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Model Output Discussion - A cold start to Spring?


Message added by Paul,

Please keep your posts to discussing the model output in this thread, and for more general winter weather chat please use the Spring chat, moans and ramps thread.

The model highlights thread is also available for a more concise view of the model discussions. 

Be kind -- Stay on topic -- Share your knowledge -- Be polite -- Be honest -- Be tolerant -- Be family-friendly

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Posted
  • Location: Epsom, Surrey, 100 Meters above sea level
  • Weather Preferences: Anything Extreme
  • Location: Epsom, Surrey, 100 Meters above sea level
30 minutes ago, Mark wheeler said:

Much more scatter returning on this morning's mogreps .

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That's thrown a spanner in the works combined with the post below yours re return to westerlies. is this going to end up a 2 day cold blip before were waving goodbye to this season ? 

I hope not

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Posted
  • Location: Evesham/ Tewkesbury
  • Weather Preferences: Enjoy the weather, you can't take it with you 😎
  • Location: Evesham/ Tewkesbury
11 hours ago, ANYWEATHER said:

Gfs always on a bender, Ecm showing the trend for the Atlantic to win......😨

Slow ,but sure trend that the Atlantic is going to wake up after a very quiet spell, it will probably be around mid- March before it really starts to kick in, ...😯

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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
10 minutes ago, Tim Bland said:

Possibly,  but all looks a Bit marginal to me, even areas further north that see falling snow will find it struggles to settle if these latest runs are near the mark

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Could go either way, might well end up too marginal. Need that LP to move East or ESE into the colder air and maintain intensity or deepen, with the colder air digging back south. 

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Posted
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast
  • Weather Preferences: Severe Storms and Snow
  • Location: Home near Sellindge, 80m/250feet, 5miles from Coast

One of these days I'm going to wake up in the morning and the models will be exactly the same as when I went to bed :drunk-emoji:

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
2 minutes ago, DiagonalRedLine said:

Is one of those continued situations from the models where it’s worth giving them more time as to how they develop the blocking patterns. The MJO, SSW, migration East of the Vortex and such. All having an impact on the sorting out of the pattern. Because…

…is really the case, currently. 

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Yes, I think so.  I think an important factor is how much deep cold we get in, and that might be ironed out quite quickly.  After that we know from experience that it can be harder to shift than the models think.  

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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

Is it really that difficult to get a half decent North Easterly in early March these days?Could contain: Chart, Plot, Outdoors, Nature, Map, Sea, Water, Atlas, Diagram, Person

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Modelling is beginning to hone in on the broader outcome now as high-lat blocking returns to the scene across the board following some brief disruption from tropical storm Freddie "muting" tropical forcing. 

The 4th - 9th March appears to be the window of opportunity for cold albeit nothing exceptional is currently being shown really, temperatures look to be about where they are now. Indeed, the signal for this has been there for a fair number of days now, the below is taken from my post on the 17th:

Quote

 

Favourable MJO triggering a rise in AAM with an SSW occurring aloft. In theory this all suggests an increased likelihood of high latitude blocking as we progress into early March. 

One fly in the ointment is the continued lack of consistent poleward flux being modelled, equatorward flux looks to continue for the time being, this essentially blocks the initial warming from downwelling & impacting the troposphere.

 

And;

Quote

 

The second round of warming towards the end of this month will likely deliver the final blow, in conjunction with rising AAM in response to the recent MJO phasing & subsequent rise in +FT & probably then +MT timing will be perhaps better for more favourable downwelling of the -ve anomalies from the stratosphere into the troposphere. 

I'd not be surprised to see signs of blocking finally making it into the Greenland locale by the 2nd week of March & this then would bring the potential for a deeper cold spell of weather, albeit with increasingly diminishing returns as the days grow longer & the suns strength grows ever longer. The further into March we go the more "perfect" we need the synoptic pattern to deliver widespread low levelsnowfall.

 

10 days on and the signal, after a lot of noise within NWP modelling is back on track. High pressure will attempt to retrogress towards Geeenland drawing in northerly winds, there remains considerably uncertainty on "how cold" it'll get but throughout this entire saga there's been a very limited/weak signal for deeper cold with widespread low-level snow potential and that remains the case today. 

Below average, yes. But notable/exceptional? Unlikely. 

