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Model Output Discussion - The Start Of Winter


Paul

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

IDO, I think we were due one more round of the Canadian vortex before its due to weaken. So another pulse of the northern arm days 12/13 before we wonder what comes next...........

 

Yes a pattern change is beginning to gather credence for the last week of December and some sort of MLB (at least) in our region is the likely outcome. So another 5-7 days before we can get some guidance from the GEFS assuming its a strong signal.

 

A recent positive tweet: 

  anthonywx

@MattHugo81 Euro Weeklies yesterday show strong signal for -AO developing around/after Christmas.

05/12/2014 08:09

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Posted
  • Location: st albans
  • Location: st albans

Looks like the story middle part next week will be an east coast snowstorm in the states. having viewed joe b's blogs last few days, this will be another major flop by the gfs. Wonder if the para (not the one we can't currently see) , picked it.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Morning all

 

Not much change this morning overall but still some important differences within the broader pattern, the big question mark is upstream over the eastern USA and this comes down to whether  that low pressure moves up the coast of the ne USA or out to sea.

 

The ECM has made an improvement between T144 and T168hrs as a small shortwave runs east but separates from the upstream low and becomes absorbed by the troughing over the UK.

 

This keeps that small high pressure cell north intact,  upstream, the ECM/UKMO are in one camp and the GFS/GEM in the other more progressive solutions.

 

If you're a coldie you want the latter two to end up in the shredder!

 

In terms of the ECM ensemble spreads theres still enough support there for low heights digging into the Continent and whilst you have the Azores high stopped from ridging into that region you'll always have a chance of some PM shots.

Edited by nick sussex
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Posted
  • Location: Hertford
  • Weather Preferences: wintry the better
  • Location: Hertford

Apparently we had a solar hit on the 3rd of December what effect if any would this have on the models and how they perform or have indeed been performing ?

Thankyou

Emma

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

Apparently we had a solar hit on the 3rd of December what effect if any would this have on the models and how they perform or have indeed been performing ?

Thankyou

Emma

 

Hi Emma

I think we'll see more changes with more amplification as we progress as I think the jetstream will be affected by this solar/lunar period we enter.  ECM and UKMO and indeed yesterday GFS show signs the increased amplification.  Models can change fairly quickly as we saw late Nov when some were posting weeks of mild westerlies as a given, and that didn't happen at all.  Now I'm not advocating that we'll suddenly get a full GHP and / or Scandinavian block but I think we'll have more of a potent northerly set up initially next week with the Atlantic ridge being more influential than is currently projected.

 

 

BFTP

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

Hi Blast, What Solar/Lunar period are you talking of? Any Solar/Lunar activity over the past weeks or at any time will have no effect on the Models as to what they are showing, They do not use these measures.

Edited by Polar Maritime
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

The GFS 06 hrs run is much less progressive than the earlier 00hrs and has trended towards the Euro's.

 

I doubt this will be the last of the changes though with continued uncertainty over the ne USA set to last a lot longer.

 

I think the next uncertainty once the models agree on the pattern over there is how quick another shortwave tracks east across Arctic Canada and whether this phases with the low exiting the ne USA and how this impacts events in the mid Atlantic.

 

Quite a dramatic turn of events on this latest GFS run, typically the least favourable 00hrs output has now switched to the best for coldies on the 06hrs run, this highlights just how important the pattern is over in the USA, you'll also see earlier it makes more of the ridge out of Russia which helps to force more disruption on the UK troughing.

Edited by nick sussex
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Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)

Does anyone know what's happened to the GFS Paralell model? Hasn't seem to have updated since Wednesday 3rd December. :S

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Posted
  • Location: Reigate, Surrey 78m asl
  • Location: Reigate, Surrey 78m asl

DRL - I understand from a post from Paul a few days ago that the parallel is not being run for a few days as they are fixing the supercomputer!

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

Does anyone know what's happened to the GFS Paralell model? Hasn't seem to have updated since Wednesday 3rd December. :S

 

The supercomputer is getting some work done to it, it will be back for the 12z on Monday

Edited by Summer Sun
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Posted
  • Location: St rads Dover
  • Weather Preferences: Snow, T Storms.
  • Location: St rads Dover

Does anyone know what's happened to the GFS Paralell model? Hasn't seem to have updated since Wednesday 3rd December. :S

They are working on the computer it runs from, it will restart on Monday if I remember right.

