General Model Output Discussion:

[Methuselah]

It's charts like today's that bring-out my IMBYist tendency...A fair portion of Scottyland could be in for a bit of a pasting??

As for the Easterly? I guess we'll have to wait and see...

[Lewis]

Good Morning all.

After looking at this mornings GFS, it only amplifies what i said yesterday. In a shorter time frame it just downgrades and pushes forward the Northerly. Come tomorrow i wouldn't be suprised is its more or less vanished..

From wednesday, to thursday, now to friday...

That's why i think looking too far into FI is bonkers.

Nothings nailed on in the short term

Edited January 27, 2010 by Storm Force Lewis

[Nick F]

Morning all, no surprises that one of the models has shaken the faith somewhat for an easterly to develop in the medium range, namely ECM, which has rather backtracked on its dream synoptics of yesterday's 12z in favour of a more progressive Atlantic trough moving across the Atlantic in the upper flow which forces the Azores ridge NE across the UK.

However, as Steve M has outlined in his excellent post above, evolution upstream in the flow across USA, particularly the southern flow across the States, with uncertainty with the track of a low across the mid-west later this weekend which in turn leads to uncertainty to the evolution thereafter downstream. HPC prelim discussions seem to be less keen on 00z ECM after Sunday and opt for a blend of 00z Canadian/00z GEFS mean beyond Sunday evening, so perhaps ECM having a 'wobble':

http://www.hpc.ncep.noaa.gov/preepd/preepd.html

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

310 AM EST WED JAN 27 2010

VALID 12Z SUN JAN 31 2010 - 12Z WED FEB 03 2010

THE COMBINATION OF A NEGATIVE ANOMALY CENTER IN THE MID-LEVELS

EXPECTED TO MOVE NORTHWARD ACROSS EASTERN CANADA AND INCREASINGLY

ZONAL FLOW ACROSS THE PACIFIC ARE EXPECTED TO DE-AMPLIFY/FLATTEN

THE FLOW PATTERN ACROSS THE LOWER 48 THIS PERIOD. THE GUIDANCE

AGREES ON THIS SCENARIO. THE EVOLUTION OF THIS PATTERN TO ONE OF

QUICKER WESTERLIES DECREASES THE CONFIDENCE IN THE MEDIUM RANGE

FORECAST. INDEED...LARGE DAY-TO-DAY DIFFERENCES ARE ALREADY

OCCURRING WITH THE TRACK OF A SYSTEM MOVING THROUGH THE WEST AND

MIDWEST LATE THIS WEEKEND INTO EARLY NEXT WEEK WHERE A SUBSTANTIAL

NORTHWARD TREND HAS BEEN SEEN IN THE GUIDANCE/ENSEMBLE MEMBERS

OVER THE PAST COUPLE DAYS. EARLY IN THE PERIOD WHEN THE GUIDANCE

SHOWS MINIMAL SPREAD...USED A COMPROMISE OF THE 00Z ECMWF/00Z

CANADIAN FOR THE PRESSURES. LATER ON...THE 00Z ECMWF DEPARTS FROM

THE 12Z MULTI-MODEL ENSEMBLE MEMBERS IN MOVING A WEAKER SURFACE

LOW ON A MUCH MORE SOUTHERLY TRAJECTORY THROUGH THE MIDWEST RATHER

THAN THE NORTHERN PLAINS/GREAT LAKES/NORTHEAST. DUE TO THE TIGHT

CLUSTERING SEEN IN THE ENSEMBLE MEMBERS...USED A COMPROMISE OF THE

00Z CANADIAN/00Z GEFS MEAN FROM SUNDAY EVENING ONWARD. THE 00Z

GFS IS A REASONABLE ALTERNATIVE TO THE 00Z GEFS MEAN...THOUGH ITS

SURFACE LOW TRACKING ACROSS THE GREAT LAKES/NORTHEAST IS LIKELY

TOO WEAK.

