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Model Output Discussion - 31/10/2014 and Beyond


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I think we should reserve judgement on the output once upstream uncertainties resolve themselves.

 

The speed of that cold pool east and its phasing with troughing near the UK is still subject to revision, I still wouldn't discount more energy heading se at that point rather than the current view which sends it over the top.

 

There is no middle ground solution with this type of set up, you either get the high sinking or held further north as some of that trough energy heads underneath.

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Awful in what respect?

It looks standard fayre to me with a cold N/W shot in the latter stages.All set up nicely for early winter.(Grasshopper)

I will post charts when I am home.

? The latter part is exactly like what we had all last winter is it not ? Absolutely horrible.

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Awful in what respect?

It looks standard fayre to me with a cold N/W shot in the latter stages.All set up nicely for early winter.(Grasshopper)

I will post charts when I am home.

 

Set up nicely for winter, with a strong and organized polar vortex?

 

ECH1-216.GIF?12-0ECH1-240.GIF?12-0

 

I don't see this verifying, but they are not nice charts.

Edited by Barry95
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Set up nicely for winter, with a strong and organized polar vortex?

 

ECH1-216.GIF?12-0ECH1-240.GIF?12-0

 

I don't see this verifying, but they are not nice charts.

Sorry I phrased that rather badly.Of course one needs to look at the bigger picture I.e.stratospheric modelling too.I maintain that the latter stages of the ECM are cool/cold and the re-organisation /re-location of the vortex does not end winter purely because of the strength of it Last year

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Sorry I phrased that rather badly.Of course one needs to look at the bigger picture I.e.stratospheric modelling too.I maintain that the latter stages of the ECM are cool/cold and the re-organisation /re-location of the vortex does not end winter purely because of the strength of it Last year

Hi, yes but they seem to be thinking in America that they could see a repeat of last winter. Let's hope not !

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ive found over the course of several years that using the uppers is a pretty good guide to what the surface gets, but hey, we are drifting off topic .

 

The situation in the next couple of days is a good example where there is very little differnce between 850 temps and ground temps - the atmosphere 'cuts' available on meteociel are a useful tool for a quick check.

 

coupegfs_326_102_326_102_48_0_1000_250_u

 

http://www.meteociel.fr/modeles/coupes_gfs.php?mode=7&ech=3

Edited by Nouska
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You got there before I realised the cursor had moved on the timescale - no difference actually. :)

 

As you say. That's a very odd lapse rate without an inversion and given the forecast for Friday an inversion can't be on the cards. :)

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Some interesting comments from NCEP this evening, some bizarre goings on with the amount of warm air forced into the Arctic circle:

 

...UNCERTAINTY ASSESSMENT...

FASCINATING 'SHAKE-UP' OR 'RE-SHUFFLE' IN THE WESTERN HEMISPHERIC

CIRCULATION HIGH-LATITUDE FLOW PATTERN TAKING PLACE---STARTED IN

MOTION BY ENERGY AND MOISTURE ORIGINATING IN THE SOUTHWEST PACIFIC

(TROPICAL SYSTEM 'NURI'). THE ENTIRE AIRMASS HAS PUSHED NORTH OF

THE ARCTIC CIRCLE. BARROW ALASKA WAS WARMER EARLIER THIS MORNING

(UTC TIME) THAN AMARILLO TEXAS.  

 

You'll also see comments re teleconnections below:

 

USING THE WPC TELECONNECTION TOOLS IS INTERESTING---THE POSITIVE

ANOMALY (UPPER-LEVEL HIGH) CENTERED OVER NORTHEAST ALASKA SUGGESTS

MAINTAINING A STEADY DRAW OF CANADIAN ARCTIC AIR INTO

MONTANA...WYOMING AND THE DAKOTAS---SIMILAR TO THE CURRENT

CONDITIONS---THROUGH THE DAY +8/+11 TIME FRAME. CONTRAST THIS TO

THE NEGATIVE ANOMALY---TELECONNECTING THE FORECAST CALLING FOR AN

UPPER-LEVEL LOW OVER SOUTHEAST HUDSON BAY. THE TELECONNECTION

SHIFTS THE ENTIRE COLD 'FOCUS' AT DAY +8/+11 TO THE

MIDWEST...GREAT LAKES AND SOUTHERN PLAINS---ESSENTIALLY THE ENTIRE

LANDMASS AREA EAST OF THE CONTINENTAL DIVIDE. SO THE QUESTION

IS---WHICH ANOMALY TO BASE THE FORECAST ON? OR EVEN BETTER---WHICH

TELECONNECTION IS MORE SIGNIFICANT AND 'UNUSUAL'?

THE UPPER-LEVEL RIDGE IS THERE NOW...AND THE UPPER-LEVEL LOW?

ANOTHER 36 HOURS AWAY AND HARD TO TELL TODAY WITH THE AIR

TEMPERATURES AHEAD OF THE FRONT---ALONG THE EAST COAST

TODAY---UNSEASONABLY MILD.

 

If the models hold the cold back further west in the USA this then would reflect less eastwards movement of the cold pool. Which would impact the eastern USA and downstream in western Europe.

 

 

This animation of the 500mb Arctic circulation, from Global weather logistics, gives a fantastic insight into the forecast disturbance. Model is the GFS.

 

http://globalweatherlogistics.com/seaiceforecasting/gfs.500mb.temps.arctic.html

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This isnt too bad is it? Pretty cold uppers towards the end of the run on ECM tonight. I think I asked this last year and -4 should be enough for some wintryness on high ground at least, as this is going on end of November time?.....

