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Model Output Discussion - 23rd Jan - 12z onwards


Paul

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Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

Hang on a minute !! Wasn't GS5 and Mogreps showing a strong signal for a blocked pattern 10 days ago ? Very strong signal I seem to remember for mid feb. Goes to show that it's not always right.

 

I think the remark was more about the lack of any negative height anomalies over the Europe view on ECM32 but uncertainty on what form this might evolve into. People made their own assumptions to suit the desire - can cause a lot of confusion to the casual reader!

JMA monthly ensemble, for what it is worth, they are in agreement on a large anticyclonic area for W Europe, week 3-4.

 

Y201501.D2812.png

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

This winter like last has always had low heights to the nw and i dont care what anyone says,that scuppers our chances of deep cold a hell of alot more than not.Also a bitter ne america the same,it just fuels the jet.All these positive background signals have not been able to overide this for some reason.Bring on the solar min and cold amo.As a side note joe bastardi say americas next3/4 out of 5 winters will be mild(througg his reasonings).Bring it on for me.

I also remember our feb 91 beasterly coincided with record breaking warm temps in ne U.S.

The meto have been on the money nearly all winter.

Edited by joggs
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Posted
  • Location: North Somerset, UK
  • Location: North Somerset, UK

Yes but the blocking position was not mentioned, because it was unknown.

Moreover: read way back and you'll see it called for greater likelihood of anticyclonic influence close to UK but you'll find my post noting that wasn't necessarily "blocking per se". At no point have UKMO indicated any *strong* signal for true northern blocking this winter and that remains the case looking ahead (with EC Monthly offering some support to broad signals from latest GS5 ensembles mid-later Feb).

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Posted
  • Location: East Anglia
  • Location: East Anglia

Mushy speaks a lot of sense there but WIB I don't think so his prognosis was an end by the start of the week. The truth is the weather makes monkeys of us all, and as I said earlier a week is a long time in synoptic evolutions that's why we keep coming back. In truth if the day ever comes where the models get much better at predicting beyond a couple of days, say 5 or 7, then that will be the day when threads like this will die.

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Posted
  • Location: Wirral, Merseyside
  • Weather Preferences: Snow & Thunderstorms
  • Location: Wirral, Merseyside

More snow possibilities moving south over the weekend

 

 

post-23289-0-91456300-1422614898_thumb.p

post-23289-0-88857500-1422614905_thumb.p

post-23289-0-93267600-1422614916_thumb.p

post-23289-0-71369300-1422614922_thumb.p

post-23289-0-97886700-1422614926_thumb.p

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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

On that chart it seems that the whole Atlantic is high pressure with 2 big cells.

Also you could say the Azores high is replaced with a low pressure of 1010.

That second ridge is a nuisance as it will result in the high over the UK ridging into Scandinavia to retrograde westwards which cuts the cold feed off. Ultimately the easterly is still up for grabs and is highly dependent on how far north east the high can initially build and hence how far west can the cold pool over Europe back. Small changes there could be the difference from a quick breakdown to westerlies and a pattern which remains cold for the next 10 days plus.

Given we have deep low heights over Europe, I would certainly question any persistent zonal signal. As the previous mild spell lasted a full 3 days, I have to admit that I did fall for that zonal signal so this time I am not going for it (at least not for an extended period anyway).

 

For what it is worth, the Navgem also has an east/north easterly developing from midweek

navgem-0-144.png?30-11

Edited by Captain shortwave
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Posted
  • Location: South Croydon
  • Location: South Croydon

There seems to be a pattern here. The 0z runs seem to try to flatten, whereas all other runs for the day seem to re-amplify the pattern.

Yes it does seem to have been a pattern over the last few days.  Let's see if it repeats.

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Posted
  • Location: nr Guildford, surrey
  • Location: nr Guildford, surrey

There seems to be a pattern here. The 0z runs seem to try to flatten, whereas all other runs for the day seem to re-amplify the pattern.

It's a familiar pattern with many a cold spell modelling. The 0z tend to be shall we say 'glass half empty' a lot of the time

Have to look at it really as a 24 hour comparison between runs rather than what it compares with to the 18z GFS.