ROTH

[TEITS]

i dont really know what to make of this fax chart very disturbed stuff coming out of nfl with the alantic ridge drifting south surely this is not good sign for future development of a easterly i hope im wrong though.

Well if that chart became reality then you would find a spell of snow moving into NE Scotland. This would then move south with a spell of snow for other E regions of the UK.

However how close this LP will be when it drifts S is still open for question.

Back to the E,ly and although the ECM is disappointing the GEM/GFS are excellent once again. However the ECM being disappointing isn't a bad thing for me as it stops me ramping!

ECM ensembles are excellent with the OP warmer than the mean around +168

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

[Cloud 10]

Some good posts above which sum the situation up very well this morning.

The ecm seems to have a hangover after its upgrade yesterday but we will see where it sits in the ensembles in a short while.

As Nick F has posted above,NOAA don't seem to happy with the ecm operational this morning and opt for a blend of the gem/gefs mean for the longer term.

GEFS mean@240>

Good to see SM back posting.

Edited January 27, 2010 by Cloud 10

[swilliam]

GEM is not so good today only just making the Easterly

and the NOGAPS shows how it can still all go wrong.

I would say the chances of a good Easterly have reduced from SMs 70% to about 50% based on this mornings output.

[Iceberg]

ECM OPS does not have support for it's 190-240T range from it's ensembles in the 00Z run.

The jet going over the top of the high is at the top of the range...I feel a bit better knowing that. !

[Frosty.]

Good Morning all.

After looking at this mornings GFS, it only amplifies what i said yesterday. In a shorter time frame it just downgrades and pushes forward the Northerly. Come tomorrow i wouldn't be suprised is its more or less vanished..

From wednesday, to thursday, now to friday...

That's why i think looking too far into FI is bonkers.

Nothings nailed on in the short term

Yes the Northerly is now back to friday but with the scandi trough moving westwards it should prolong the arctic spell until mon/tues as the trough fills but the uk remains in a cold pool but then it will either turn milder or remain cold.

[snowmadchrisuk]

I told you last night this is what we would be looking at this morning Don't panic though , Teleconnections are starting to now point to what we want to see so Northern Blocking should start to show more often in the Model output. Amazing how all the models turn at the same time though , I wonder what they have picked up.

[Guest North Sea Snow Convection]

The longer term guidance, as outlined already, still seems reasonable in terms of a cold outlook (after the assured northerly) however we are depending on quite a long timescale for things to keep going right.

It was always going to be the case that some of the modelling would show potential problems with the jet energy equilibrium.

Plenty of time for the ECM to regain its ultra wintry flavoured charts once again, but until they become reliable time period they are nothing more than something entertaining to look at. Much as we all should know anyway.Same applies to GFS and any other computer model as well. And in time, such entertainment tends to lose its inital excitement anyway if/when it doesn't become a reality

It was suggested yesterday that the models may be being over progressive in trying to implement the easterly pattern too quickly and that high pressure close by may happen initially before this happens.

So it could be that the longer term guidance regarding an easterly comes into play after a high pressure interlude post the northerly - but we will see.

In the next 10 -14 days the atmosphere may be better placed to implement the promised northern blocking, as zonal winds slow closer to the troposphere levels and the MMW has a chance to makes its presence felt

Edited January 27, 2010 by North Sea Snow Convection

[BLAST FROM THE PAST]

Excellent post by big Steve MURR. I was looking at Accuweather yesterday or day before and the track of the LP coming off the US is projected SE BUT the forecasters were discussing that it is very likely that nearer the time it will adjust NORTHWARD....as Steve suggests. The amazing charts yesterday surprised me as I thought they picked up on the cold pattern earlier than I thought they would, I anticipate they will ECM particularly, will pick it up again.

The main energy is to go south so any run showing strong northern arm energy is IMO wrong.

BFTP

[Polar Continental]

Morning everyone.

