Model Output Discussion - 31/10/2014 and Beyond

[Barry12]

We still end up with an Easterly on the GFS P

 

[NorthernRab]

Its in post #1103 the spoiler...

 

S

My bad!

[Polar Maritime]

The Atlantic starting firing up into the run, Although very weak at this point. Just look how South the Jet is and very Meridional to.. Some very wet weather to come as systems bump into the High just to our East, Stalling them over the UK. Flooding may also become an issue.

 

 

Edited November 10, 2014 by Polar Maritime

[Nick F]

Not ideal the 18z op or parallel for anything cold soon, though the Atlantic at least remains blocked east of the Meridian.

 

On the plus side, the parallel run shows two distinct Rossby waves (wavenumber 1 NW Canada/Alaska and 2 over Greenland) at t+264 which may continue to propagate into the stratosphere and put pressure on the troposheric polar vortex.

 

 

Deep cold air flooding SW into NE Europe too by t+300

Edited November 10, 2014 by Nick F

[Snowmadsam]

Well hello to you, folks!!

 

NEWS FLASH TIME!!!! OPI winter forecast has been released, suggesting a -AO and -NAO...

 

You can read the rest here :- http://app.til.it/opi/

 

But for a sneak peak :- 

 

[Snowy L]

Good end to the parallel, some brilliant WAA over Greenland

 

http://www.wetterzentrale.de/pics/Rpgfs2162.gif

[knocker]

Good end to the parallel, some brilliant WAA over Greenland

 

http://www.wetterzentrale.de/pics/Rpgfs2162.gif

Quite brilliant over the UK as well I would have thought

[Duane S.]

Shamelessly cherry picked from the 00z ens, this rather tasty offering...

 

Complete outlier at the tail end but trawling through the GEFS output in recent days more members are bringing cold scenarios closer to our shores. Woldn't be surprised to see this reflected in the GEFS 850hpa forecast with the mean value dropping below 0 in about a week, i.e. for the end of the month

Edited November 11, 2014 by s4lancia

[knocker]

Looking at this mornings GEFs T264 anomaly (agrees with yesterdays NOAA 8-14) Three significant features. HP Siberia and Scandinavia ridging across the l pole and deepish trough in the Pacific and NE Canada troughing east across the Atlantic. This brings instabilty and low pressure across the Atlantic but also dragging warm air into Greenland and across the UK. Thus the latter has above average temps. There would appear to be no significant variation on this scenario in the extended period apart from a slackening of the HP. It should perhaps be noted regarding the warm temps along the western seaboard the the SSTs this year are abnormally warm. A glance at the T anomaly with T1534.

Charts courtesy WxBell

Edited November 11, 2014 by knocker

[Captain Shortwave]

Probably at the moment the best result we can hope for.

A possible high close to the UK bring chilly and frosty conditions.

The GFS and GEM favour the Euro high backing west with a developing Atlantic trough. None of the models really want to separate the two lobes of the tropospheric vortex, hence allowing cold unstable air to feed into the Canadian lobe and allows low pressure to form and move north east across Greenland (The so-called spoiler shortwaves).

Perhaps there is a chance of anticyclonic conditions developing beyond mid-month, but no real sign of cold weather coming our way other than an inversion set up.

[Nick L]

The end of the ECM is quite remarkable. On the face of it you would expect it to be bitterly cold but it's just mild! Even get a Channel low thrown in at +216, if only we had some cold air to tap into...

[Polar Maritime]

The GFSP this morning continues to show fronts stalling over the UK, Hitting the block to our East, Before the Atlantic fires up around the 21st from the W/N/W.

 

[terrier]

Certainly looks like the cold from the States is once again firing up depressions heading straight for the uk on this mornings gfsp. With the low pressure hitting the block to the east. Think flooding could well be a issue in next few weeks.

[IDO]

It was always the case of how long the trough remains over the US and how it's departure reboots the Canadian PV lobe. A less amplified flow was likely to favour a more westerly flow and that is the GFS Parallel & Control take on things:

 

 

 

The old GFS op is more in line with GEM and ECM, with a seemingly temporary flow of energy between the Canadian and Siberian Vortices:

 

  

 

So how they handle the PV from around D7 could determine whether it is a wet and windy last third of November or a drier one for the UK. It appears to resolve around the D5-6 shortwave spoiler that splits its energy, part going towards the sister vortex and the other heading SE towards the UK:

 

 

ECM, GEM and the GFS op build a ridge in after this LP system tracks SE whilst the GFS P/C does not and that LP system acts as a conduit for the energy spilling off the Canadian lobe. Pressure will always try to equalise and that is one of the reasons these spoilers pop up. Given half a chance it will head for the other vortex and that Greenland short wave spoiler did just that.