As for the longer range outlook, now these are guidelines and signals and the chaos theory being what it is, those are subject to change. At the monent though this is shaping up to be a longer and somewhat colder version of the last cold spell. Instincts tell me this may repeat at least one more time before winter is out with variations around the theme. Has been hinted at a few times in the output. As has a high sitting over or close to the UK with cold nights. Could be a frosty month

Then we enter spring and then I think high pressure to the south becomes more to people's liking ;)

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Posted
  • Location: Bude
  • Weather Preferences: Extreme weather...heavy snow and heat waves
  • Location: Bude

More snow possibilities moving south over the weekend

That's better, looking at the here and now and the good cold spell we are in rather worrying what's coming next.

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

The GFS 06hrs run shows another variation on the same theme regarding an easterly flow into the UK but still too far out to have confidence in.

 

These inter run differences in high position make it very difficult to forecast for the latter half of next week and theres also uncertainty with low pressure exiting ne Canada.

 

My next shortwave obsession is now underway! for those that suffered endless posts re the other shortwave which I criticized the ECM and GFS over this next one is here:

 

post-1206-0-36144000-1422614785_thumb.pn

 

Think of this shortwave as your anti-clockwise motion on a clock, as this heads across Canada and engages the PV it will edge low heights to the north east more ne rather than east.

 

You need to see this as amplified as possible, if you're not on the NH angle have a look at this anti-clockwise motion, start out at T114hrs and go through to see how the energy moves. The UKMO does not have this more developed shortwave but a flatter weak feature, the ECM  complicates matters by leaving this low in the Atlantic too far north which stops a high pressure lobe from  developing more ahead of that shortwave, its upstream shortwave is also flatter:

 

post-1206-0-76273600-1422615439_thumb.gi

 

Because of these differences and uncertainties upstream you can make a case for several different scenarios towards the latter part of next week.

Edited by nick sussex
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Posted
  • Location: Milltimber, Aberdeen ~ 80m asl
  • Location: Milltimber, Aberdeen ~ 80m asl

It appears all models are picking up a general signal for flattening the pattern, although the key to this outcome lies in what happens over N. America circa T96 – T120. Given this is at the limit of model ‘accuracy’, it would only take a slight amplification to result in energy being sent south rather than east - even if this delays the westerly onslaught it would be good as it buys more time for pressure to build over Scandi. At the same time, the ridge extension from the Russian/Arctic high could be being underplayed too. Both are long shots, but we shouldn't dismiss anything just yet, although granted, odds currently favour a switch to a more zonal  pattern. Without the assistance of high level blocking (lacking all winter!), the Atlantic ridge was always going to be temporary affair. If there is to be any slight increase in upstream amplification, we better hope this starts getting reflected in the ensemble data ASAP.  

Edited by Altostratus
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Posted
  • Location: Wirral, Merseyside
  • Weather Preferences: Snow & Thunderstorms
  • Location: Wirral, Merseyside

The GFS 06hrs run shows another variation on the same theme regarding an easterly flow into the UK but still too far out to have confidence in.

 

These inter run differences in high position make it very difficult to forecast for the latter half of next week and theres also uncertainty with low pressure exiting ne Canada.

 

My next shortwave obsession is now underway! for those that suffered endless posts re the other shortwave which I criticized the ECM and GFS over this next one is here:

 

attachicon.gifgfsnh-0-120.png

 

Think of this shortwave as your anti-clockwise motion on a clock, as this heads across Canada and engages the PV it will edge low heights to the north east more ne rather than east.

 

You need to see this as amplified as possible, if you're not on the NH angle have a look at this anti-clockwise motion, start out at T114hrs and go through to see how the energy moves. The UKMO does not have this more developed shortwave but a flatter weak feature, the ECM  complicates matters by leaving this low in the Atlantic too far north which stops a high pressure lobe from  developing more ahead of that shortwave, its upstream shortwave is also flatter:

 

attachicon.gifECH1-144.gif

 

Because of these differences and uncertainties upstream you can make a case for several different scenarios towards the latter part of next week.

This is a good thing then as the cold may well continue further.

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

The ECM ensemble spread at T144hrs, :whistling:

 

post-1206-0-10136000-1422616635_thumb.gi

 

The latest from the NCEP state forecast for Michigan:

 

TUE-THU...MEDIUM RANGE GUIDANCE IS TRENDING STRONGER WITH THE NEXT
SHORTWAVE DIVING SE OUT OF CANADA FOR THE MIDDLE OF THE WEEK. LOOKS
LIKE THERE MAY BE THE POTENTIAL FOR WIDESPREAD -SN ACROSS THE FCST
AREA TUE/TUE NIGHT ASSOC WITH THE SHORTWAVE ALONG WITH A PERIOD OF
MORE SIGNIFICANT LAKE ENHANCEMENT NEAR LAKE SUPERIOR. BEHIND THE
SHORTWAVE...MODELS INDICATE A VERY COLD SURGE OF ARCTIC AIR WITH
850MB TEMPS OF -25 TO -30C MOVING OVER THE AREA WED INTO EARLY THU.
 