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Posted
  • Location: North east Hampshire
  • Location: North east Hampshire
29 minutes ago, bluearmy said:

Isn’t metcheck just the gefs control to day 15 ? 
I could ask my eleven y o to draw some weather pictures if that’s peoples’s base point !

 

 

It’s a bit of a tongue in cheek ‘in’ joke that’s based on some posts from yesterday afternoon. If you missed them you won’t know what it’s all about!

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

A better upstream pattern at day 5 on the ICON 06 hrs run compared to the earlier 00hrs run. 

The shortwave exiting the ne USA should phase at the bottom of that more favourable  troughing  . The anti clockwise effect that causes should angle the trough negatively tilted so helping with WAA.

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We could do with some energy disrupting east se to support the block .

 

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Posted
  • Location: Welwyn Garden City
  • Weather Preferences: Seasonal and interesting weather including summer storms and winter snow
  • Location: Welwyn Garden City
3 minutes ago, Met4Cast said:

Modelling is beginning to hone in on the broader outcome now as high-lat blocking returns to the scene across the board following some brief disruption from tropical storm Freddie "muting" tropical forcing. 

The 4th - 9th March appears to be the window of opportunity for cold albeit nothing exceptional is currently being shown really, temperatures look to be about where they are now. Indeed, the signal for this has been there for a fair number of days now, the below is taken from my post on the 17th:

And;

10 days on and the signal, after a lot of noise within NWP modelling is back on track. High pressure will attempt to retrogress towards Geeenland drawing in northerly winds, there remains considerably uncertainty on "how cold" it'll get but throughout this entire saga there's been a very limited/weak signal for deeper cold with widespread low-level snow potential and that remains the case today. 

Below average, yes. But notable/exceptional? Unlikely. 

Yes have noticed for a while now the trend for the colder clustering between 4th & 9th..

ens_image-2023-02-27T091553_585.thumb.png.583f14e228d46221b6a71ea0c83a963d.png

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..with the signal for a rise in temp following...however with this now happening..

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...plenty of uncertainty still to be played out i think..as somebody said above it would be nice to have a bit of continuity on the ops...it gets to a point where i almost dred looking at the next run...note 'almost'..🤣

 

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

Oddly the pattern after day 10 probably has higher confidence than the days preceding this. Purely because the outcome of successful retrogression eventually ends in the same position as the pattern where the Azores high ridges in early on in week 2 The retrogression looks swift as conditions will quickly become more west based -NAO and eventually see low heights return to our north west. A west to south westerly flow will return at some point, it is more a case of seeing whether we can get a northerly flow across the U.K. for a time.

I will say that there is a good chance of a quite potent northerly occurring, especially with the polar vortex relocating to our north east.

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

These charts do not support the ECMs version .... the ECM is relying on the breakdown of the ridge to our West allowing a southerly tracking jet.

IMHO the GFS 00z is likely to be closer to the solution.

 

610day.03.gif

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Just a quick update on the current state of the teleconnections: 

The strongest +EAMT event of the winter is currently occurring with +MT quite literally off the charts at the moment following sustained MJO activity in the Pacific.

 gltaum.90day.thumb.png.28aea063a502a76da49c8d15fb03af43.png

The AAM as expected has continued to rise though I suspect we'll see quite a large drive into +ve territory over the coming days/next week on the back of the strong +EAMT event.

gltotaam_sig.90day.thumb.png.b1bfea82e31ad64cced960743fd19d6f.png

We've got a more coherent MJO signal on the RMM plots following disruption from Freddie with phase 7 transitioning into phase 8 through March. There is no phase 8 Nina composite but given the likely sustained +AAM the atmosphere will be more nino-esq;

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The composite for that is quite frankly a mess so it's difficult to ascertain any clear progress through March using the MJO alone, but using the the GSDM/GWO & of course factoring in the MJO & various other drivers not mentioned I will attempt a prediction for March.

1st - 10th:

Temperatures likely to be below average with blocking extending northwards into Greenland during this cold period. The coldest anomalies likely to be 4th - 9th. Too early for specific details re: snow but my gut feeling is it wont be widespread, but there might be some around from little features assuming HP moves far enough away from the UK to allow for an unstable airflow. Nothing notable or exceptional.

10th - 20th:

Seasonal wavelength changes & transition into phase 8 of the MJO will mean an increasing influence from the Azores high, though i'd be wary of any NWP models currently showing a more progressive, zonal pattern in the extended, they are likely far too quick to remove the negative anomalies from Greenland, although a west based -NAO is a possibility, especially later into the period. The jet gradually moving back north during this period may enhance the potential for battleground snowfall, particularly early on in this period. 