 

So a case of waiting to see how this resolves next week. As for another HL blocking pattern before the end of November this looks very unlikely. The PV continues in FI to show no clustering, so although more organised than coming up, it remains out of phase with the expected profile: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=384.

 

Different opinions as to when the strat will feed to the trop; from early to mid December, and initially a displacement looks favourite. So a case of waiting it out, and bearing in mind Winter is still weeks away, this is no bad thing.

 

 

[Polar Maritime]

Fantastic cross Model analysis there if i may say so I'm Drea.. Yes as you quite rightly put it, it does look like the Atlantic will win out this time round. But with the PV still remaining displaced, The question is for how long. 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY NOVEMBER 11TH 2014.

NEXT UPDATE WEDNESDAY NOVEMBER 12TH 08:00

THE CURRENT GENERAL SITUATION Slow moving troughs of Low pressure over Western Britain will edge slowly East across all areas tonight and tomorrow with a showery SW flow following.

MODELS-2 WEEK HEADLINE  Unsettled with rain at times across the British Isles especially over the South and West. Drier and slightly colder weather over the North and East for a time from this weekend.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows little sign of any significant shift in the flow from it's 50-55 deg North location with just varying strengths and orientation this side of the Atlantic the only changes through the period.

GFS OPERATIONAL Today's GFS operational run shows the UK under bombardment from Low pressure areas crossing the Atlantic and becoming slow moving close to the West and SW of the UK with repeated spells of rain and showers affecting the UK especially the South and West with mild Southerly winds for all through Week 1. Through week 2 the pattern is shown to relax as pressure builds, first from the North and then over the UK with fine weather developing for all with frost and fog night and morning, slow to clear in the day and as a result it could feel very chilly.

THE GFS PARALLEL RUN The GFS Parallel run carries the same sequence of events through Week 1 with the Northern High pressure to the NE collapsing later with a more direct hit of Atlantic wind, rain and gales for all as a result with Low pressure allowed to cross the UK directly at times rather than being held up just to our West in potential storminess later in week 2.

THE GFS ENSEMBLES  The GFS Ensembles are similar in stance to the Parallel run in as much that Northern blocking collapses by early next week with rain and gales sweeping the UK on a strong and occasionally stormy SW wind in association with deep Low pressure areas crossing East close to NW Scotland. Mild weather is shown to persist for all.

UKMO UKMO today shows Low pressure close to SW Britain filling slowly with time but sufficiently strong enough to continue rain and showers across the UK in a cyclonic flow with pressure quite High to the North and NE keeping the wettest weather away from these parts.

THE FAX CHARTS  The Fax Charts maintain the theme of Low pressure just to the West of the UK throwing troughs North and East across the UK. The Eastward shift is much slower with repeated waves running quickly North across the UK with copious rainfall events in Central and Western areas while there will be more showery interludes and  drier weather more generally towards the NE.

GEM  GEM shows Low pressure in total control of the UK weather over the next week as deep Low pressure drifts slowly ESE towards Southern England by a weeks time filling steadily. Rain and showers for all as a result will slowly become confined to Southern parts before a build of pressure develops High pressure over the UK by Day 10 with fine and dry weather for all then with some sunshine but fog and frost at night too.

NAVGEM NAVGEM keeps Low pressure domination across the South of the UK with a deep centre over the Atlantic drifting down over Southern England by early next week filling steadily. As with GEM rain for all at first will become more restricted towards the SW for a time before a renewed Atlantic attack returns NE across the UK later as High pressure to the North and NE collapses.

ECM  ECM this morning shows a very similar pattern of deep Low pressure making it's way down into Southern England by next weekend with rain at times for all becoming more restricted to the far South later as the Low fills in situ and High pressure to the North and NE becomes more influential. It doesn't look like holding though as the Atlantic pattern at Day 10 seems poised to make a renewed attack soon after term of the run.

THE ECM ENSEMBLES   The Ensembles point to a SW flow of some sort the most likely outcome covering the UK in 10 Days time in association with Low pressure over the NW Atlantic and higher pressure over Europe. No doubt that troughs of Low pressure will lie somewhere close to the UK delivering rain at times in continuing mild conditions.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend today shows something of a rise in pressure from the North and NE by next week though particularly cold weather as a result of this seems unlikely.

