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Model output discussion - heading into 2018


Paul
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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Arpege has any snow arriving in the early hours of Wednesday for Wales and central southern England before clearing away during the morning and afternoon for Kent

36_ukpreciptype.thumb.png.e3b4a98518b697a47ab0695086a58f6c.png40_ukpreciptype.thumb.png.7b0eedac229d4d125fdfc415f5f263f6.png46_ukpreciptype.thumb.png.eda598ffc8c6f23a628b34a8f79920fc.png51_ukpreciptype.thumb.png.37483c3514064c4d359377ea88d5cf98.png

 

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Posted
  • Location: st albans
  • Location: st albans
13 minutes ago, Larger than average Hobo said:

Looking to be a repeat of two weeks ago then, with the main snow band crossing the south and little action for the north. Oh well .... ?

At the moment, most of the snow predicted by the models away from wales and the Midlands is to do with the wrap around behind the low - that’s surely a more tricky feature to predict ??

ecm is a little later now on the swing ne 

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL

Again, fingers crossed for you guys across wales the midlands and the south :)

Hopefully as many as pos get a decent covering tomorrow into wed- Ec snow depth charts look terrific - Euro4 however is not great, certainly for lying snow- i'm not a big fan of euro4 personally, i happen to think it underplays the snow signal- i might be wrong but thats my opinion.

Further afield- EC still alternating between PM/TM air as get to New years- 

Th trend over the last 48 hours has been a positive one for coldies IMHO- day 10 on EC has me believing we could see this seeminlgy endless conveyor of depressions of the ES abruptly closed down thereafter :)

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

Looking through ECM ensembles and, again, mainly westerly into the first week of 2018 but with many members going for "interruptions" - occasionally back edge northerlies as systems pass through. I don't see any reason for writing off the next two weeks from a wintry point of view (unless you're looking for consecutive ice days), and there are two good reasons 1. there's still enough amplification in the pattern to draw colder air towards the UK at times and 2. I see no decent signal for heights to establish in Europe. 

It's not classic wintry synoptics but it's still better than many recent winters, and probably less frustrating than chasing easterlies that never quite make it here.

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Posted
  • Location: Norway
  • Location: Norway
3 minutes ago, Man With Beard said:

Looking through ECM ensembles and, again, mainly westerly into the first week of 2018 but with many members going for "interruptions" - occasionally back edge northerlies as systems pass through. I don't see any reason for writing off the next two weeks from a wintry point of view (unless you're looking for consecutive ice days), and there are two good reasons 1. there's still enough amplification in the pattern to draw colder air towards the UK at times and 2. I see no decent signal for heights to establish in Europe. 

It's not classic wintry synoptics but it's still better than many recent winters, and probably less frustrating than chasing easterlies that never quite make it here.

i do see...

78.gif

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Posted
  • Location: leicester
  • Location: leicester
5 minutes ago, Dennis said:

so open your eyes :D

87.jpg

Good god could  be some crazy accumulation widely!!that looks torrential!!latest icon is an upgrade for midlamds again!!

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Posted
  • Location: West/East/Sussex Surrey border
  • Location: West/East/Sussex Surrey border

Icon is much more quicker at getting the precipitation across the country, its all gone by lunchtime and is very marginal for the SE, sweet spot maybe Oxford ish, whereas the GFS still has it across eastern counties at 7pm wednesday....

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

3 out of 5 ECM clusters have a trough-ridge-trough pattern after New Year that could provide cold interest for 24-48 hours.

ec-ens_nat_z500scenarios_2017122512_168.

By D12, ridging still struggling to get into Europe and I'm drawn to heights building over Canada - not for the first time on the clusters - good news for the anti-zonal crew:

ec-ens_nat_z500scenarios_2017122512_288.

 

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Posted
  • Location: st albans
  • Location: st albans
Just now, Man With Beard said:

3 out of 5 ECM clusters have a trough-ridge-trough pattern after New Year that could provide cold interest for 24-48 hours.

ec-ens_nat_z500scenarios_2017122512_168.

By D12, ridging still struggling to get into Europe and I'm drawn to heights building over Canada - not for the first time on the clusters - good news for the anti-zonal crew:

ec-ens_nat_z500scenarios_2017122512_288.

