017 by TSNWK

[Chesil View]

1 hour ago, northwestsnow said:

GFS 00z is EPIC !!!!! 

it's certainly epic for Dorset. 

[shaky]

The low slides on the ukmo!!its a fantastic start to the day!!over to the ecm!!

[northwestsnow]

3 minutes ago, shaky said:

The low slides on the ukmo!!its a fantastic start to the day!!over to the ecm!!

Concerned about the 850s shakster!!( but im aware thats not the beall and endall)

More knowledgable than me will know more

[frosty ground]

43 minutes ago, northwestsnow said:

edit 850s on ukmo 144 are pants...

Still, don't think the track of the low is nailed yet, and possibly might not be until 72

Looks okay to me if you are north and east of the lows your okay..... 

[shaky]

Ecm.is not very good at 120 hours!!seems to be blowing up that shortwave far too often!!hope its wrong!!at least the ukmo and gfs look good though!!

[frosty ground]

5 minutes ago, shaky said:

Ecm.is not very good at 120 hours!!seems to be blowing up that shortwave far too often!!hope its wrong!!at least the ukmo and gfs look good though!!

Still gonna slide 

Just to the east of us....... I can feel the toys being prepped for throwing 

Edited December 5, 2017 by frosty ground

[That ECM]

All 3 at t120 and the differences are apparent. This could go down to t48 even t24 before any real confidence. The thing is though,  that won't be the only chance. At t144 the differences are very apparent!! Not long before we should use the fax charts for guidance on this initial situation .

Edited December 5, 2017 by That ECM

[frosty ground]

UKM in the middle of the three.... they will converge somewhere.

[frosty ground]

Another northerly but this lacks and potency..... cold and wet.

[Captain Shortwave]

Day 6 charts

ECM

The low can barely be called a slider now, it just feeds straight into the trough to our east, for most we would see more rain than snow with the mild sector not being removed. This also affects conditions after the fronts have cleared, mainly as it is the difference between surface temperatures remaining cold or a more standard clearance to a west/north west wind with temperatures near normal.

UKMO

The low sinks south east through the western side of the UK, a cold continental feed ahead of it should mean snow for the midland north (well until we hit the clearer weather of course)

GFS

The first low is already on the French coast as it has move further south and at a much quicker pace, the next low is moving in.

As you can see, there are so many complications here, for example the UKMO/GFS show further secondary lows moving along the base of the jet, the ECM actually looks a bit too clean compared to the other tow but that mightbe because of the lackof forcing from any weak heights.The end game is still okay as you will get the northerly as the low clears east and feeds into the main Euro trough, but it is the difference between a rather prolonged cold spell and a spell which sees temperatures oscillate between cold and less cold as shown on the ECM.

[frosty ground]

3 minutes ago, Captain Shortwave said:

but it is the difference between a rather prolonged cold spell and a spell which sees temperatures oscillate between cold and less cold as shown on the EC

It is the most likely outcome and would sit nicely with the UKM forecst. Of course this pattern is unpredictable and surprise snowfalls can not be ruled out

[frosty ground]

And yet another low about to dive into Europe.. .. 

All academic at this range 

I think 850's remain below 0 from Thursday..... Lots to keep any eye out for

Edited December 5, 2017 by frosty ground

[Man With Beard]

ECM this morning has a spell of snow from Midlands north on leading edge but quickly reverts back to rain except for Scottish hills. 

It's way out compared to the other models, and would have been in the outlier cluster against its own ensembles last night - but that doesn't make it wrong of course.

GFS slides very cold for a good week, UKMO slides but is in the middle (and probably the snowiest taking the country as a whole)

GEM and ARGEPE also slide.

[SMU]

Morning All

well after yesterday & if you fancied yourself as a bit of a mystic meg you could have almost have predicted the 00z runs to 192

GFS fantastic, UKMO almost as good-

ECM - progressive to the EAST..

it will be an interesting scenario to watch but the ECM ( based on history ) will be wrong with the track....

lots of snow to come for some this weekend & a string of days with sub 2c maxima- maybe 6-7 at least...

S

PS at least ECM finishes with a 4 wave pattern !

Edited December 5, 2017 by Steve Murr

[Man With Beard]

Winds also important for the far north - ECM and ARGEPE both going for 100mph gusts for Thursday. GFS slightly more moderate at 70-80mph at the peak. Gales through most of Scotland.