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Model Output Discussion 29th December - Into mid-Winter.


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Posted
  • Location: Isle Of Lewis
  • Weather Preferences: Wild!
  • Location: Isle Of Lewis
Just now, mb018538 said:

Erm, are we looking at the same charts here?? Looks pretty Atlantic dominated to me!

ECH1-216.GIF?25-12

gefsens850London0.png

Ensembles also have no cold members, and plenty of ppn throughout. Unsettled.

Personally think it will take another stratospheric warming over the poles to weaken the strength of the PV. I noticed on the second last chart just how sausage like the PV is forecast to be. Another warming event will almost certainly split that... then the fun and games could begin. I have no idea how close we are to a reversal of the QBO... its overdue.. and Im still trying to work out where the MJO fits into this as well! Given how dry and non typical this winter has been so far I wouldnt be surprised if we see something special late winter. Show isnt over!

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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

Lets look at the ARPPOEUR  shorter range model at 102t. Still a lot can change over this time span and models out to 120t will chop and change again over the coming 48 hours. This picture shows a tightening of the flow south of 50 N with upper zonal flow winds pushing more into the continent rather than the British Isles. What effect this has on  eroding the Euro cold block is not determined as yet regarding the future shorter term synoptics. I think a lot can change and quickly develop  over this coming weekend.  I have a feeling that Euro cold will not give in as quickly as shown on most of the models this morning.

 C

ARPOPEU00_102_1.png

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Posted
  • Location: Croydon. South London. 161 ft asl
  • Weather Preferences: Thunderstorms, snow, warm sunny days.
  • Location: Croydon. South London. 161 ft asl

The GEM gets the first low pressure across to Scandinavia and the ridge builds in behind it forcing the jet SE.

 

gemnh-0-204.png

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
25 minutes ago, Kentish Snowman said:

Does it?!   The centre of the low pressure is still West of Ireland and there is still a ruddy great high pressure over Europe keeping them cold and blocked!

Bit like now really so no not Atlantic dominated in my book.....

Maybe our definitions of blocked are different!

I'd say the set up as it has been, and even today would still be blocked:

Rtavn001.gifRtavn0015.gif

No Atlantic train of lows, amplified meridional jet.

Now fast forward 10 days:

Rtavn2401.gifRtavn24015.gif

Atlantic full of low pressure once again, strong zonal W-E jet running across the Atlantic.

 

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
31 minutes ago, D.V.R said:

Very true but SM did say the ECM was correct last night and it's now reverted back.

Indeed. And it did quite a sudden flip to start showing the solution more favoured by UK coldies that it has just flipped back from. The models seem rather volatile at the moment. It was hubris for Steve Murr to call ECM correct last night, but it would have been hubris for anyone to do so in light of recent model output. In short, more chopping and changing still likely.

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
5 minutes ago, Paul_1978 said:

This thread :wallbash:...

Euphoria last night to doom and gloom in the space of 6 hours. You could let make it up..... 

People never learn.

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL

Not all doom and gloom though, we have a SSW or near as damn it about to happen which will help break up the PV and create some form of NH blocking, now we just need some luck that it helps us out by being in the right place. 

This block to our East has never been on the METOs radar to giving us anything properly cold, just a nagging S'Easterly which is now a little boring although plenty of frosts compared to the last few years.

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.

Just to illustrate the volatility in the model output. ECM showed temperatures in Warsaw trending to 7 degrees C next week on yesterday's 12z, now showing continued sub-zero spells with half the days remaining below freezing and and the other half with maxima of 1 degree. 

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire

I am a little surprised by this mini backtrack this morning. I certainly wasn't expecting it.  A very strange season indeed this year. Let's see what today's runs throw up. 

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
11 minutes ago, Ali1977 said:

Not all doom and gloom though, we have a SSW or near as damn it about to happen which will help break up the PV and create some form of NH blocking, now we just need some luck that it helps us out by being in the right place. 

This block to our East has never been on the METOs radar to giving us anything properly cold, just a nagging S'Easterly which is now a little boring although plenty of frosts compared to the last few years.

Here's hoping....my main worry is that the location of the SSW could just push the core of the vortex down towards us and just keep things unsettled. Very uncertain though.