 

 

 

 

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Posted
  • Location: leicester
  • Location: leicester

The ECM ensemble spread at T144hrs, :whistling:

 

attachicon.gifEEH1-144.gif

 

The latest from the NCEP state forecast for Michigan:

 

TUE-THU...MEDIUM RANGE GUIDANCE IS TRENDING STRONGER WITH THE NEXT

SHORTWAVE DIVING SE OUT OF CANADA FOR THE MIDDLE OF THE WEEK. LOOKS

LIKE THERE MAY BE THE POTENTIAL FOR WIDESPREAD -SN ACROSS THE FCST

AREA TUE/TUE NIGHT ASSOC WITH THE SHORTWAVE ALONG WITH A PERIOD OF

MORE SIGNIFICANT LAKE ENHANCEMENT NEAR LAKE SUPERIOR. BEHIND THE

SHORTWAVE...MODELS INDICATE A VERY COLD SURGE OF ARCTIC AIR WITH

850MB TEMPS OF -25 TO -30C MOVING OVER THE AREA WED INTO EARLY THU.

what does all that mean?
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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

Im shocked too at that signal. we dont know how strong it is though, as 'signs' doesnt sound very convincing. Hope it fades.

 

When we have fantastic posts on here from Tamara for example, giving a very convincing argument for a 'good' February through providing a very detailed report on background signals then this signal seems to go against everything. It sounded like everything was in our favour reading her brilliant posts.

 

Cold looks locked in until Friday anyway, plenty of -8 850s around from Sunday onwards and models do show features and kinks in the isobars so is not all doom and gloom :)

But WC, that's been the point...none of them have come to fruition.  No matter how detailed or good they are, the good signs have always thus far been overridden, shame as some of the thought process has been very convincing [indeed at one point around Xmas it looked like Ed and Tony played a blinder but something scuppered it likewise Cohen].  Been the story of this winter thus far slapping many in the face [i was slapped in early Dec ]....until now when it has played ball.

I Fs update in short term is quite a good outlook for next week, so lets have that first and see what is shown come Tues/Wed?

 

BFTP

Edited by BLAST FROM THE PAST
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

what does all that mean?

The spread shows a possibility of a deeper shortwave digging further south into the USA, so something a bit more like the GFS 06hrs run.

 

The NCEP update thinks something deeper is more likely, we're in a similar position to a few days back with the shortwave exiting the eastern USA, the flat solution shown in a few runs by the GFS and ECM was less favourable down stream for the UK so we have to hope that the models do a repeat performance by amplifying the upstream flow a bit more.

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Posted
  • Location: King’s Lynn, Norfolk.
  • Weather Preferences: Hot and Thundery, Cold and Snowy
  • Location: King’s Lynn, Norfolk.

This winter like last has always had low heights to the nw and i dont care what anyone says,that scuppers our chances of deep cold a hell of alot more than not.Also a bitter ne america the same,it just fuels the jet.All these positive background signals have not been able to overide this for some reason.Bring on the solar min and cold amo.As a side note joe laminate floori say americas next3/4 out of 5 winters will be mild(througg his reasonings).Bring it on for me.

I also remember our feb 91 beasterly coincided with record breaking warm temps in ne U.S.

The meto have been on the money nearly all winter.

Isn't always the case just because America is cold we end up warm. The NE quadrant of America is always going to be massively cold due to the PV being directly aimed at them all the time and a massive fetch across icy lands from the West and North (Predominant wind direction). I'm sure some of the notorious UK winters still happened with the cold over the NE US. 

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Posted
  • Location: Morden, Surrey.
  • Location: Morden, Surrey.

But WC, that's been the point...none of them have come to fruition.  No matter how detailed or good they are, the good signs have always thus far been overridden, shame as some of the thought process has been convincing.  Been the story of this winter thus far slapping many in the face.

I Fs update in short term is quite a good outlook for next week, so lets have that first and see what is shown come Tues/Wed?

