Model Output Discussion - cold spell to end Autumn

[carinthian]

You could not make up these charts if you tried. Unbelievable . GFS ends with what looks like the longest Easterly in history ? The ECM ends with a rain and wind fest with a deep low spawn by a West Greenland short wave from hell. Probably none will work out like this, but we must never say no ! Pressure, blocks up and down like a yo yo. Love it.

 C

[knocker]

Not surprisingly the ecm also has a trough lying along the north east coast tomorrow with a band of precipitation so quite possible a fair dose of snow showers/longer periods? but it might well be a little knife edgy. Best consult the more detailed models,

Further afield it starts to diverge from the gfs at the beginning of the week as it has the frontal wave  more advanced and further north so that at T144 it is over the coast of central Norway with a second wave and front moving east over Scotland through Monday night into Tuesday. This front is the boundary between the warmer air to the south and the colder air to the north/  It quickly moves east into Denmark leaving much of the UK in cold north westerly airstream by T168 with wintry showers in the north and west.

But this is very transitory as the high pressure to the west comes under severe pressure from.troughs tracking from the south east seaboard and the north west and after some brief ridging into the UK at T192 it is swamped by a significant Atlantic low.as gales and heavy rain, not forgetting much warmer air, descend on the UK from the west.

No need for me to say it as the major uncertainties regarding next week are blatantly obvious and suerficially it all seems to be down to the handling the upstream energy flows out of North America which in turn could be related to this

 

[Gavin Hannah]

There's only one way to describe what the GFS produced on the 00z....  Utter Filth.  FI evolutions are obv chalk & cheese and so I wouldn't look much past this weekend.  But what's nice to see is consistency from the GFS Re. a Northerly reload next week.  By this weekend, we should have a decent amount of high ground snow. If we get that quick reload next week, with the increased snow amounts progged, it should be a rather decent ski season up there.  Fingers crossed for the GFS to keep any blowtorches well away from us!

Edited November 29, 2017 by Gavin Hannah

[bluearmy]

Ecm creates the largest trigger low in history !  Much better upstream over the states than past couple runs around days 7/8.. yesterday's clusters showed about a 25% chance of the mid Atlantic ridge making it through week 2. 

Remaining very uncertain with the gefs resetting the markedly neg AO out to 16 days again. 

[blizzard81]

51 minutes ago, ShortWaveHell said:

The WAA approaching Greenland at 216 should have happened at 168-192 until the ECM managed to spawn a miniature hurricane 

Indeed. I have see rapid cyclogenesis but that is surely just taking the mickey. I have seen the ecm have some very unrealistic progressions but this beats them all. It always seems to be the progression from 168 to 192 hours as well.  

[Seasonality]

15 minutes ago, bluearmy said:

Ecm creates the largest trigger low in history !  Much better upstream over the states than past couple runs around days 7/8.. yesterday's clusters showed about a 25% chance of the mid Atlantic ridge making it through week 2. 

Remaining very uncertain with the gefs resetting the markedly neg AO out to 16 days again. 

You mean this happy fellow? Have included GFS as well to compare and contrast. I do like that Euro tough on GFS!

 

Edited November 29, 2017 by Seasonality

[Seasonality]

Hemispherical view shows lovely little blob of heights directly over the pole.

[bobbydog]

may i suggest an easterly? 

and is that a Murr sausage?

 

[Seasonality]

2 minutes ago, bobbydog said:

may i suggest an easterly? 

and is that a Murr sausage?

 

I can't remember the exact definition of Murr sausage, if indeed there is an 'official' one. I recall something to do with a sausage shaped blob of high pressure stretching from Iceland. @Steve Murr if you read this can you help out?

[NO LONGER POSTING]

Interesting fax charts for Eastern counties and South East England tomorrow into Friday... Think there will be a fair few surprises from now till Saturday morning for quite a few people, a lot of disturbances running down the north Sea.. 

For instances this trough showing comes right across the south east.. 

[bobbydog]

Just now, Seasonality said:

I can't remember the exact definition of Murr sausage, if indeed there is an 'official' one. I recall something to do with a sausage shaped blob of high pressure stretching from Iceland. @Steve Murr if you read this can you help out?

hi mate, i know roughly what it is, i was more suggesting one could be forming in that chart 

[Severe Siberian icy blast]

55 minutes ago, carinthian said:

You could not make up these charts if you tried. Unbelievable . GFS ends with what looks like the longest Easterly in history ? The ECM ends with a rain and wind fest with a deep low spawn by a West Greenland short wave from hell. Probably none will work out like this, but we must never say no ! Pressure, blocks up and down like a yo yo. Love it.

 C

I'm very douptfull a cut off low like that with no help from the vortex will have the legs in it to deepen as much as it does across the Atlantic, granted it may well react with the temperature gradient but not to the extent it has on some of the models. 

It's gonna take until the Friday at the earliest for the models to get a grip on next week but id favour cold returning 65%/35% imo.

[Seasonality]

1 minute ago, bobbydog said:

hi mate, i know roughly what it is, i was more suggesting one could be forming in that chart 

I've no doubt you do  I see the term bandied about a bit and know its a slang term. But I just can't remember how to define it. If you can help out I'll be grateful.

[Day 10]

Still no point in looking past 144:

FI earlier really, but to keep things simple, here is the GFS 144 and then 192:

   to this at 192  

And now ECM 144 and then 192:

   to this at 192 

Much to be resolved, but still looking ok to me early doors.

