Model Output Discussion 1200 hrs 30/09/14

[phil nw.]

A couple of of posts have been removed-no model discussion in them.

 

A reminder to all as anticipation builds for our first dose of colder weather just to keep to the model outputs in here please.

 

If anyone wants to ramp,moan or speculate without some reference to charts then the other model thread is the place to go-

https://forum.netweather.tv/topic/81281-model-banter-moans-and-ramps-autumnwinter-2014/

 

Ok on with discussion.

[shaky]

http://modeles.meteociel.fr/modeles/gfs/runs/2014102912/gfs-0-138.png?12

 

At last.....

 

Snow for the North & Possibly Ireland ( N)

steve do you think there's any background signals that are driving this change to colder weather!!!cos to be fair a change like this to happen so rapidly is not normal!!!its taken just 24 hours for all the models to agree on this northerly!!

[Summer Sun]

Something for our snow starved fans to enjoy this afternoon

 

 

Even if the snow shown is restricted to higher ground its shown to be darn cold for a lot

 

 

:cold:

[SMU]

steve do you think there's any background signals that are driving this change to colder weather!!!cos to be fair a change like this to happen so rapidly is not normal!!!its taken just 24 hours for all the models to agree on this northerly!!

 

You could consider that a Northerly in November is standard fair, so nothing exceptional, the main context of November will hapefully be the continued fragmentation of the polar Vortex,

 

In November we will see LARGE areas of low hights over the Northern Hemisphere, more so than Oct, so if all that is squashed over in Eurasia OR Split into europe / America with periods of blocking ( shallow or moderate ) over the pole-

 

that will be good news-

 

S

[IDO]

Looking at the GFS ensembles for around D6 the op is nearly the coolest of its whole suite:

So the op at the moment is the worse case scenario. Only more runs will tell if it's an outlier. Though from experience I would be confident it was. Though no denying it is turning cooler from next week for a few days.

Before that the two fronts crossing west to east over the weekend looks like the first will just bring cloud & drizzle to the SE/E and the second will be less potent than when it arrived in the west and possibly patchy. Both look like mainly overnight events.

Edited October 29, 2014 by i'm dreaming of...

[knocker]

Now that's one heck of a northerly that! Straight from the pole!!

 

And move on a couple of days and that's one heck of a south westerly straight from Canada.

[knocker]

A reversal to Atlantic driven wet and windy? Surely not.

 

[shaky]

And move on a couple of days and that's one heck of a south westerly straight from Canada.

which will hopefully and probably be gone in the next run!!from a coldies perspective I would love to see a cold chart at 216 hours from the ecm tonight!!

[MR EXTREMES]

wow nice seeing lower heights into europe gefs good run the gem just explodes into life most interesting charts since 09/10 already!.

still a long way to go but blocking looks like its trying for a cold shot.

[MR EXTREMES]

A reversal to Atlantic driven wet and windy? Surely not.

of coarse its going to be wet and windy.

but snow in the north and much cooler here in the south all models are in agreement that there will be a cooler type moving forwards into nov also jet going south and possibility of early cold spell perhaps setting up for winter 09/10 round 2

[Polar Maritime]

And no off topic one liners please..

Many Thanks, PM.

[Stormyking]

Some very interesting charts indeed today, with latest bringing the risk of snow further South :O, as others say it is only one run but it is still nice to see, especially after last year thats for sure! Hopefully the trend can continue to show as we get closer! either way some promising signs!

[nick sussex]

Given how important the ne USA low is to events in western Europe theres still some time for revisions and even at this stage NCEP highlight still some ongoing uncertainty:

 

AFTER SEVERAL DAYS OF MODEL AND ENSEMBLE FLIPPING... FLOPPING...
AND FLOUNDERING... THE GUIDANCE HAVE STARTED TO CONVERGE TOWARD A
COMMON SOLUTION WITH THE IMPRESSIVE DIGGING MID-UPPER PATTERN OVER
THE EAST COAST AND A COMPLEMENTARY DEEP BUT PROGRESSIVE AND
OPENING TROUGH IN THE WEST. GIVEN THE ONGOING SHUFFLING OF
SOLUTIONS... HAVE OPTED TO USE A MULTI-MODEL/ENSEMBLE BLEND SINCE
THE EVOLUTION REMAINS SENSITIVE TO UPSTREAM DETAILS NOT YET FULLY
RESOLVED. THIS ALSO CONTINUES THE WPC BLEND TREND OVER THE PAST
FEW DAYS WHICH HAS OFFERED MORE STRUCTURED/INCREMENTAL CHANGES.

