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Model Output Discussion 01/09/17


phil nw.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

I think the issue for the Met Office and other organizations which make LRFs is in terms of La Niña .

If its a weak La Niña that helps colder prospects , a strong one would be a problem . 

You also have to factor in the MJO , that has much less impact with a strong La Niña. At this point I’d keep an open mind about December’s prospects .

Theres also the issue of coupling which John Hammond alluded to in his excellent blog.

I do think however that the UK needs to make the most of the current set up which is reluctant to stick the PV over Greenland . It’s quite unusual to see the PV so disorganized and reluctant to set up in its favourite place at this stage of the Autumn.

Edited by nick sussex
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Posted
  • Location: Kendray,Barnsley,God's county.
  • Weather Preferences: Snow freezing fog heatwave thunderstorm
  • Location: Kendray,Barnsley,God's county.

Its ecm/ukmo vs gfs again, gfs was wrong for cold prospects just a few days ago so I'm sticking with ecm/ukmo this time, go and have a long walk off a high cliff gfs nobody likes you.

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

Much better GFS in the mid term

gfsnh-0-198.png

Certainly gives us something to build on and for us, miles away from the 18z

Edit-

HP being sheared in towards Scandi, prolonging the cold- almost a stellar chart for areas towards E coast

gfsnh-0-228.png

Edited by CreweCold
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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
54 minutes ago, CreweCold said:

Much better GFS in the mid term

gfsnh-0-198.png

Certainly gives us something to build on and for us, miles away from the 18z

Edit-

HP being sheared in towards Scandi, prolonging the cold- almost a stellar chart for areas towards E coast

gfsnh-0-228.png

Looks very similar to ECM 12z a very good start to the day another northerly airstream too for the weekend seems likely, unusual for the models to latch onto this evolution a fair bit out an eyebrow is subtly raised that's for sure. There is even some back edge snow on GFS 00z for the south at day 6! Interesting how quickly things can fall into place, but also the other way around I'm feeling more intrigued this time around. 

image.thumb.png.547c97a9d30b058c6483fac1dddef9c3.pngimage.thumb.png.c1950573cc454bf355a80943ab3a1001.png

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Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
1 minute ago, Daniel* said:

Looks very similar to ECM 12z a very good start to the day another northerly airstream too for the weekend seems likely, unusual for the models to latch onto this evolution a fair bit out an eyebrow is subtly raised that's for sure. There is even some back edge snow on GFS 00z for the south at day 6! Interesting how quickly things can fall into place, but also the other way around I'm feeling more intrigued this time around. 

image.thumb.png.547c97a9d30b058c6483fac1dddef9c3.pngimage.thumb.png.c1950573cc454bf355a80943ab3a1001.png

The ensembles are all over the place so yes, caution required as ever.

Will be interesting to see the ECM days 8, 9 and 10 charts to see if they corroborate the GFS and GEM version of events.

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL

Big ECM coming up, if it follows the GFS and GEM the UK may have a "good" chance for the first real country wide cold spell for 3 years - only late November so it won't be very cold but snow and frost for most not out of the question, those on high ground in North or and East may get some decent falls if charts prove correct!! 

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Posted
  • Location: Camborne
  • Location: Camborne

Firstly given the huge differences between last night's anomalies I'm viewing the detail from next weekend onwards with suspicion and filed under 'this is what the models say this this morning'.

Today and tomorrow. Not going to attempt the detail but the general synopsis is a shallow low is en route eastwards across Scotland this morning dumping a fair bit of rain and also some quite strong winds.It will soon clear by this afternoon. Elsewhere all areas will be in a mild, moist, SW/W airstream so cloudy with perhaps some sunny intervals. Tomorrow sees another more intense low arriving from the SW so rain quite quickly into the west and Scotland where it will again be heavy and windy.

