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Model Output Discussion - 31/10/2014 and Beyond


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Yes far better run on the GFS 12z compared to the 6z, the two Polar Vortex lobes are split on this run which prevents as much energy coming out of the NE USA. Also much more pressure to the NW of Scandinavia. The blocking is not finished with just yet.

 

gfsnh-0-150.png?12gfsnh-0-156.png?6

 

Day 7 is also a million times better in terms of Northern hemisphere profile...

 

gfsnh-0-168.png?12gfsnh-0-174.png?6

 

The weakening of the polar vortex also continues.

Edited by Barry95
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Yes far better run on the GFS 12z compared to the 6z, the two Polar Vortex lobes are split on this run which prevents as much energy coming out of the NE USA. Also much more pressure to the NW of Scandinavia. The blocking is not finished with just yet.

 

gfsnh-0-150.png?12gfsnh-0-156.png?6

personally i think this is quite a big change and if the pattern keeps on backing west we could get slider galore and eventually get some cold in our part of the world!! Whats causing this though? Is it the warming that is set to begin in the next week or so!!
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Much better NH setup appearing on the GFS 12z. GFS Parallel also following this Is this the model out to +162hr. Textbook example of a split PV.

 

GFS 12z +162                                       GFS Parallel

post-9530-0-32871600-1415896144_thumb.pn              post-9530-0-96209700-1415896178_thumb.pn

 

Certainly becoming a more interesting time for model watching, finally starting to see some progress (albeit slow)

 

Strat forecasts this morning was not something you see everyday either. Here's the chart of the day for people who haven't checked!

 

ECM (Out to 240hr/22nd Nov) 

post-9530-0-19010000-1415896244_thumb.gi

 

Wonder when the models get a grip on this?

 

SM

Edited by SnowMania
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^^^ The ex cold pool from the US is an irresistible force that is going to spill into the Atlantic. Timing issues as to how long it takes to override the block to the NE. The longer it takes the more the longevity of the zonal Atlantic flow. So as Mucka said, a quick flush, and we can send that PV lobe to the NE and allow for heights to build to our south. The 12z op just delays the lower heights so even by D13 we are still under the westerly flow:

 

post-14819-0-45179300-1415896563_thumb.p  D15: post-14819-0-45519200-1415896641_thumb.p

 

 

 

 

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I don't know what the people are moaning about the American cold pool for, it is going to bring colder weather for me at least than what an easterly would bring. The 510 dam line actually makes it out past 50 west, eventually cold will reach here that will provide snow. 

 

The cold pool keeps getting upgraded with each run.

post-22860-0-20795700-1415897113_thumb.p

post-22860-0-87242600-1415897307_thumb.p

Edited by Winter Frost
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Much better NH setup appearing on the GFS 12z. GFS Parallel also following this Is this the model out to +162hr. Textbook example of a split PV.

 

GFS 12z +162                                       GFS Parallel

attachicon.gifgfsnh-0-162.png              attachicon.gifgfsnh-0-162 PARA(1).png

 

Certainly becoming a more interesting time for model watching, finally starting to see some progress (albeit slow)

 

Strat forecasts this morning was not something you see everyday either. Here's the chart of the day for people who haven't checked!

 

ECM (Out to 240hr/22nd Nov) 

attachicon.gifecmwf10f240.gif

 

Wonder when the models get a grip on this?

 

SM

Hi SM could you send me a link to the Strat thread, thanks RK

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I don't know what the people are moaning about the American cold pool for, it is going to bring colder weather for me at least than what an easterly would bring. The 510 dam line actually makes it out past 50 west, eventually cold will reach here that will provide snow. 

 

The cold pool keeps getting upgraded with each run.

 

Noted you are in the North but any cold gets massively modified by the Atlantic so snow to low levels anywhere away from the far North and high ground is very unlikely.

If we get a deep depression with a long NW feed behind then snow showers can fall to low levels further South but it is always transient.

Good for the Scottish Ski resorts perhaps but just cool wet and windy for most.

 

However if low pressure digs South then there is the chance of a ridge building behind should upstream conditions be right and there we can get a nice NW flow turning northerly and have a shot at maintaining a cold pattern.

Edited by Mucka
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I don't know what the people are moaning about the American cold pool for, it is going to bring colder weather for me at least than what an easterly would bring. The 510 dam line actually makes it out past 50 west, eventually cold will reach here that will provide snow. 

 

The cold pool keeps getting upgraded with each run.

 

See that cold front pushing through from the NW. Look what happens as it pushes into the milder air over the British Isles:

 

gfsnh-2-228.png?12

 

 

Rain for everyone except the highest elevations.

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Nice to see the GFS op trying to split the vortex around D8-10: post-14819-0-18765400-1415898032_thumb.g

 

Although it fails and around D13 the warming subsides.

 

GEM shows what happens in the heights to the SW deflect the PV lobe: post-14819-0-71555300-1415898203_thumb.p

 

We still get the ScEuro heights pushed east but we give the Canadian lobe a chance to organise itself. Not sure the implications of that into late November will be good for the UK? I suppose we would get less rain and a milder flow for the south in the short term.

