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Model output discussion 8th Feb - Cold for now, but then what?


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I'm going for a fleeting Northerly and colder air early next week then back to normal - just can't see the support at the minute for anything colder..ECM , GFS 12z op and the METO aren't saying anything decent really!! 

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Evening All- ive been offline for a week taking a little break- monitoring the progress of the strat mainly- Things are homing in nicely now on the second SSW of the season ( a final warming

the possibility of a prolonged cold spell towards late November the possibility of a prolonged cold spell towards early December the possibility of a prolonged cold spell towards mid December the poss

Rather disappointing that the obsession over cold and snow excludes some fascinating weather over the next 72 hours. This is the deepening low, not yet even formed. It is due to begin to develop in th

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4 minutes ago, Ali1977 said:

 just can't see the support at the minute for anything colder..ECM , GFS 12z op and the METO aren't saying anything decent really!! 

The GEFS tells a different story longer term with increasing support for a much colder spell during early / mid March..support has grown today as the earlier charts I posted show.

Edited by Frosty.
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5 minutes ago, Frosty. said:

The GEFS tells a different story longer term with increasing support for a much colder spell during early / mid March..support has grown today as the earlier charts I posted show.

I would agree that the GEFS have trended from mild to average. Cold would be stretching it ;-) 

Glimmer of hope? GEFS, each run, showing negative AO and NAO. Too many runs to be based on nothing.

That said, doesn't guarantee cold for the UK. Puts you in the game with a good hand though.

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Despite some internal fluidity the overall pattern remains much the same as recent runs with good agreement between the models and as far as NOAA is concerned high confidence.

So strong vortex N. Canada/Greenland with associated troughs running down eastern N. America and SE over Southern Greenland. with ridge GOA. With the jet exiting N. America south of the Atlantic trough in the upper westerly flow, and with the Azores being less influential than of late, then an unsettled period is indicated with systems tracking west-east with temps varying around the average but possibly in general slightly above. This doesn't of course exclude transient intervals of more wintry Pm air and as as always the det runs will add the details,

ecm_eps_z500a_5d_nh_11.thumb.png.60ba40b0ec1447dfb2b551611a42c103.pnggefs_z500a_5d_nh_41.thumb.png.8c012bf02aa344e03c0610cee78fddd4.png610day_03.thumb.gif.9d3aefd7f5ba098a1f6093718d5cdc33.gif

There are some slight changes within the 10-15 period. The GOA ridge retrogresses, the vortex slips a little south tacking the Atlantic trough with it which allows some ridging in the region of the UK with some positive anomalies east of Iceland. This has the effect of backing the upper flow but perhaps, with the HP again becoming influential, the periods of unsettled weather will be more inclined to favor the north. Temps generally still a little above average.

gefs_z500a_5d_nh_61.thumb.png.e05c7e009205fe338317246f199b0340.png814day_03.thumb.gif.f48ea2b1efb5316878f23f7ee17a4a06.gif

Edited by knocker
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Looking at the short term - a cooling trend after tomorrow, with uncertain developments come Thursday, with the models showing quite a deep low tracking straight through the centre of the country, and developing in situ, could be a nasty little feature with gales wrapped around its southern flank, and cold air on its northern flank which should bring a fair bit of snow down to quite modest levels by the end of the day I would imagine - so a surprise snowfall may be in the offing for a lucky few, a transient shortlived affair, but one to one.

Friday is forecast to be a pleasant day for many, some decent sunshine which has been absent for a good week or so now, which will be good given how gloomy things have been for much of this month might even see some frost for the first time in nearly 2 weeks.

Weekend looking unsettled and very windy, and quite chilly feeling especially in the north, with the azores high becoming less of an influential player, indeed might we see another low/frontal feature track through the centre of the country to end the month, with colder air behind, very plausible.

After a winter virtually devoid of any sustained unsettled windy conditions bar the brief period run up to and over christmas, winter 16/17 looks like ending on a very unsettled note.

