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Model Output Discussion - The Start Of Winter


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I am normally a lurker but looking at this chart from GFS(P) what is going on in the north of Spain - armageddon, black hole?

I used to live around there, and given the right conditions they can indeed have horrendous rain totals in winter - a mixture of Atlantic lows and a warmer climate. The snow will be for the mountains, there is a large area of land at or above 1000m in that corner

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A few of you have asked today about rationale for the (tail-end of) UKMO latest 30-day outlook. There is, of course, a dedicated thread elsewhere for this but I'll just confirm that GloSea5 output rem

Thanks for this Barry   You are however wrong on both counts you suggest :   1) I have explained in extended detail, as much as I am able, the progress of the patterns thus far from autumn (see firs

Hopefully a timely interjection, but UKMO caution (again) that medium range NWP may not be adequately reflecting ultimate broadscale outcome. First tentative signs emerging, they suggest, of *possible

Posted Images

Looking at the NCEP discussion they're happy to go for the more amplified pattern and you'll note they talk about a possible negatively tilted trough near the Great Lakes.

 

ACTIVE SPLIT-FLOW PATTERN OVER THE CONUS WILL TRANSITION TO A MORE
AMPLIFIED RIDGE/TROUGH WITH A POSSIBLE NEGATIVELY TILT TROUGH
SETTING UP OVER THE GREAT LAKES BY CHRISTMAS EVE. A BREAK/BUCKLING
IN THE STRONG WESTERN/CENTRAL PACIFIC JET BY SUNDAY WILL BE THE
IMPETUS FOR AMPLIFYING THE PATTERN DOWNSTREAM OVER THE CONUS. THE
MODELS/ENSEMBLES HAVE WAVERED IN DETAILS BUT HAVE MOSTLY KEPT ON
TOP OF THE PATTERN SHIFTS... WITH SOME OVER/UNDER AMPLIFICATION
EVIDENT AT BOTH LARGER AND SMALLER SCALES. THAT BEING SAID... A
COMPROMISE/BLENDED APPROACH SEEMED PRUDENT... BANKED MOSTLY ON THE
18Z PARALLEL GFS AND 12Z ECMWF/ECENS MEAN THROUGH MONDAY BEFORE
TRENDING TOWARD A GEFS/ECMWF ENSEMBLE MEAN SOLUTION

 

The issues I have with the outputs isn't so much with the upstream pattern because that normally does correlate with colder weather for the UK its really what happens downstream, I'd like to see a cleaner transition which gets the block in prime position.

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This morning GEFs and ECM anomalies

 

Both have  HP N. Canada ridging SE and linking to HP in southern Europe. Trough NE of  Sacandinavia, linking tenuously to Siberian low and influencing the northern half of the UK  Ridge Alaska and low over the eastern US.

 

Surface analysis HP Greenland and SW of UK with LP to the NE and the eastern seaborsd. On the whole this would bring NW to the UK with the colder air confined to the north,

 

At T360 GEFS still has the Alaskan ridge but slackens the N. Canadian HP link to the Azores and moves the Scandinavian trough east. On the surface this still gives a north/south HP/LP split in the Atlantic but lose the low pressure to the NE.

 

The ECM is slightly different as it keeps the Azores ridge eastern Atlantic and the Scandinavian trough which extends south and east into N. Europe.. This still gives a similar surface analysis as the GEFS.

 

To paraphrase Samuel Longhorne, “pattern change-the reports of my demise have been greatly exaggeratedâ€.

 

Charts weatherbell

 

 

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post-12275-0-86268900-1418807332_thumb.p

post-12275-0-26449500-1418807346_thumb.p

post-12275-0-23621000-1418807357_thumb.p

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Some stunning cold charts this morning from the GFSP. With the Atlantic well and truly blocked, Drawing a bitter N/N/E flow over the UK. 

 

gfsnh-0-240.png?0gfsnh-0-288.png?0gfsnh-0-312.png?0

Those GFS parallel charts are up there with anything I've seen in the internet days, a quite staggering amount of snow possible there, we're talking a foot of snow or more quite widely. Sorry to leave the snow wagon for a moment, but that North Sea storm is also a risk of coastal flooding. The run would be a calamity all round. Probably worst case scenario. But certainly not an outlier except for the depth of the low.

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Those GFS parallel charts are up there with anything I've seen in the internet days, a quite staggering amount of snow possible there, we're talking a foot of snow or more quite widely. Sorry to leave the snow wagon for a moment, but that North Sea storm is also a risk of coastal flooding. The run would be a calamity all round. Probably worst case scenario. But certainly not an outlier except for the depth of the low.