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We still get the ScEuro heights pushed east but we give the Canadian lobe a chance to organise itself. Not sure the implications of that into late November will be good for the UK? I suppose we would get less rain and a milder flow for the south in the short term.

 

Fortunately that's the GEM chart at day 10 and will inevitably be completely different by the time we actually get to that timeframe. No disrespect to the GEM of course but the ECM has far better verification stats and at day 10 is shoeing a rather weak polar vortex. Also I think you better head over to the stratosphere thread if you are worried about the polar vortex into the coming Winter.

 

ECH1-240.GIF?13-12

 

Most of the operational runs today, especially the 12z's have actually weakened the polar vortex at days 7-10. If you look at the runs from yesterday you will see big changes at just day 7, and almost all have a far weaker polar vortex. The trend at the moment is to weaken the polar vortex. I think that trend will also continue with further warming in the stratosphere. Below is the day 7 chart from the GFS 06z, compared with the 12z.

 

gfsnh-0-174.pnggfsnh-0-168.png

 

Much weaker as you can see, and the two pv lobes are split. The trend is the weakening of the pv. You have been posting day 13-16 charts as a sign of the polar vortex strengthening and getting more organized for weeks now, yet here we are with a still very weak polar vortex. I'd have a guess and say that in 10 days time the GEM chart will in reality have a much weaker pv than forecasted.

Edited by Barry95
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Yes elevation is the key if looking for snow in polar maritime air behind a bog standard low.

Prospects of that maybe further on as the Atlantic fires up with some quite cool air coming across from the west.

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=120&mode=1&runpara=1&carte=1

It does like we are going to see some more bands of rain in the coming week. With the block to the east only slowly declining more of the current conditions look likely as lows become slow moving nearby.

Edited by phil nw.
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The Models as expected have backtracked a LONG way today, even the ECM- however the GFS has been hopeless.........

 

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014111312/ECH1-216.GIF?13-0

 

Phantom Easterly coming.

 

S

steve quick question!! Is it down do the warming that is forecasted that is making everything shift West! ! I mean if this carries on we could end up with cold incoming from the north east maybe!!
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what is becoming evident is that when the atlantic does come racing in, it is likely to strike a brick wall whcih will drive WAA north into the arctic. that has positive feedback implications re wave breaking into the lower strat but more importantly, we have no idea where this 'wall' is going to be. i doubt it can get too far to our west, but a building scandi high may well be on the agenda if its anywhere in the vicintiy of the meridian. given the strongly modelled polar profile just the other side of the pole, a building scandi ridge could get interesting going forward.

Edited by bluearmy
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The 240 hour chart is completely different to this morning! ! Atlantic never really gets in and we get high pressure on top of us instead!! Infact the lows in the atlantic might disrupt and slide underneath!

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The GEFS anomalies are very much the same as the 06 run so no real need to run through it all again. Will add the MSL for T168 because if you move the low west and perhaps push the Azores HP a wee tad north will just about sum up the run. Temps still around average or slightly above.

Charts courtesy Wxbell

 

post-12275-0-86295000-1415905195_thumb.p

post-12275-0-54034300-1415905204_thumb.p

post-12275-0-61311900-1415905216_thumb.p

post-12275-0-59390200-1415905251_thumb.p

post-12275-0-74551100-1415905262_thumb.p

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FWIW if you view the NH Jetstream forecasts from the 20th/21st November onwards, something really gives it a kick up the backside, initially over the Pacific region and then as a result from the 26th November (I know deep and darkest FI here) it behaves in a very odd meandering fashion across the globe.

 

I'm no expert on this but could this be the first signs of feedback from the Troposheric/Stratospheric processes mentioned over in the relevant thread. Can someone please enlighten me?

 

Current state of play.

 

post-7183-0-43110700-1415905085_thumb.pn

 

During the period of the weak Easterly/Southeasterly flow this weekend (Sunday 16th November, 3pm)

 

post-7183-0-91078000-1415905127_thumb.pn

 

The first proper re-awakening of the Atlantic perhaps after the calmer although still showery cool start to next week (Thursday 20th November 3am)

 

post-7183-0-96150600-1415905193_thumb.pn

 

What's happening over in the Pacific and Western US seaboard (Sunday 23rd November 3am) DEEP FI by now.

 

post-7183-0-23909800-1415906298_thumb.pn

 

Scary and weird global NH Jetstream profile by t+300, huge pinch of salt (Wednesday 26th November midnight)

 

 

post-7183-0-01441600-1415906323_thumb.pn

 

 

Looking at the above, the period from the 20th November onwards remains a period of great uncertainty. I'm also still not convinced where things will drop for the UK by the end of November but the PV will have most certainly been shifted on by then and if my assumptions are correct, it will be a very different setup by then to the lazy troughing which we are enduring now.

 

Enough of my assumptions, again peeps, what is driving this changes guys n gals? And of note to those whom aren't seasoned model watchers, looking at the NH Jet in isolation on one individual run doesn't necessitate a period dominated by ferocious zonality over on our side of the Atlantic either. Moreover, it might be something much more benign if you look closely. Furthermore, it will lead us into a fascinating period come the end of November and into early December IF this forecasted Jestream pattern type should continue.

Edited by gottolovethisweather
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