I think the ECM is suffering a massive hangover this morning from its night out with the GFS, it just couldn’t keep the pace.

Still a cold theme as the northerly gets going in the next 24 to 48 hours.

Though after the epic model runs last night, we are brought back down to earth this morning with a different set of scenarios on offer after the northerly.

The GFS and GEM still evolve the easterly, but get there slowly this time with a milder interlude between.

The models this morning are obviously juggling with alternative sets of data, but that’s not for me to explain with my comparatively superficial knowledge, this has been very well dealt with already by Steve M and Iceberg this morning.

Steve threw a few warning shots across the bows last night explaining what could go wrong. Fingers crossed with the 06z .

12z ECM

0z ECM slightly different!!

Edited January 27, 2010 by Polar Continental

[TEITS]

It was suggested yesterday that the models may be being over progressive in trying to implement the easterly pattern too quickly and that high pressure close by may happen initially before this happens.

So it could be that the longer term guidance regarding an easterly comes into play after a high pressure interlude post the northerly - but we will see.

Spot on as usual Tamara.

I would love to see the E,ly ASAP but I actually think what you suggest is more plausible. At the moment the GFS is bang on the date I suggested a few days ago for the E,ly i.e 4th Feb. However im beginning to think this might be delayed by a few days. Love to be wrong though!

The period im particularly interested in is +96/+120. The Met O forecast suggests widespread snow on Sunday for E areas which isn't surprising considering the fax charts. However how close this LP will be to E areas as it moves S is very uncertain.

Seems the 06Z wants to send another disturbance S within the N flow during Saturday night!

http://www.wetterzentrale.de/pics/Rtavn904.png

Edited January 27, 2010 by THE EYE IN THE SKY

[Guest North Sea Snow Convection]

Spot on as usual Tamara.

I would love to see the E,ly ASAP but I actually think what you suggest is more plausible. At the moment the GFS is bang on the date I suggested a few days ago for the E,ly i.e 4th Feb. However im beginning to think this might be delayed by a few days. Love to be wrong though!

The period im particularly interested in is +96/+120. The Met O forecast suggests widespread snow on Sunday for E areas which isn't surprising considering the fax charts. However how close this LP will be to E areas as it moves S is very uncertain.

Seems the 06Z wants to send another disturbance S within the N flow during Saturday night!

http://www.wetterzen...cs/Rtavn904.png

Morning Dave

Yes irrespective of the post northerly period there is enough going on this weekend first of all in terms of features moving southwards. These are never picked up by the models until nearer the time, so it is no surprise to see this already occuring. I think the details are going to keep chopping and changing through the rest of this week in terms of the ppn and who gets snow and the where or when

[PB22]

Not liking the trends of the European models this morning, and now the 06Z GFS is trending away from any easterly in FI:

http://www.wzkarten.de/pics/Rtavn1621.html

http://www.wzkarten.de/pics/Rtavn1622.html

[Cecil Hogmanay Melchett]

Not liking the trends of the European models this morning, and now the 06Z GFS is trending away from any easterly in FI:

http://www.wzkarten.de/pics/Rtavn1621.html

http://www.wzkarten.de/pics/Rtavn1622.html

awful gfs paul i think i heard a pin drop.

[PB22]

We get there in FI, but I don't like the evolution of how it gets there to be honest:

http://www.wzkarten.de/pics/Rtavn2161.html

http://www.wzkarten.de/pics/Rtavn2162.html

Lets see how the ensembles look in a bit before making too many judgements.

[MR EXTREMES]

mmm not a good morning perhapes we might have got excited over nothing lastnight.

the models are dreadfull this morning could it get any worse though it could to be honest.

but saying this its only 1 run.

[Snowly does it]

Slight delay, similar result, one day of mild weather twixt cold spells.

Signals into February remain.

[Lewis]

mmm not a good morning perhapes we might have got excited over nothing lastnight.

the models are dreadfull this morning could it get any worse though it could to be honest.

but saying this its only 1 run.