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MOST OF THE MODELS SEEM TO BE SLIGHTLY OUT EVEN ON THEIR STARTING POSITIONS:

Further to my overnight post on the continuing strength of the Euro cold block (see page 312), I feel that the models mostly start off with the orientation of the HP cells (one centred around Germany and the over south-east Finland/north-west Russia) tilted slightly too much west-south-west to east-north-east. Both cells are more or less holding (as at 0800) their positions and slowly intensifying. This leads to a subtle but important difference with a very slightly more meridional tilt from south-west to north-east (this is particularly noticeable just north of Scandinavia). Whether this will all change by tomorrow is open to debate. If the HP can hold its ground (with the Finland/Russia HP aiding the more meridional pattern), this could lead to quite significant changes going forward. Again, to make my point, let's look at a range of cross model output from the 0z runs from their starting positions for T+0 (where available) or T+6 compared to the actual 0650 chart and the "live" pressure chart. All charts are from Meteoceil.

ACTUAL PRESSURE AT 0650 (1MB GRADIENTS)     "LIVE"  PRESSURE (1MB GRADIENTS)                      LINK TO ANIMATED ACTUAL PRESSURE CHART (to show the changes over the last 24 hours) 

       pression2_eur2-06.png                  pression2_eur2.png  http://www.meteociel.fr/observations-meteo/pression.php?region=eur2 (click "animation on 24" above, takes 10 seconds to load)

                    GFS T+6                                                             ECM T+0                                                MET OFFICE FAX T+6                                          GEM T+6                                                      NAVGEM T+6  

gfs-0-6.png         ECM1-0.GIF?25-12         20170125.0714.PPVA89.png         gem-0-6.png?00          navgem-0-6.png?25-05      

                     JMA T+6                                                          GEFS T+6                                               CMA (CHINA)T+6                                             WMC (MOSCOW) T+6      

J6-21.GIF?25-0        gens-0-1-0.png         cma-0-12.png?00          wmc-0-6.png

UKMO only start at T+72, so I have used their T+6 fax chart, which starts off being closest to the actual position compared to all the other models (but moves the Finland HP south-eastwards during today). GEM and NAVGEM both show a slightly more prominent second cell to the north-east but even they have it too far south. What will be an interesting comparison is to look for various model ensemble charts to see if they start off more like the actual position. Perhaps if there are any, then their early evolution might be rather different. I'll leave that to other posters as I've got a busy day ahead.

Edited by Guest
Correcting typos and to ensure that all the links and charts work properly.
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Posted
  • Location: Alvechurch 8 miles South West of Birmingham
  • Weather Preferences: Snow
  • Location: Alvechurch 8 miles South West of Birmingham
33 minutes ago, Paul_1978 said:

This thread :wallbash:...

Euphoria last night to doom and gloom in the space of 6 hours. You couldn't make it up..... 

Absolutely Paul  I think if a lot of people in here seen in print that Elvis would arise from the dead in 240 they would believe it lmao

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

Well that lasted long! Back to square one this morning, the ECM ensembles have dropped the colder cluster and its back to mediocrity, the PV split on the 00hrs run doesn't last long and as soon as the Siberian lobe starts heading west this feeds the Canadian one which powers up the Atlantic.

Unless you have a decent block to the north/ne then a flimsy ridge is no match. The earlier timeframe is crucial to whether you stand a chance and it all goes pearshaped quite early.

Give it to tonight to see if there might be another change but its not really good to see last nights potential dropped so quickly. Its quite typical that as soon as the GFS started inching towards the Euros they backtracked.

 

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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
8 minutes ago, nick sussex said:

Well that lasted long! Back to square one this morning, the ECM ensembles have dropped the colder cluster and its back to mediocrity, the PV split on the 00hrs run doesn't last long and as soon as the Siberian lobe starts heading west this feeds the Canadian one which powers up the Atlantic.

Unless you have a decent block to the north/ne then a flimsy ridge is no match. The earlier timeframe is crucial to whether you stand a chance and it all goes pearshaped quite early.

Give it to tonight to see if there might be another change but its not really good to see last nights potential dropped so quickly. Its quite typical that as soon as the GFS started inching towards the Euros they backtracked.

 

Not really because I never thought for one minute that things will run exactly like it said last night, I see this morning the same theme just different variations of it. 