PPVA89.thumb.gif.419231f53eb227f990eb26989881d357.gifPPVE89.thumb.gif.bec7de2613165a52bf941e1c2772513c.gifPPVI89.thumb.gif.30e8f50f9c06fff7777f837d329ca3c4.gif

By 12 on Wednesday the low has tracked into southern Norway and at this point it might be useful to get an idea of the pattern to see where we stand vis the evolution for the rest of the week and the weekend. There is a large positively tilted upper trough, into which one that has nipped around Greenland has phased, aligned Scandinavia-mid Atlantic with the delineation between the cold/warm air quite obvious.

gfs_ptype_slp_eur3_11.thumb.png.d15ea9bba3890d3d10a48aace0813978.pnggfs_z500a_natl_11.thumb.png.410ccb53cd636ad762829f4c8968968a.pnggfs_t850a_natl_11.thumb.png.adfe5575bc229965761453d81f06865e.png

As can be seen from the above chart a complex surface area of low low pressure lies to the west of the UK and by midday Thursday a depression has become more organised 974mb west of Ireland with the front already impacting N. Ireland and Scotland with snow on the high ground. This moves quickly north east to be quickly followed by another which could also bring some snow to the highlands  All courtesy of the main trough which drifting slowly east, under pressure from the HP amplifying in the west, as also is the warmer and moist air.

gfs_ptype_slp_eur3_15.thumb.png.187abdac6c52a45641fb8cfd6585563f.pnggfs_ptype_slp_eur3_19.thumb.png.1614bd59444ec9d1ea3157d1b0d53e78.pnggfs_uv500_natl_19.thumb.png.f8fbdef43e07ddecf9ba061ca899ea93.png

So over saturday the front and waves are much further south over southern England as they track east and with the surface wind veering north west the much colder air covers the UK as the ridge nudges in from the west. But this is extremely transient as the incoming energy from the west quickly squashes the ridge as the next trough and fronts arrive by Monday 00 bringing heavy rain, perhaps significant snowfalls in Scotland and even higher ground further south accompanied by gales,

gfs_ptype_slp_eur3_23.thumb.png.18407feeef6c75a47870c8750d1ccae1.pnggfs_ptype_slp_eur3_29.thumb.png.c4d970c1abef1861b4044c256f1e454a.pnggfs_uv500_natl_29.thumb.png.ccfb7206306f12208580d6a64dc17c6b.png

 

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Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

Cold set of ens from GFS after the milder peak a steady fall behind the front then a cold and changeable picture, night frosts in clear spells and even the possibility of hill snow down south.

IMG_2881.thumb.PNG.a85b9700ec38f636e4b8a9ef28521791.PNG

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Posted
  • Location: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth

gfsnh-0-216_fye1.pngECH1-216_nhr4.GIF

 

Fairly evident which one most would prefer. T216 so detail will change but if the overall theme is to be believed then a train of wind and rain from the west looks unlikely. 

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Posted
  • Location: North East Cotswolds, 232m, 761feet ASL
  • Location: North East Cotswolds, 232m, 761feet ASL
1 minute ago, That ECM said:

gfsnh-0-216_fye1.pngECH1-216_nhr4.GIF

 

Fairly evident which one most would prefer. T216 so detail will change but if the overall theme is to be believed then a train of wind and rain from the west looks unlikely. 

The ECM also looks full of reload potential , no PV around southern Greenland or NE Canada should allow further WAA incursions into the Arctic, the more of these the more south the colder air generally moves. All looking rosey this morning for us coldies, keep an eye on the longer range METO for guidance is say!! 

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Posted
  • Location: Camborne
  • Location: Camborne

Although the ecm continues to deconstruct the main trough quicker than the gfs at T120 thus it has the HP amplifying quicker and a different orientation of the main trough, they are not, given the fluidity of the pattern, not a million miles apart over the weekend and the beginning of next week.

Thus over the weekend the UK is in a fresh north westerly airstream possibly even gales force on exposed coasts, with squally wintry showers particularly in the north, then some some brief ridging before the next system arrives from the west.

ecm_mslp_uv850_natl_6.thumb.png.4012376688f0aeb1c59f6e8a6ba21102.pngecm_mslp_uv850_natl_7.thumb.png.95c4e6bdd330456dcd7f36a048520bae.pngecm_mslp_uv850_natl_8.thumb.png.c5588747252e1c271ced339b0bb3ffdb.png

Edited by knocker
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Posted
  • Location: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth
12 minutes ago, knocker said:

Although the ecm continues to deconstruct the main trough quicker than the gfs at T120 thus it has the HP amplifying quicker and a different orientation of the main trough, they are not, given the fluidity of the pattern, not a million miles apart over the weekend and the beginning of next week.