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Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)

@Great Plum/Summer Sun/AlexisJ9: Ah, thanks guys. Should have known. :good:

Might as well just do a very quick summary while I'm at it, but still looking like a continuation of wintry North-Westerly flows and mild(ish) Westerly flows with a fairly mobile Atlantic pattern. Models also show some very stormy conditions during the middle of next week with that deep Low, which will still need watching. But it could certainly give some menacing gusts to places, most especially towards Northern areas.

Edited by DiagonalRedLine
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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

The 06z GFS seems more along the lines of the other 00z runs with deeper troughing into Europe.

This keeps the Azores high further west and prevents it building across mainland Europe to our south.This is key to hindering a milder setup.

 

At least this nw-se pattern is giving us chances of some cold north/north westerlies as they develop behind passing lows to our north.

It is a mobile pattern though so any Arctic incursions would be fairly brief but overall a rather cold outlook with snow over higher ground and night frosts.

Of course, as Nick S alluded to, further amplification upstream will make all the difference for the UK and increase the odds of getting deeper cold from the north as we would see much greater ridging of the Atlantic/Azores high.

Edited by phil nw.
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Posted
  • Location: Fenland Fylde.The same village as Duncan Iceglide.
  • Weather Preferences: LP - Horizontal Drizzle - Nice Blizzards
  • Location: Fenland Fylde.The same village as Duncan Iceglide.

When are the warnings issued?

 

post-6879-0-40326000-1417776308_thumb.pn

 

LP is further South on the 06Z.

 

Pennine whiteout conditions - with a possible 24hrs of ppn.

 

Ian

 

 

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

The GFS continues with a cool/cold theme, With bouts of Pm air from the N/W crossing the UK maybe turning Northerly at times in turn bringing some seasonal Wintry showers down to lower levels, And feeling raw especially in the wind. Stormy conditions especially for the North next Wednesday, With blizzard conditions over parts of the Highlands giving significant falls with over 50cm snow Model'd for the Scottish Mountains. No Zonal/Westerly Atlantic flow showing, With a very Meridional Jet. A cold night tonight with temps dropping down to -5/-6 in some rural locations.

 

hgt500-1000.pnghgt500-1000.pnghgt500-1000.png

Edited by Polar Maritime
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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK

One feature that has shown a significant presence has been the lower heights over Southern Europe. That's a better scenario for cold spells rather than the dreaded Euro High. As Nick F pointed not enough height protracting poleward yet for substained cold spell but currently better than none. However, the lower heights over Southern Europe gives us a better chance of cold if the synoptics show linking of the Arctic highs and then bingo a snow fest prospective with the kind of trough distruption that Nick Sussex reports. To get there, ECM looks a better bet than GFS, but still some doubt about the changes taking place in NE America. Anyway, looks better for you guys so far than this time last year. I did note some low day time temperatures across the SE of England yesterday, probabaly the coldest day temps since March 2013 ? Maybe this is a good omen if you like cold !

C

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Posted
  • Location: Wellseborne, Warwickshire
  • Weather Preferences: Southerly tracking low pressure in winter. Hot and thundery in the summer
  • Location: Wellseborne, Warwickshire

Much better amplification on this run which is in itself surprising being 06z ,

post-9095-0-88185000-1417777149_thumb.jppost-9095-0-72503700-1417777166_thumb.jp

When compared to the 0z you can see the difference in the pattern , vortex also looks like it's weakening somewhat with low hights draining from Greenland .

post-9095-0-69626300-1417777276_thumb.jp

Models are beginning to show signs of moving toward a more blocked outlook toward the last 3rd of the month , also on this run the siberian high is much more of a player than recently , it's March west has begun , more importantly is the removal of Asian low hights , with the return of the Siberian high will allow wave activity to resume again , which of course bodes well for further down the line , still the Xmas period is bench marked as what could be a very interesting period synopticaly at the very least .

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

Yes little change on the 06z GFS op with respect to the bigger picture, that is a rather changeable zonal pattern for the next 2 weeks; but with a shift to more amplified short wave features, so trending to the cooler flow (uppers) of the ECM. At the end of the run we see the continuation of the low heights being removed from our NW and tentative signs of heights; ML and maybe HL:

 

post-14819-0-12800900-1417776642_thumb.p

 

The GEM ensembles are also showing the migration of much of the Canadian (et al) vortex to Siberia, but further east than the GEFS. This suggests heights more likely to build further upstream than Greenland in respect to the GEFS take. Looking at the mean more like the West coast of the US:

 

post-14819-0-74759200-1417777023_thumb.p

 

Not great for cold in the medium term for the UK but some sort of potential upwelling anywhere is appreciated. The CFS Daily update is as of yesterday with attempts to build heights in Greenland then Scandi looking promising, but then over ridden by the PV mobility and again late in FI:

 

post-14819-0-63737400-1417777325_thumb.p

 

That may all be academic as the warming continues on the 06z: post-14819-0-12490300-1417777405_thumb.p

 

So a cool period upcoming especially for the north with three PM incursions. And on D5-6 we have the storm. Control:

 

post-14819-0-76607000-1417777544_thumb.p   In 4 days it is developing to hurricane force: post-14819-0-97574000-1417777907_thumb.g

Edited by i'm dreaming of...
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

A very complicated upstream picture is developing which makes any outlook difficult.