Also remembering the fact that the 0z for some reason are far more less amplified than the 12z. Not surewhy but this is the pattern of the winter so far

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire
9 minutes ago, nick sussex said:

Well that lasted long! Back to square one this morning, the ECM ensembles have dropped the colder cluster and its back to mediocrity, the PV split on the 00hrs run doesn't last long and as soon as the Siberian lobe starts heading west this feeds the Canadian one which powers up the Atlantic.

Unless you have a decent block to the north/ne then a flimsy ridge is no match. The earlier timeframe is crucial to whether you stand a chance and it all goes pearshaped quite early.

Give it to tonight to see if there might be another change but its not really good to see last nights potential dropped so quickly. Its quite typical that as soon as the GFS started inching towards the Euros they backtracked.

 

The massive change in the model output yesterday morning took me by surprise as this typically doesn't happen by the likes of the UKMO/ECM within the reliable timeframe. So my theory is either the model output is volatile or some issue with the starting data yesterday.

Whichever it is, the past 24hrs only highlights you cannot make bold statements based on a set of runs whether you are calling mild or cold. This is why I try not to react too quickly by making comments such as "BOOM".

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .
1 minute ago, Severe Siberian icy blast said:

Not really because I never thought for one minute that things will run exactly like it said last night, I see this morning the same theme just different variations of it.

Also remembering the fact that the 0z for some reason are far more less amplified than the 12z. Not surewhy but this is the pattern of the winter so far

It maybe the same overall theme initially but the NH picture later on the 00hrs ECM compared to the last nights 12hrs is different. I never trust outputs at longer range to maintain a PV split, in recent years these have been a false dawn.

In terms of morning outputs being less amplified I'd agree for some reason that's been an issue this winter. I think its clear that unless you have a good start with enough energy going se'wards then any ridge to the ne will never be able to force enough trough disruption to fight off the next bout of Atlantic energy.

 

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
32 minutes ago, Summer Sun said:

UKMO extended shows winds coming up from the southwest

ukm2.2017020100.168.lant.troplant.prp.fcst.gentracker.png

Always driest the further south and SE you are

Hello Mr Azores high!

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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
28 minutes ago, Summer Sun said:

UKMO extended shows winds coming up from the southwest

ukm2.2017020100.168.lant.troplant.prp.fcst.gentracker.png

Always driest the further south and SE you are

In contrast at the same time the ECM high res , shows backing of the flow across the British Isles as the  lows and zonal flow push into Euroland below 50N , very similar to what shorter term model from ARPOPeu was indicating. Still a lot of uncertainty in the models of how to dislodge the Euro cold block.

 C

ecm2.2017020100.168.lant.troplant.prp.fcst.gentracker.png

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

A little more energy going se at T132hrs. You need to see the weakest possible low pressure to the west, the more the low deepens there the more ne the energy will want to go. To the north the sooner the PV can split the better.

Earlier its a bit messy, you need the low over the UK to fill as quickly as possible and clear e/se and have clear distance between itself and the upstream troughing, no shortwave energy hangback because that acts like a tow to the trough upstream.

The GFS tries but too much energy upstream and theres no way with the PV lobe in Canada and such a weak ridge to the north that you can get enough trough disruption.

Edited by nick sussex
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Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

a nice little wedge to our north on the 6z we just need the Atlantic to dig a little further south

IMG_1815.PNG

This period is open to change as the differences between the 00z v 12z ECM highlights.

 

 

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Posted
  • Location: bingley,west yorks. 100 asl
  • Location: bingley,west yorks. 100 asl

Ecm=ott regards amplified solutions.

Gfs=Nearly always to flat and progressive and slowly backtracks.

Ukmo=always seems to be somewhere in between. And seems to be correct more.

It's been a frustrating one alright but cold solutions never been backed by Exeter and they've been pretty good in short to medium term.

Edited by joggs
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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

The 6z is another wind and rain fest, with some fairly deep low pressure systems moving across. On to the 12z.

 

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

Essentially the big problem is the PV lobe in Canada, you'll never get enough amplification upstream at the key timeframe to drive enough energy se'wards. Unless that lobe gets pulled much further west nw then I think we're chasing shadows. To battle that PV lobe you'd need a much strong block to the ne and not a weak ridge.

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