As TEITS states below, the signs of blocking are still there, these runs are still cracking, it's just the GFS 06z showing a different way of getting there.

Short term is changing all the time, so it's pointless looking past T72 IMHO never mind 165- 384.

A slight wobble on this run, but can you call it a wobble if it agrees with the ECM?

Edited January 27, 2010 by Storm Force Lewis

[TEITS]

the models are dreadfull this morning could it get any worse though it could to be honest.

Rather OTT if you don't mind me saying.

If members are expecting every run to show -15C E,lys then im afraid you're always going to be disappointed.

Lets jog our minds back to early Dec. Virtually all the runs were slightly different to each other as you would expect. However in saying this all the model runs had one thing in common and that was blocking to our N/NE/NW. Now some of the runs had bitter upper temps across the UK whereas other runs were less cold. However as we know the GFS was correct which is why we enjoyed the wonderful cold spell in mid Dec.

So what im basically saying is do not make snap judgements based on one run. Ask yourself is the GFS continuing with the trend of blocking and the answer is yes.

[Tom Montalbano]

Just to add to those comments of Daves' and Tamaras', GFS 06z picking up another feature running SSE/SE overnight Sat into Sun morn. and as it runs into S.Wales/S.Midlands, develops a small centre which slows down its progression south-eastwards. With colder air in situ. as opposed to Friday mornings feature, IMO more of a chance of seeing some snow about early on Sunday morning, for quite a few areas.

http://charts.netweather.tv/gfsimages/gfs.20100127/06/87/h500slp.png

http://charts.netweather.tv/gfsimages/gfs.20100127/06/87/prectypeuktopo.png

http://charts.netweather.tv/gfsimages/gfs.20100127/06/90/h500slp.png

http://charts.netweather.tv/gfsimages/gfs.20100127/06/90/prectypeuktopo.png

Regards,

Tom.

[yamkin]

Slight delay, similar result, one day of mild weather twixt cold spells.

Signals into February remain.

I agree snowmaiden. Easterly is back in FI

Following the above, E/SE flow up to 384h in FI

Edited January 27, 2010 by yamkin

[southbank]

Rather OTT if you don't mind me saying.

If members are expecting every run to show -15C E,lys then im afraid you're always going to be disappointed.

Lets jog our minds back to early Dec. Virtually all the runs were slightly different to each other as you would expect. However in saying this all the model runs had one thing in common and that was blocking to our N/NE/NW. Now some of the runs had bitter upper temps across the UK whereas other runs were less cold. However as we know the GFS was correct which is why we enjoyed the wonderful cold spell in mid Dec.

So what im basically saying is do not make snap judgements based on one run. Ask yourself is the GFS continuing with the trend of blocking and the answer is yes.

Exactly TEITS . The easterly if it transpires was always 5-7 days away so the fact the "trend" is still there and the signals for northern blocking is encouraging . The finer details will always chop and change . if the trend holds then what a finale to the winter months we may have

[TEITS]

to be fair CC thats far from nailed on.Its not just a couple of dodgy ops at all.ecm/ukmo AND gfs have backtracked this morning,actually ukmo didnt look great at 144h to me last night.

it could still happen but you could be setting up for a big fall if thats your position.

You could also argue that the UKMO is out of range, ECM was much milder than the mean at the crucial timeframe and the GFS continues to show an E,ly!

Obviously nothing is nailed on at this stage. What we have to remember is a small synoptic change with regards to the positioning of the block to our NE could make the difference between -5C upper temps and -15C. Infact when I viewing these models at the moment I don't even bother looking at the upper temps!

What staggers me is some never seem to learn. Remember back in Dec when the ECM had a wobble and according to some members the cold spell wouldn't happen? At the moment nobody can say the E,ly is nailed but on the otherhand we can't say the E,ly has gone AWOL. The theme of blocking continues in this mornings output and that for the moment is all we should worry about.