Exeter also highlighting spring tide/coastal issues as a point of watching brief into that period.

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I remnember this time last year and we were grasping onto the the straw of a potent Northerly toppler on Boxing day that was occasionally popping into the odd Op chart. Difference is last year that was the best we could possibly have hoped for (of course, it didn' even happen), this year things are very different heading into the final third of December. With the warming in the strat and prospect of greatly wave activity I would be confident that even if we do miss out in the Xmas - NYD period, I don't think we will have too long to wait afterwards.

I feel the same way. I'm desperately trying to analyse if "it's just me" with rose tinted goggles. Pretty sure last year I too saw hope. Difficult for me to discern if its genuinely looking better. I dare say if the Atlantic went all zonal over the next few days (a possibility) we would all be crying out "ahhh its like last year". I think I will reserve judgement until 48hrs out. However I am of course excited by developments.

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I remnember this time last year and we were grasping onto the the straw of a potent Northerly toppler on Boxing day that was occasionally popping into the odd Op chart. Difference is last year that was the best we could possibly have hoped for (of course, it didn' even happen), this year things are very different heading into the final third of December. With the warming in the strat and prospect of greatly wave activity I would be confident that even if we do miss out in the Xmas - NYD period, I don't think we will have too long to wait afterwards.

 

It is worth remembering as well that the November strat warming and wave1 pressure on the vortex in its natural maturity period has likely terminally weakened it and with a strong E-QBO working against it, literally, on a daily basis, it is and will remain relatively more susceptible than normal. i.e. top strat zonal wind increases are easily and quickly erradicated.

 

Still need a bit of luck from the dice as always though of course!

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Indeed and to be honest I could not see a pattern change at all until a particular GFS run a few days ago caught my attention. If the current output verifies then yourself, Steve M, Tamara will fully deserve the praise that you will recieve.

In fairness Dave you did post that you are now anticipating a pattern change, I remember that post well.  As you say we have to get there yet though.

 

Quote from small part of Ed and Tony's forecast - if it comes off as models are currently showing then it's a tremendous call

 

•Late December and into January is most likely to herald a significant wintry spell, though other major cold snaps throughout the winter are likely as well.

 

Good luck Ed and Tony

BFTP

Edited by BLAST FROM THE PAST
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Post Xmas on the GFS P is an absolute stonker! It is rapidly becoming my new favourite model. The key difference to the 18Z is that the ridging is extends further east which puts the uk right in the firing line rather for heavy snowfall rather than just missing out.

 

 

h850t850eu.png

00Z

h850t850eu.png

18Z

 

The presence of a few shortwaves off the north west coast also aid in setting us up for some really fantastic FI charts if cold and snow is your thing.

 

The 00Z chart above is a chart that even persuaded me to come out of hibernation. (after 10,000 years!)

After catching up on the o/night charts this took my breath away -

 

Folks look to the SW!!!!

Off Portugal is a developing trough,1000 miles long, aimed straight at the Channel. 

 

This in my opinion (if it comes off)  would achieve the following -

 

1) Add 2 feet of snow to the one foot caused by the newly named boxing day blizzard.

2) Promote a strong easterly blast over the UK.

3) Encourage the development of a scandi high when the temperatures in Europe are bitterly cold already.

4) put is into the freezer until March  

 

Apart from that  the odds on it happeneing like that are about 10 to one against!!

 

It would look lilke a combination of 47 and 62!!Am I ramping?

 

Midlands Ice Age

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I remnember this time last year and we were grasping onto the the straw of a potent Northerly toppler on Boxing day that was occasionally popping into the odd Op chart. Difference is last year that was the best we could possibly have hoped for (of course, it didn' even happen), this year things are very different heading into the final third of December. With the warming in the strat and prospect of greatly wave activity I would be confident that even if we do miss out in the Xmas - NYD period, I don't think we will have too long to wait afterwards.

I feel the same way. I'm desperately trying to analyse if "it's just me" with rose tinted goggles. Pretty sure last year I too saw hope. Difficult for me to discern if its genuinely looking better. I dare say if the Atlantic went all zonal over the next few days (a possibility) we would all be crying out "ahhh its like last year". I think I will reserve judgement until 48hrs out. However I am of course excited by developments.

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Can I ask. Why is the operational GFS run different to the average/mean GFS run (sorry if thats not the right words but you know the one I mean. 
I would (ignorantly) think that the operation run would be the average of all the gfs members? that that would be how they come up with the run?

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Can I ask. Why is the operational GFS run different to the average/mean GFS run (sorry if thats not the right words but you know the one I mean. 