 

ECM0-192.GIF?12-0ECM0-216.GIF?12-0ECM0-240.GIF

 

Unlikely to happen of course anyway :)

We had a lot of that last year, very cold air from the far NW flying across the Atlantic towards us. Great for the Scottish ski industry but for almost everyone else the cold air only fuels the Atlantic and batters us with wind and rain.

 

Looks like a seriously turbocharged jet setting up on the ECM. If that gets going one feels it's going to take some stopping, especially with those intense low heights to our NW which may get resupplied by the other main area of the PV over Siberia which looks a persistent feature.

 

Still, early days and all can change by early-mid December. Wouldn't be getting worried yet unless you're impatient for early cold/snow.

 

ECH1-240_tlb6.GIF

Edited by Bobby
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ECM ens

EDH1-168.GIF?12-0

EDH1-240.GIF?12-0

To be honest the 12z op is probably on the extreme end (opposite to the 00z run albeit) of the set. Weak heights over the pole should probably prevent a full onslaught if this were to pan out. We still probably see an unsettled spell into week 2 with winds from the south west, but maybe not to the extent of the weather we saw last winter.

 

That said the recent output does suggest that Arctic blocking can result in pretty awful conditions for the UK, a NW Canadian/Siberian cross polar ridge is about as bad as you can get as the ridge directs all of the cold Siberian air towards Canada which in turn drives an increasingly mobile pattern.

How long will this last? Probably not too long (a week or so). But a lot can change.

Edited by Captain shortwave
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I think what the models are going through is a really difficult time of forcasting. I remember the term "Shannon empathy" a couple of years ago where the models swing one way to the other and nothing past t144 could not be trusted as some things that are so small early on could lead to lager consequences later on. So I would say we are in a period of Shannon empathy

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Having noted Nicks earlier post one has to view the anomalies tonight with a certain caution. Having said that NOAA and GEFS are singing from the same hymn sheet.

 

Alaska high and weakish heights Scandinavia and vortex over Russia. Troughs Pacific and NE Canada aligned into the Atlantic.with the jet zipping around the latter. Thus surface analysis of low pressure SE Greenland and the retention of the unsettled westerly airstream for the UK Not much change in the extended period although the Alaskan HP weakens and the Scandinavian block being ineffectual.

post-12275-0-49606500-1415825549_thumb.g

post-12275-0-66709900-1415825558_thumb.g

post-12275-0-90174800-1415825567_thumb.p

post-12275-0-14849300-1415825581_thumb.p

post-12275-0-32886000-1415825590_thumb.p

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I'm glad this Shannon is feeling for us at this difficult time. :D It's shannon entropy I believe :)

 

Though I agree that's what could be causing this, if I remember right, it was characterised by a neutral AO despite a weakened vortex, which is what is being forecast for the next week.

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Sticking to the reliable timeframe i.e. out to Monday a fairly static picture with the slow moving trough anchoring itself down over the country providing bands of rain or showers and fairly mild conditions - a dank outlook if ever, where is the sunshine is what many will be saying over the coming days.

 

By Sunday we will see a more SE drift, making for slightly cooler conditions but still very grey for many.

 

Thereafter all eyes on events over North America - its a very volatile extreme set up over there coming up this is going to make the models struggle, don't be too certain on a sudden change in gear in the atlantic even with the projected cold air due to spill off the eastern seaboard. The timing and positioning of trough action off the eastern seaboard and how this interacts with the jet is key. Also the sudden change over N America is certainly not a symptom of longer term northern hemispheric developments which makes me speculate loss of projected strong heights over the Pole could very easily be a very temporary affair..

 

 

 

 

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I think what the models are going through is a really difficult time of forcasting. I remember the term "Shannon empathy" a couple of years ago where the models swing one way to the other and nothing past t144 could not be trusted as some things that are so small early on could lead to lager consequences later on. So I would say we are in a period of Shannon empathy

I think you're referring to entropy rather than empathy?

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By Sunday we will see a more SE drift, making for slightly cooler conditions but still very grey for many.

Fog also looking prevalent in E Anglia/SE for Sat-Sun. But at least the cool-off is only modest, so not too chilly (frost unlikely where skies clear).
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Its business as usual, the phantom easterlies are replaced by the roaring westerlies. There is plenty of time for winter to be honest and im glad that any so called wintry spelll .on offer as no wintry spells so early on...

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If theres to be any model drama over the next few runs its likely to happen between T144hrs and T168hrs. Its this part of the output that could cause more variability, so far the modelling isn't interested in taking much energy se'wards so this goes ne and helps to pull those low heights with it.

 

The best hope for more energy heading se is with the UKMO T144hrs,  remembering here that timing is an important part of how synoptics interact, if the upstream pattern de-amplifies later than expected this delays the push east of those low heights out of the ne USA.

 

We shouldn't assume that the models have nailed the timing or the amplitude of that wave that initially helps to dig that trough energy south into the Atlantic, the suggested outlook by the means or most of the operationals whilst looking like a slam dunk is actually a lot more on a knife edge than either the ensembles or operationals suggest.

 

The current favourite is the high sinking, however even favourites can unseat the rider at the trough disruption hurdle!

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Its business as usual, the phantom easterlies are replaced by the roaring westerlies. There is plenty of time for winter to be honest and im glad that any so called wintry spelll .on offer as no wintry spells so early on...

 

I think you are looking at the wrong output.

 

All models at 96-144 have an easterly flow of some kind. whether that be SE or E-

 

...

S

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