 

one of the three clusters in the extended is a nw/se jet into Europe with a mean Atlantic ridge. in fact two of the three clusters are non euro high heights (as opposed to the story of the ec 46 which is Icelandic trough and euro ridge)

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Posted
  • Location: Somerset/Devon border, 220masl
  • Weather Preferences: See if you can guess
  • Location: Somerset/Devon border, 220masl

Ridging over E Canada has hinted at by the CFS weeklies recently. I know this model gets a lot of stick, but I think it isn't too bad really.

Hope everyone has had a great Xmas Day!

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

Chance of thunder snow maybe?:D

iconeu_uk1-1-30-0.png

iconeu_uk1-42-30-0.png

iconeu_uk1-45-30-0.png

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Posted
  • Location: Melbourne, Victoria, Australia.
  • Weather Preferences: Snowfall obviously.
  • Location: Melbourne, Victoria, Australia.
On 25/12/2017 at 09:58, Catacol said:

Of course. Loss of AAM in the tropics is transferred as a higher AAM budget in the extra tropics. It is the loss of tropical AAM that has effectively hamstrung the recent forecasts for more blocked conditions at higher latitude for January as we observe westerlies taking control through our sector of the Atlantic.

The GWO is an index of net AAM in the system - and the inverse relationship between AAM at tropical and extra tropical latitudes is reflected in its value. It has nothing to do with me as to how this is related - it is a calculation that states the condition of GLAAM. Analogue data would suggest that in a Nina base state GLAAM tends to fall.. and with it chances of high lat blocking reduce as winter progresses. Hence the general idea that in a Nina year cold will tend to be front loaded. What was interesting about this year was that GLAAM levels looked to be holding up, as favourable MJO amplitude working alongside a -AO.

We have now seen this reverse... and the only question worth answering in my mind is why. Finally, after literally weeks of waiting and a few texts directly to WDT, we have updates for key AAM drivers. Frictional torques have been negative the last couple of weeks and are only just beginning to trend faintly positive

Frictional Torque

while global mountain torque has tanked through the floor almost off the scale

 

Mountain Torque

I really wish this data had been available over the last 10 days or so rather than not updating as expected at WDT (since 6th Dec) as it would have allowed a much earlier "warning" sign to those looking for cold that a change around was in the air. However it all falls into line with what I posted yesterday: stalled tropical signal combined with negative torques helping to scrub westerlies from the tropics and allow the trades to fire up once again. Net result = +NAO regime as westerlies take hold in the north atlantic.

What would cause both torques to fall and the MJO to stall? I cant answer that right now. There's a lot of chicken and egg about all this. I'm hungry to know more... and I'll keep hunting.

That's really weird IMO. I thought the EAMT went positive during that period, resulting to the current NP jet extension, and the Okhotsk low. And now the WDT charts aren't loading the current update for me. Very weird....

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Posted
  • Location: Camborne
  • Location: Camborne

The ecm also dabbles with some explosive cyclogenesis albeit not quite the same scenario as the gfs  but it does agree on some very unsettled weather.

Friday sees a very active front running east south of Iceland and then south over Ireland which quickly crosses the UK with patchy rain, perhaps snow on the higher ground to the north. From this point until Tuesday 00 the upper trough dominates proceedings in the eastern Atlantic resulting in a complex surface analysis which boils down to sundry systems affecting the UK, thus intermittent periods of rain, perhaps snow over the higher ground in the north, and very windy at times. Temps quite variable in this mobile pattern but varying around the average.

From this point renewed amplification occurs with the upper trough to the east disrupting south of the UK whilst the Azores HP ridges north to the west.but such is the energy leaving the eastern seaboard that by Thursday the ridge is flattened with systems once more racing east albeit now tending towards a N/S split.

ecm_mslp_uv850_natl_6.thumb.png.e349f4ffdbc45847b26e77a50a70483c.pngecm_mslp_uv850_natl_7.thumb.png.b4ee9e9fed0a8923103717909c680600.pngecm_mslp_uv850_natl_8.thumb.png.d06d6270c36c2c07187d354fdae7e2d2.png

ecm_z500a_5d_nh_11.thumb.png.230f188f79af69053e54ba72763fbada.png

 

 

 

 

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