 

The best outcome if you're looking for cold into the UK is the ne USA low deepens even more, this has the effect of steering this even more to the ne and gives a better chance of developing a stronger ridge ahead near Iceland, its likely that we will see a toppling scenario so the ridge will then topple towards Scandi, the further uncertainty at this stage is where we go after this, troughing in the Atlantic will we see this move into the UK or will some trough disruption occur to see this extend further se with Scandi high possibilities.

 

A good illustration as to how important that ne USA low is to look at tonights JMA and compare the deepening and track and its impact downstream, you'll see it all unravels in terms of cold on the JMA as this fails to deepen the low  sufficiently and takes it east into the Atlantic.
 

Edited October 29, 2014 by nick sussex

[Barry12]

ECM is pretty disappointing

 

[Summer Sun]

Its a shame we don't have the 850's at t144 from UKMO this afternoon out of GFS, GEM & ECM, GFS is by far the coldest

 

GFS

 

 

GEM

 

 

ECM

 

 

And UKMO's pressure chart

 

 

I think its fair to say the start of next week will turn more seasonal with temperatures around average and some snow possible over the Scottish mountains and possibly high ground in England and Wales. For the second half next week we may see some milder air moving back in but this is a bit far out yet so anything could happen.

[marksp]

Just seen this on Meteociel, the GFS in 3d

 

http://www.meteociel.fr/modeles/gfse_3d.php?mode=1

 

Has anyone used it?

nope not seen it until now, great link will be using it lots in future.

[radiohead]

Its a shame we don't have the 850's at t144 from UKMO this afternoon out of GFS, GEM & ECM, GFS is by far the coldest

 

GFS

 

 

GEM

 

 

ECM

 

 

And UKMO's pressure chart

 

 

I think its fair to say the start of next week will turn more seasonal with temperatures around average and some snow possible over the Scottish mountains and possibly high ground in England and Wales. For the second half next week we may see some milder air moving back in but this is a bit far out yet so anything could happen.

 

On those charts, the 850 temperature for the UKMO would be similar to the GFS (old version).

[ANYWEATHER]

Big changes next week, perhaps we will see the first potent spell of cold weather for the season, the detail will change in the next few days , but the trend is there for a major pattern change in our weather....

[heath]

If the cold northerly at t144 comes off, then, from what I can see, the first hints came in the ECM on 22 October.  It has come and gone in the meantime across the models, but if the cold snap comes off it is reasonably impressive that ECM got there so far back.

[knocker]

One interesting suggestion from the GEFS  run, with perhaps some support from NOAA 8-14, is the build of heights to the east and. retrogression and with little amplification to the west. There is quite a marked temp anomaly in eastern Europe.

 

[mushymanrob]

I wouldnt call a potential 24hour or so northerly cold snap a patternchange, the atlantic is predicted on all models to push the cold away rather quickly and without any repeat northerly its more of a blip then pattern change.

[ANYWEATHER]

I wouldnt call a potential 24hour or so northerly cold snap a patternchange, the atlantic is predicted on all models to push the cold away rather quickly and without any repeat northerly its more of a blip then pattern change.

It is indeed a major pattern change given the warm synoptics for weeks now,,,,

[karyo]

I wouldnt call a potential 24hour or so northerly cold snap a patternchange, the atlantic is predicted on all models to push the cold away rather quickly and without any repeat northerly its more of a blip then pattern change.

I totally agree but after a n eternity of mildness and southwesterly winds even a 24 hour northerly is welcome!

[Frosty.]

Tonight's GEFS 12z mean shows strong support for our first of hopefully many cold snaps to hit the uk next week, significantly more so than recently, indeed, it's during the coming weekend when the wheels are set in motion with temperatures falling back to average levels before they tumble further during early next week, impacting highest on the hills and perhaps lower ground of scotland with snow, frost & ice in the forecast for at least a few days..at last it appears coldies will have something to smile about, let's hope the ecm joins the party soon.

Edited October 29, 2014 by Frosty.

[DAVID SNOW]

I wouldnt call a potential 24hour or so northerly cold snap a patternchange, the atlantic is predicted on all models to push the cold away rather quickly and without any repeat northerly its more of a blip then pattern change.

 

 Buts that's the thing, after the northerly, models do show a change from the oh so never ending SSW / S flow to a more average ( temp wise) W flow. Maybe it will turn cooler with a NW flow for a time,we shall see.