Edited by damianslaw
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A quick word on the GEFS to start. No major change in the 5-10 ranges, which means still some transient amplification as it proceeds with the upstream changes mentioned yesterday evening. Then in the later period,  with these changes in place, i.e.the retrogression of the GOA ridge, vortex slipping south and retrogression of the trough in the western Atlantic, we have the Atlantic becoming more meridional with height rises in the east with ridging in the vicinity of the UK

gefs_z500a_5d_nh_61.thumb.png.866c872cf479a967969e6371583e9fb3.png

Back at the ranch sees the Thursday depression 979mb over the borders bringing rain and quite strong winds with snow in the northern quadrant over high ground. This quickly moves away as a couple of shallow secondary lows track SE just north of Scotland before the next fronts arrive on Friday associated with a slow moving deep depression south of Iceland

gfs_ptype_slp_eur3_17.thumb.png.0e0f815735fee5c9db1864ac8f7ed492.png

From this position we move into amplification mode with next upper trough deconstructing to the west as the Azores ridges in mid Atlantic. this evolves into a cut off upper low to the SSW with an an accompanying large surface area of low pressure as the HP  ridges NE under pressure from the east bound energy.

gfs_z500a_natl_30.thumb.png.bb92010b297b445a6ba3bf734b79e733.pnggfs_ptype_slp_eur3_35.thumb.png.2e59c907567043fc3ffeb4ccf40dbbf7.png

We end up in this position at T240 with strong WAA over the UK. I's all a bit messy to be honest and one gets the impression the models are struggling, perhaps with the emerging different signals.

gfs_z500a_natl_41.thumb.png.2a65f1e5b72daf750043221f1bb2a309.png

Edited by knocker
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Needless to say the ecm does not follow the gfs towards the end of the run. It has the main low pressure centre in the North Sea with the ridge to the west at T192. It then has brief ridging over the UK before the next Atlantic fronts arrive. So in a nut shell disagreement on the handling of the amplification.

ecm_t850a_5d_natl_11.thumb.png.7df8b56153e71fa639f33e217c898f21.png

Edited by knocker
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The ext EPS this morning is following the pattern adjustment already described. With the GOA ridge expected to retrogress and the vortex to slip south the Atlantic becomes more meridional with the trough becoming very negatively tilted and some ridging adjacent to the UK with some positive anomalies east of Iceland. Portending some more settled weather with temps a little above average as the flow backs SW or even SSW  Hopefully that should lift the mood in here..:)

Edited by knocker
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The Gfs  Develops the low and brings some quite windy weather to central parts and then towards the East  some places could be hit with 90+kph  winds  then as it drifts east   possibly 100+  Edit   Met going for 70 to 80mph  across the spine of the country 

48-289UK.gif

51-289UK.gif

Edited by weirpig
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The 6z fails to develop things to the north, and remains unsettled throughout. I would expect it to be a bit of an outlier amongst the ensembles later. Not much more to add really - unsettled until the end of the month at the very least, alternating cold and mild.

Rmgfs144sum.gif

Very wet in the far NW (over 100mm of ppn forecast in the next 6 days), so the risk of some flooding issues there. Drier the further south and east you head.

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Very quiet in here on the 12zs, not much happening after the initial excitement on Thurs - if a block can form in the right location around day 9 the v cold air is still hanging around Northern Scandy and wouldn't take much tapping into - although I think the main reason for a quiet forum is the distinct lack of comment from the METO on poss SSW implications for the UK - these may be none I guess!!

Edited by Ali1977
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On 2/21/2017 at 17:22, johnholmes said:

Rather disappointing that the obsession over cold and snow excludes some fascinating weather over the next 72 hours. 

EDIT: I did not realise that there was a designated thread for Storm Doris - I was responding to John's post above. Well, it's 90% model related but if the moderators want to move John's and my posts across to that thread, that's fine with me.

TRACKING STORM DORIS

@johnholmes I completely agree John - it looks like Storm Doris is going to pack quite a punch. I shall add some of the charts that you requested + a few others. I will edit this post and add several more later. If you would like any others, please send me a PM and I'll see what I can do. Please feel free to copy my post and then edit it with your comments. Your huge career experience is respected by many members on this forum and we would appreciate your analysis and further comments. The storm is predicted to be at its strongest around lunchtime on Thursday as it moves out into the North Sea having crossed southern Scotland and northern England. I checked the other models and they now all have a similar track, strength and timing  If anyone can find any small changes in the fine detail, then please post it for the sake of completeness. I note that there will also be very strong winds in the English Channel. I will check the tides too shortly just in case we need to look out for a North Sea storm surge (UPDATE: none predicted - see edit 2 below). I note that Nick F has published the wind warnings on NetWeather - I'll leave it to him to add further details, which I'm sure he'll do..