 

BFTP

Agree wholeheartedly,

As i stated a few months ago you can have all the background signals pointing in a favorably however i get the feeling that most on here think it leads us automatically into a colder outlook which as i previously stated it doesn't. It's just another piece to a big puzzle.

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

Im shocked too at that signal. we dont know how strong it is though, as 'signs' doesnt sound very convincing. Hope it fades.

 

When we have fantastic posts on here from Tamara for example, giving a very convincing argument for a 'good' February through providing a very detailed report on background signals then this signal seems to go against everything. It sounded like everything was in our favour reading her brilliant posts.

 

Cold looks locked in until Friday anyway, plenty of -8 850s around from Sunday onwards and models do show features and kinks in the isobars so is not all doom and gloom :)

 

Yes it has been a very interesting spell of weather with thunder, snow, sleet, wind chill, hail, etc. The usual suspects have had the main snow coverings and for the south in this type of setup it is nearly always more miss than hit. The NH profile was never going to convince for more than the repeated pattern of a transient meridional flow, with the PV continuing to show mobility due to the Pacific Ridging ,as per this whole winter showing no longevity. So we have made the most of an average set up.

 

There is no reason to suggest that the current winter pattern will not remain the driving force for the next 6 weeks, we have seen last winter that the entrenchment of the pattern can be hard to shift. However as we enter Feb the PV will be less resilient and with the residue cold pools left over (S Europe) from this current spell I suspect the holding pattern till the next Pacific/Alaskan Ridge development may favour us for a more seasonal spell; positive pressure anomaly affecting the UK (UK high, Azores or heights to the NE/E) this time rather than zonal:

 

Clusters 06z run at D14: post-14819-0-88597600-1422620789_thumb.p

 

Where the next wave pattern will set up may dictate the next potential cold spell. The JMA suggests the Pacific Ridge will be further east:

 

post-14819-0-30968600-1422613846_thumb.p

 

The cold pool in the US and the sympathetic ridge now over the UK rather than the Atlantic. Early days for details but JMA certainly showing a continuation of this winter's over riding signal. Despite all the positive winter variables it is clear that these have so far played second fiddle. No Major SSW is likely (latest blog from Dr Cohen does not even hint at that now: https://www.aer.com/science-research/climate-weather/arctic-oscillation) and in reality the NH cold has been driven by the repeated Pacific amplification and the Rossby wave downstream effect followed by the regrouping of the PV.

 

The cold upper flow looks to continue till next weekend but apart from Monday-Tuesday (maybe Sunday am) a good snowy spell is not on the cards as Wednesday onwards we have the sinking ridge, cold but less showery. The Atlantic low forecast for Monday looks like being too far west to effect the UK and the disturbance in the subsequent Arctic flow looks like it is also going to be favouring the far west on current projections (time for change). Forecast max temps for the next five days for my area are 7,6,6,5 & 5C so just below average and the wind chill is the most memorable factor in this current spell in my backyard:

 

Atlantic low mean: post-14819-0-72781200-1422620337_thumb.p  Cold uppers next 8 days at least:post-14819-0-36339900-1422620337_thumb.g

Edited by IDO
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Posted
  • Location: Nr Malton, North Yorkshire 53m
  • Weather Preferences: Snow/Thunderstorms
  • Location: Nr Malton, North Yorkshire 53m

Looking at all 21 runs available from GFS/GEFS on the panel maps, 9 out of 21 at 168 still show what I would call a decent easterly. By decent I mean potential for snow, especially along the east coast. All charts look cold...

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=168

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Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby

Have to agree I see no Easterly, I see maybe more Disruption to the Atlantic for a short while longer but I think the writting is on the walls that in 7-10 days time the Atlantic will roll in with High Pressure to the south as per the charts you have posted..... not the end of winter by any means but it will give those who want a bit of warmth something to cheer.

As for who called this spell correct..... Firstly lets wait until after its over Its easy to claim someone is right before the event, especially when the same cliam is made every day...... Like Shooting Fish in a barrel unfortunately no one has made a hit yet.

 

bib.... well no one can actually say that. but IF the current gfs projections for mid feb verify, then tbh i wouldnt have thought another cold spell with snow potential (for longer then 3 days) would be very unlikely .

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Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby

A breakdown in 7/8 days time is a bit of brave man FI scenario to call isn`t it?

 

 

not really, theres pretty good agreement , its shown currently on the models, so whilst might not happen its fair game for comment.

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