I would (ignorantly) think that the operation run would be the average of all the gfs members? that that would be how they come up with the run?

 

The GFS is run at a different resolution to the ensembles and is a separate model, it's a single deterministic model rather than a multi-member probabilistic model. 

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The METO MRF is again very underwhelming with talk of a 'short lived' colder interlude the middle of next week before the Atlantic resumes- Temperatures average or slightly above. Wintry Showers reserved for scotland and higher ground.

Clearly the Exeter pro's are not seeing even the potential for something akin to GFS/ECM between christmas and new year as there is absolutely no caveat involved in their script?

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Exeter also highlighting spring tide/coastal issues as a point of watching brief into that period.

With Exeter looking at a possible low crossing the UK what's your view regarding cold weather between Christmas and new year? do you have any info regarding this aswell as the potential storm?

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With Exeter looking at a possible low crossing the UK what's your view regarding cold weather between Christmas and new year? do you have any info regarding this aswell as the potential storm?

Edit: reply attached to wrong post.

Edited by draztik
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The METO MRF is again very underwhelming with talk of a 'short lived' colder interlude the middle of next week before the Atlantic resumes- Temperatures average or slightly above. Wintry Showers reserved for scotland and higher ground.

Clearly the Exeter pro's are not seeing even the potential for something akin to GFS/ECM between christmas and new year as there is absolutely no caveat involved in their script?

Very worrying that they are not yet being taken in with the eye candy on offer, still a long way out and no doubt they'll be upgrades, downgrades and everything in-between until then but until the pros are singing from the same hymn sheet huge caution is advised.

Edited by Hocus Pocus
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The METO MRF is again very underwhelming with talk of a 'short lived' colder interlude the middle of next week before the Atlantic resumes- Temperatures average or slightly above. Wintry Showers reserved for scotland and higher ground.

Clearly the Exeter pro's are not seeing even the potential for something akin to GFS/ECM between christmas and new year as there is absolutely no caveat involved in their script?

Looking at the ecm ens mean at days 8-15 (of course, usual caveats apply), I have to say I'm very surprised indeed.

Edited by draztik, 4 minutes ago.

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Looking at the ecm ens mean at days 8-15 (of course, usual caveats apply), I have to say I'm very surprised indeed.

The wxtended ecm ens have not been too consistent re the trough hanging on or the atlantic ridge sinking se and a return to Atlantic mobility. The 00z suite certainly in the prolonged trough camp and I'm a bit surprised by knockers last post as he had seen them.

Exeter will be making their call based on ecm extended and mogreps. (Plus other models). I suspect mogreps can't be too keen on the nw euro trough. It could be right but if it isn't, it wouldn't be the first time it was late to a 'cold party'.

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Next updated assessment due later this morning. Last one discussed colder/unsettled/windier possibilities, and they've leaned last couple of days towards high to W, low to E; more veered flow, so broad theme in keeping with 00z output. However, very unwise to over-react to couple of GFS runs at such a range; public f'cast message of anything so pronounced will need much more coherence showing nearer the time in EC & MOGREPS EPS.

Next updated assessment due later this morning. Last one discussed colder/unsettled/windier possibilities, and they've leaned last couple of days towards high to W, low to E; more veered flow, so broad theme in keeping with 00z output. However, very unwise to over-react to couple of GFS runs at such a range; public f'cast message of anything so pronounced will need much more coherence showing nearer the time in EC & MOGREPS EPS.

Lol, not when there's snow to be had Ian. Are any of the MetO models indicating heights building towards Greenland in the next 7-10 days? 

Next updated assessment due later this morning. Last one discussed colder/unsettled/windier possibilities, and they've leaned last couple of days towards high to W, low to E; more veered flow, so broad theme in keeping with 00z output. However, very unwise to over-react to couple of GFS runs at such a range; public f'cast message of anything so pronounced will need much more coherence showing nearer the time in EC & MOGREPS EPS.

 

 

Next updated assessment due later this morning. Last one discussed colder/unsettled/windier possibilities, and they've leaned last couple of days towards high to W, low to E; more veered flow, so broad theme in keeping with 00z output. However, very unwise to over-react to couple of GFS runs at such a range; public f'cast message of anything so pronounced will need much more coherence showing nearer the time in EC & MOGREPS EPS.

 

 

Edited by Hocus Pocus
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this might surprise some of you... but im starting to 'believe' in a colder spell next week...

why?

because of this

attachicon.gif814day.03.gif

which if im understanding this correctly does allow for a block to our west with troughing over scandinavia. this would suggest the ridge is more then a breif transitory event and could lead us into a wintry spell.

 

see my post earlier mushy?

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