Firstly the pressure charts at 6 hours intervals using the GEFS 12z output (control run):.

       T+30 Wed. Feb 22nd 1900              T+36 Thur. Feb 23rd 0100               T+42 Thur. Feb 23rd 0700             T+48 Thur. Feb 23rd 1300            T+54 Thur. Feb 23rd 1900 

gens-0-1-30.png  gens-0-1-36.png gens-0-1-42.png gens-0-1-48.png gens-0-1-54.png

        T+60 Fri. Feb 24th 0100               MetO Fax Valid 0000 Thur. Feb 23rd          MetO Fax Valid 1200 Thur. Feb 23rd           MetO Fax Valid 0000 Fri. Feb 24th

gens-0-1-60.png         20170221.1700.PPVG89.png              20170221.1700.PPVI89.png                20170221.1800.PPVJ89.png   

GFS T+48 Thur. Feb 24th 1300 10m Winds kmph      ECM T+48 Thur. Feb 24th 1300 850 hPa Winds kmph

          gfs-14-48.png?12                                      ECM4-48.GIF

      Net Wx-MR Wind Gusts (mph) Thur 0900                       Net Wx-MR Wind Gusts (mph) Thur 1200                    Net Wx-MR Wind Gusts (mph) Thur 1500 

           nmmukgust.png                                        nmmukgust.png                                nmmukgust.png 

Net Wx-MR Mean Surface Winds (mph) Thur 0900      Net Wx-MR Mean Surface Winds (mph) Thur 1200      Net Wx-MR Mean Surface Winds (mph) Thur 1500 

           nmmukwind.png                                        nmmukwind.png                                nmmukwind.png

 

EDIT (1):  RIVER FLOOD WARNINGS - LOW RISK ON THURSDAY (source: Environment Agency) 

Forecast for Tuesday 21 February 2017 to Saturday 25 February 2017

The forecast flood risk across England and Wales for today is VERY LOW, increasing to LOW at times over the next four days. Persistent rain may lead to some river flooding across northern and central parts on Wednesday, with isolated property flooding and travel delays possible. Further rain on Thursday over the north of England in association with Storm Doris may lead to similar river flooding across the north-east of England, but less likely over hills where precipitation is expected to fall as snow. On Saturday, further spells of rain may bring flooding to Wales and the north-west of England. There is a small chance that flooding in the north-west of England could affect parts of communities and lead to significant travel delays.

EDIT (2):  NORTH SEA FLOOD WARNINGS AND TIDAL SURGES - None predicted for Thursday (source: National Oceanography Centre - Tidal & Sea Level Facility, as at Tuesday 1930)

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

UPDATE:   @Gael_Force says in his post below;  "You mention the GEFS charts in your post are the ensemble mean. It is actually the control run that appears instead"

Thanks for pointing that out - I'll leave the control charts and change the title. Actually at only T+48 there are very small differences (5mb in central pressure and also small variations in the individual members). Here's the mean chart (not sure if this can be frozen - ie: it may update with each run, so I'll replace it each time with the chart showing Thur 1300:

GEFS ens mean 0z T+12 for Feb 13th 1300

  gens-21-1-12.png

Edited by Guest
Correcting typos and to ensure that all the links and charts work properly.
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I think that there is interest in storm Doris even from the snow freaks that are regulars on here like me, could well be a fair bit of snow in fact on the northern flank of the low as it moves east, along with strong winds that will produce blizzards in places, mainly in Scotland and along the borders with difficult driving conditions on some of the higher routes. 

 

 

51-780UK.GIF

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3 hours ago, johnholmes said:

Rather disappointing that the obsession over cold and snow excludes some fascinating weather over the next 72 hours.

It's not being ignored John. As is usual for named storms, it is being discussed on the dedicated thread.

@Bring Back1962-63 You mention the GEFS charts in your post are the ensemble mean. It is actually the control run that appears instead.

Edited by Gael_Force
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9 hours ago, mb018538 said:

The 6z fails to develop things to the north, and remains unsettled throughout. I would expect it to be a bit of an outlier amongst the ensembles later. Not much more to add really - unsettled until the end of the month at the very least, alternating cold and mild.

Rmgfs144sum.gif

Very wet in the far NW (over 100mm of ppn forecast in the next 6 days), so the risk of some flooding issues there. Drier the further south and east you head.

Looking very December 2015'ish

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