Edited November 29, 2017 by Day 10

[joggs]

5 minutes ago, Seasonality said:

I've no doubt you do  I see the term bandied about a bit and know its a slang term. But I just can't remember how to define it. If you can help out I'll be grateful.

I think it's a narrow/squashed area of high pressure stretching anywhere nw,n,ne  of us deflecting the jet South and hopefully giving  a great beasterly.

If someone could post the chart up for 1978/79 winter I think, was a great example.

Edited November 29, 2017 by joggs

[Chesil View]

Just now, bluearmy said:

Ecm creates the largest trigger low in history !  Much better upstream over the states than past couple runs around days 7/8.. yesterday's clusters showed about a 25% chance of the mid Atlantic ridge making it through week 2. 

Remaining very uncertain with the gefs resetting the markedly neg AO out to 16 days again. 

As long as it keeps heading south/southeast blue  I'll be happy.

[MR EXTREMES]

9 hours ago, Steve Murr said:

I think the GFS has performed quite well in the run up to the current Northerly spell & its settling down again after the nervy moments this morning

A wedge of high pressure does seem to get through however its the atlantic trough thats causing all the trouble-

The GFS eventually brings it east to reinvigorate the Northerly where as the ECM ejects it out North-

History tells us East... through the highs midpoint

GFS 144 shows what I think is going to be a fair locale before it starts tracking east -

 

More nervous this morning glad the gem is not the top model.

GFS continues the incredible northerly no marginal snow event country wide extremely cold.

Ukmo don't look that great at 144 we see lows drop south to far to our east.

But saving grace is Europe is definitely going into the freezer.

But we are on knife edge situation as things seem to be east of the uk.

Other than the GFS,

I don't think I'm brave enough to say the GFS is correct.

Although the other top models would have us a little more settled except for the far north.

Although still plenty of interest.

But I'm firmly on the fence.

[nick sussex]

And so the longwinded saga has been given a second series today!

They obviously saw the NW viewing figures and decided there was demand so today we have a complete mess with dismal continuity from the ECM!

The UKMO and ECM are closer upstream with the placement of key features and the former has a similar shortwave to the ECM over ne Canada, but you end up with two different scenarios at T168hrs. We don't have the full UKMO view but from what we can see shortwave energy is absorbed into the main low and doesn't eject as a separate shortwave low.

The trouble area and which is causing big problems is here:

ECM

 

UKMO

 

NOAA had this to say about todays outputs:

IF ANYTHING, NEW 00Z GUIDANCE THUS FAR ADDS EVEN MORE UNCERTAINTY.
THERE NOW SEEMS TO BE A BIT OF A FASTER ADJUSTMENT WITH THE
TROUGH AS IT ARRIVES.  THEN THE GFS/UKMET CLOSE OFF A COMPACT
UPPER LOW ALONG THE CENTRAL CA COAST BY LATE MON WHILE THE CMC
SHOWS A PROGRESSIVE UPPER LOW WHOSE ENERGY REACHES UP TO THE MS
VALLEY BY DAY 7 WED.
 

Positively this points to a window of opportunity for the UK downstream:

THE MOST AGREEABLE ASPECT OF THE MEDIUM RANGE FORECAST IS THE
TRANSITION OF THE MEAN PATTERN FROM ONE OF LOW AMPLITUDE AND
PROGRESSION TOWARD A HIGH AMPLITUDE/PERSISTENT REGIME.  THE END
RESULT BY DAY 7 WED SHOULD BE A STRONG RIDGE ORIENTED NORTH-SOUTH
NEAR THE WEST COAST WITH A DOWNSTREAM TROUGH EXTENDING SOUTHWEST
FROM THE UPPER MS VALLEY/GREAT LAKES.

The problem at the moment is exactly how this translates downstream which as we've seen is far from being resolved.

I personally don't like the ECM because its ridiculously deep trigger low tracks unfavourably and will take time to fill, you want a low se into the continent and not dropping south, even with that it just throws another curveball into proceedings.

With cold synoptics in the UK the cleanest and quickest solution is best because more time more chance of another variable popping up.

 

 

[blizzard81]

Debilt ecm ext ens trending much colder than last night's run

[johnholmes]

No real help from the anomaly charts, see below, no real agreement with one another. The NOAA version has shifted from its meridional pattern to a more westerly type, still with very slight ridging towards Greenland. So I suspect the idea of any deep cold, other than a 24-48 hour type, is not likely in the next 2 weeks, once the less cold type sets in by the end of this week.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

[karlos1983]

We've got to be happy with that UKMO D7 chart surely..

[blizzard81]

5 minutes ago, karlos1983 said:

We've got to be happy with that UKMO D7 chart surely..

Absolute cracker

[BlueHedgehog074]

5 minutes ago, karlos1983 said:

We've got to be happy with that UKMO D7 chart surely..

Does look like a possible Northerly trying to poke through on that chart for the U.K, as that Low to our North slithers down to our East!

[carinthian]

9 minutes ago, karlos1983 said:

We've got to be happy with that UKMO D7 chart surely..

Yes, that's a encouraging chart at 168t. High retrogression and Atlantic trough extending towards Azores. Possible opening up for another attempt of Arctic air mass into the British Isles.

C

[karlos1983]

5 minutes ago, blizzard81 said:

Absolute cracker

 

3 minutes ago, DiagonalRedLine said:

Does look like a possible Northerly trying to poke through on that chart for the U.K, as that Low to our North slithers down to our East!

Nice angle on the Atlantic Low, looks very undercutty.....