MY THOUGHTS  There is something of an agreeance in the sequence of events through much of the output this morning. This week and next weekend is agreed by all output as the well worn Low pressure belt from Western Britain and the Atlantic persists with slow moving troughs crossing slowly East and more quickly North over the UK continuing with heavy rain at times especially in the West and South in mild conditions generally. With Low pressure then shown to fill steadily as it reaches Southern Britain early next week the North and East looks like becoming dry and perhaps bright as higher pressure to the North begins to ridge down. With no cold air to tap into we have to rely on our own home made chill from frost and fog at night to bring temperatures down to average levels for many next week more likely in the North and East. The main differences between output this morning then hinges on how successful this build of pressure from the North is in first displacing any Low pressure close to Southern Britain at that time and secondly how successfully it holds any push of the Atlantic back over Britain as the block to the North becomes displaced. It does look generally accepted between the output today that the belt of High pressure to the North will not give the UK any particularly cold weather this time as it is favoured to collapse away SE next week as deep Atlantic Low's to our NW take over and possibly deliver SW gales and heavy rain at times for all in average temperatures then. The lone cold weather flag is flown by the GFS operational in it's last few frames offering the only chance of cold from the NE possible. My own thoughts are that the Atlantic will win out after a short hiatus for some Northern and Eastern parts over the weekend and early next week with rain most likely in the South and West extending back to all areas later next week with temperatures still holding at respectable levels well out towards the end of November.

[Great Plum]

You know that winter is coming when there's some outlandish outliers on the GFS ensembles

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Nice cold frosty high anyone?

http://www.wetterzentrale.de/pics/Rtavn3841.gif

If only

[karlos1983]

You know that winter is coming when there's some outlandish outliers on the GFS ensembles

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Nice cold frosty high anyone?

http://www.wetterzentrale.de/pics/Rtavn3841.gif

If only

 

Nice precip spike as well 

[Mair Snaw]

You know that winter is coming when there's some outlandish outliers on the GFS ensembles

http://www.wetterzentrale.de/pics/MT8_London_ens.png

Nice cold frosty high anyone?

http://www.wetterzentrale.de/pics/Rtavn3841.gif

If only

Looks like a nice bit of WAA heading toward the west of Greenland?? not the best at reading the charts so if im wrong could somebody explain...thanks.

[Great Plum]

Bigsnow - I think that if the charts continued that would probably happen...

See the upper air temps - -5 air across much of the country under a high pressure - sunny and frosty potentially! And look to the east!

http://www.wetterzentrale.de/pics/Rtavn3842.gif

Yes, I'm aware that this is conjecture and is extremely unlikely to happen but...

[Nick F]

My latest thoughts on the weather patterns affecting us over the next 14 days and even beyond are now in a blog here:

 

http://www.netweather.tv/index.cgi?action=news;storyid=6284;sess=

 

Certainly a shift from models over last few runs, with the break down of the ridge over Alaska/NW Canada while the reloading trough over E Canada, central and eastern US strengthens and eventually shifts east over Greenland/NW Atlantic - which could eventually re-ignite an Atlantic depression conveyor across the UK. But still uncertainty for this outcome, given ECM's and GFS's operational runs which suggest blocking over Europe holding back such an advance.

 

Longer term still potentially looking very different to last winter going by the Eurasian snow cover signal, -ve QBO and now the OPI winter forecast all hinting at a -ve AO and so potential for cold and wintry spells this winter.

Edited November 11, 2014 by Nick F

[Man With Beard]

So how is the ECM doing with this set-up? Here's a countdown on how it has got to the current T144, starting from T240.

 

First up, the ECM ensemble mean. Notice how the Arctic High slides away as each day passes, and the PV gradually moves in to take its place. Heights over Greenland are reasonably consistent, a slight build as each day passes but today's T144 is quite similar to T240. The cut-off low also develops with time.

 

 

Overall, not bad, fairly consistent except too bullish with the Arctic High - the cut-off low appeared later but you wouldn't expect a T240 mean chart to pick that up.

 

On to the ECM op runs and oh dear, what a mess, particularly after T168. 

Some people say "the ECM isn't as good as it used to be" - is that because we never used to see beyond T168? My feeling for a long time has been that the ECM T240 chart is often poor, and even T192 / T216 can't be trusted that much. Looking at the charts above, to be frank, you could bin all the op runs except the T144/T168 ones.

 

On the other hand, the ensemble mean has provided quite a good guide even from T240 because of its consistency, and even the changes on the chart have some progression to them. The mean, of course, has had its failures too (I remember January 2014 when an undercut changed to an overcut at T96). But on the evidence of this particular debacle (so far!), the mean is the one to track at long distances, not the op.

 

Will be interesting to see if the op veers back towards the mean tonight. 

[summer blizzard]

GFS, GEM and Euro all singing from the same sheet by day 10 with a build of pressure closer to the UK. 

 

Not the freezing beasterly we wanted but could be sunny and chilly..

 

[Gael_Force]

Talk about chalk and cheese!

 

 

This, from the same starting conditions, can develop to such disparity at only 336 hours - those fretting about winter LRFs  take note: if the regular NWP has such difficulties resolving the atmosphere, how the blazes can we even contemplate monthly and beyond as being in any way accurate.

[knocker]

The T1534 doesn't seem to be on the same sheet sb

Courtesy WxBell

Edited November 11, 2014 by knocker