I'll revisit this prediction in a couple of weeks, but to summarise;

  • High latitude blocking increasingly likely early March 
  • Too early to be certain of any cold risks across the UK, particularly where "deep cold" is concerned
  • Block placement will be critical
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Posted
  • Location: Dorset
  • Weather Preferences: Warm and dry, or very cold. See my profile for model trivia
  • Location: Dorset
2 minutes ago, mushymanrob said:

These charts do not support the ECMs version .... the ECM is relying on the breakdown of the ridge to our West allowing a southerly tracking jet.

IMHO the GFS 00z is likely to be closer to the solution.

 

610day.03.gif

I have been wary of these charts when they are issued on Saturday and Sunday since I learned from another member that the automated weekend blend is always the same blend of the GFS and GEM ensemble means and doesn't include the EPS (which is invariably chosen as a significant component of the blend by the human forecaster on weekdays)... what are your thoughts on this?

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Posted
  • Location: redcar,cleveland
  • Weather Preferences: Winter cold,snow and frost. Summer hot and thundery
  • Location: redcar,cleveland

Much better Atlantic profile more energy going under the ridge 

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Posted
  • Location: Guisborough
  • Location: Guisborough
Just now, seabreeze86 said:

Much better Atlantic profile more energy going under the ridge 

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Seabreeze, if it comes off then we are in the sweet spot this time around 

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Posted
  • Location: Hull
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Hull

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A lot better from the GFS here, also for those who like polar lows, there is one just to the north of Finland.

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Is today the day the second SSW is occuring? May be wrong here, but perhaps no surprise it also marks the start of the point where the models should begin to pick up likely effects of the first SSW imprinting and with expected quicker effect from the second this will also be thrown into the mix - but also makes for added complexity and chaos.

Unike last week which was a case of waiting whilst the dry cycle on the tumble dryer does its thing, we are entering a much more exciting period model watching wise, the models should in theory be less prone to marked variance run to run (GFS excluded - as its forte).

This morning we are seeing a more definate influence from the Polar Vortex shifing to the Asian side - this is the major force, not the atlantic I may add - it will dictate the behaviour of the atlantic and where heighs currently sat over the UK migrate. UKMO shifts these heights NW as the PV embeds itself just to our east, the atlantic low has nowhere to go but either under or disrupts, ECM going the same way. 

Reading some posts this morning about lack of cold to produce snow, as mentioned whether snow falls and sticks depends on many many factors not just 850 mb temps which incidentally to me look conducive to snow to modest levels away from the south at least. Evaporative cooling is perhaps the biggest factor and that's always a nowcast factor. 

 

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Posted
  • Location: redcar,cleveland
  • Weather Preferences: Winter cold,snow and frost. Summer hot and thundery
  • Location: redcar,cleveland
Just now, Gizzy said:

Seabreeze, if it comes off then we are in the sweet spot this time around 

We sure are ,still plenty of hurdles to jump yet though but the trend is good at the minute 

look at the difference a small adjustment west make 

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Posted
  • Location: West Dorset
  • Weather Preferences: Warm summers, Snowy winters.
  • Location: West Dorset

Talk of cross polar ridging yesterday. You can see this attempt easily with the jet.

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Posted
  • Location: Banbury
  • Weather Preferences: Deep Deep Snow causing chaos
  • Location: Banbury
49 minutes ago, Drifter said:

It’s a bit of a tongue in cheek ‘in’ joke that’s based on some posts from yesterday afternoon. If you missed them you won’t know what it’s all about!

Thank you - thought I would have to get crayons out .................meanwhile the 6z is ok

gfsnh-0-168.png?6

A week today 

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Posted
  • Location: Epsom, Surrey, 100 Meters above sea level
  • Weather Preferences: Anything Extreme
  • Location: Epsom, Surrey, 100 Meters above sea level

interesting chart at +174 and an improvement on the 00z.

Were obviously looking both NE, N and W and hoping that the pieces allign just right.

Too many obstacles in the way for my liking prior to this to overcome, but its dragging its heels towards the semi reliable timframe now.

Just seems to me that weve spent a whole week looking at more or less the same chart but what I am liking is that the models picked up on this way into FI and have pretty much ran with it all the way through.

6th-8th March has pretty much always been the date of arrival.

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