 

We're looking at several key points which effects cold advection into the UK, firstly the eastern USA low track and depth, then what happens to a shortwave at the base of this, you'll see that the GFS takes this shortwave ejects it eastwards and leaves behind the main low which then phases with another from Arctic Canada.

 

post-1206-0-82833300-1417778666_thumb.pn

 

Over Europe the GFS 06 hrs run pushes in that ridge from the east which stops the low from moving east and eventually helps to add some forcing to aid some trough disruption:

 

post-1206-0-87080900-1417778995_thumb.pn

 

In terms of pattern upstream the ECM and GFS 06hrs run broadly agree, the shortwave gets ejected eastwards and remains separate which then doesn't pull the USA low eastwards.

 

The next possible impact for the UK is how the Arctic Canada low phases with the one near Newfoundland and how much energy spills east and how this impacts any high to the west or nw of the UK.

 

As you can see by comments from NCEP theres too much spread in the solutions and ensembles to make any forecast unreliable:

 

AMONG THE TWO AREAS OF INTEREST THE EAST COAST APPEARS TO HAVE THE
GREATER FCST COMPLEXITY.  AS THE UPR TROUGH REACHES THE ERN STATES
DURING THE FIRST HALF OF NEXT WEEK THE FEATURE WILL LIKELY
INCORPORATE MULTIPLE PIECES OF ENERGY... SOME FROM PAC FLOW
CROSSING THE LOWER 48 AND THE REMAINDER ORIGINATING FROM NWRN
CANADA.  THE INCLUSION OF HIGHER LATITUDE ENERGY IN PARTICULAR
TENDS TO BE PROBLEMATIC AS IT USUALLY TAKES LONGER FOR GUIDANCE TO
RESOLVE IMPORTANT DETAILS RELATIVE TO MID-LATITUDE FLOW
.

 

Further on into the discussion:

 

THOUGH ADDITION OF THE
NEW 00Z UKMET/CMC SEEM TO INCREASE THE POTENTIAL FOR A SOMEWHAT
WRN SFC TRACK FOR AT LEAST A PORTION OF THE MON-WED PERIOD.  AT
THE VERY LEAST THE 12Z CANADIAN ENSEMBLE MEAN SUPPORTS THE ECMWF
MEAN IDEA OF HINTING AT SOME FLOW SEPARATION ALOFT AND BETTER
DOWNSTREAM RIDGING COMPARED TO RECENT GEFS MEANS.

 

The full discussion can be found here:

 

http://www.hpc.ncep.noaa.gov/discussions/pmdepd.html

 

Given the upstream complexities this could lead to either more of a damp squib in terms of cold for the UK or equally there might see some more interesting developments around the T144 to T168hrs timeframe with more digging south of the UK troughing and a stronger ridge to the west.

 

We also need to pay attention to that Russian ridge to see if it can make more headway especially towards the Svalbard region and Scandi.

 

So alot going on both upstream and downstream, hopefully the cards fall kindly for cold lovers and  the best possible outcome is delivered. I don't mind uncertainty as long as its resolved towards the colder spectrum of solutions!
 

 

 

 

 

 

 

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

Hi Blast, What Solar/Lunar period are you talking of? Any Solar/Lunar activity over the past weeks or at any time will have no effect on the Models as to what they are showing, They do not use these measures.

I'm saying the models are wrong in their longer outlook, i know they don't factor them in. The pattern I believe will become more amplified due to the solar and lunar effects on the jetstream.......and as if by magic the 06z rolls out.

 

 

BFTP

Edited by BLAST FROM THE PAST
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Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

Just posted the following into the NH Snow and Ice thread, but it does perhaps make for more relevant reading in here as well.  :good:

 

https://forum.netweather.tv/topic/81111-snow-and-ice-in-the-northern-hemisphere-autumnwinter-2014/?p=3081067

 

 

Cheers

 

gottolovethisweather

Edited by gottolovethisweather
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