Thus over the weekend the UK is in a fresh north westerly airstream possibly even gales force on exposed coasts, with squally wintry showers particularly in the north, then some some brief ridging before the next system arrives from the west.

ecm_mslp_uv850_natl_6.thumb.png.4012376688f0aeb1c59f6e8a6ba21102.pngecm_mslp_uv850_natl_7.thumb.png.95c4e6bdd330456dcd7f36a048520bae.pngecm_mslp_uv850_natl_8.thumb.png.c5588747252e1c271ced339b0bb3ffdb.png

Hi knocker. I agree/can see all of what you have said apart from "before the next system arrives from the west." Genuinely interested in this bit as I am not seeing this from this morning runs apart from on the frames on GFS at t300 plus. What am i missing? Not being "funny" as i have much respect for your analysis and posts:) 

Edited by That ECM
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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

What’s going on here? The models are having shocking ‘agreement’ GEM really takes amplification to town with a stonker of a Greenland high. 

C435A920-7DC0-4AD6-BCBB-51733C2CB98F.thumb.jpeg.2f341b30f252fe1f47714c6417c31553.jpeg

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Posted
  • Location: Purley, Surrey - 246 Ft ASL
  • Weather Preferences: January 1987 / July 2006
  • Location: Purley, Surrey - 246 Ft ASL

Yes - feels like a big shift in the medium term over the last 12 hours. Now starting to see some good agreement on mid Atlantic height rises; with these stretching up into Greenland. The relocation of the PV over towards Scandinavia also leads to significant troughing developing in this area. Looks to be some interesting developments in the strat thread as well.

I would give the chance of a North Easterly air stream affecting us in the next 14 days as maybe 30-40% - hopefully we will continue to see small upgrades over the next few days. 

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Posted
  • Location: Camborne
  • Location: Camborne
9 minutes ago, That ECM said:

Hi knocker. I agree/can see all of what you have said apart from "before the next system arrives from the west." Genuinely interested in this bit as I am not seeing this from this morning runs apart from on the frames on GFS at t300 plus. What am i missing? Not being "funny" as i have much respect for your analysis and posts:) 

I can't post the charts to illustrate what I mean but if you look closely on that T168 chart you can see a little system just south of Iceland. This little low and front tracks south east into Ireland and England during Monday as it phases into the circulation in the western quadrant of the main low to the east leaving a cold northerly airstream in it's wake. I could have explained this a bit better. :)

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Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

As long as charts like this don't start appearing, I'll be happy! :D

gfsnh-2013121800-0-156.pnggfsnh-0-192.png

PV overload in that winter (13/14). Incessant wind, catastrophic floods. December 2015 was of course the crazy record breaker that is unlikely to be repeated any time soon. 
Thankfully this looks a million miles away at present. Interesting output for sure!

Edited by mb018538
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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
1 hour ago, chris55 said:

Cold set of ens from GFS after the milder peak a steady fall behind the front then a cold and changeable picture, night frosts in clear spells and even the possibility of hill snow down south.

IMG_2881.thumb.PNG.a85b9700ec38f636e4b8a9ef28521791.PNG

This is backed up by ECM snow chart, which maintains snow interest for Northern and Western areas, but also has a temporary period of snow for central southern areas on Saturday morning (the blink and you'll miss it type, though).

Edited by Man With Beard
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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
1 minute ago, johnholmes said:

This morning ECMWF-GFS both show a meridional flow into the UK, Ridging/+ve heights in the Atlantic up to Greenland with very marked troughing over the UK and then down into Europe. The NOAA version last night did not show this so a sitting on the fence time until all 3 are very similar for a couple of days. 

Yes i think thats a good call JH, GFS/EC both bring a PM airflow moving in at the weekend- meto forecast mentions showers turning wintry across the hills of NW England Friday, doesn't go further than that but the text appears to back up the GFS/EC 00z operationals this morning.

Hopefully Pennine areas will see some snow over the weekend- at this stage i suspect elevation will be important but fascinating times for those of a cold persuasion. :)

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL

Well despite the NWP output moving in the right direction for coldies the beeb forecast this morning was pretty underwhelming!!

They seem to be backtracking after yesterdays evenings mention of a colder end to the week now they say they are not so sure!!

Anyway, the GEFS 00z have certainly 'flipped' to a colder scenario- pretty big change from the 18z GEFS !

 

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