General Model Output Discussion

[BarnetBlizzard]

This easterly following the low has upgraded dramitcally in the last 24 hours. It seems that the further north you are the longer the easterly is, but the further south you are the more potent it is.

http://www.netweather.tv/index.cgi?action=nwdc;sess=

Edited December 28, 2009 by BarnetBlizzard

[snowking]

18z has a little feature moving in across the south-eastern quarter of england too on friday, as shown by the vortical lift:

http://www.wetterzentrale.de/pics/Rmgfs877.gif

http://www.wetterzentrale.de/pics/Rmgfs907.gif

http://www.wetterzentrale.de/pics/Rmgfs937.gif

http://www.wetterzentrale.de/pics/Rmgfs967.gif

Its subtle changes to the flow of the LP which make little features like this start to crop up.....we have to remember this is only one run but this is what just about anyone with half an ounce of common sense has been suggesting what would happen - the GFS backtrack of epic proportions

I'd suspect things may even head a touch further south than shown on the 18z

For anybody who may have suggested that the GFS would stick to its guns and prove the euro's and the canadian model wrong, I think you may have to swallow a little humble pie here...

SK

[TEITS]

does the precip also end up further south?? at the moment it still looks to get as far as the north midlands. will this be modified back south ??

loved rob M on N24 21:30.

At this rate im even beginning to wonder if it will reach further N than the Wash!

Im basing this not only on the trend but also previous experience of such synoptics.

[Optimus Prime]

Well we had 12c reaching the far south, that is now replaced by 7c. THE biggest shift in output we've ever seen.

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Well we had 12c reaching the far south, that is now replaced by 7c. THE biggest shift in output we've ever seen.

I think that's still the case

[Optimus Prime]

I think that's still the case

No that's the far SW. 12c was as far inland as Southampton or Winchester. Now those parts are at 7c and 5c respectively.

[Geordiesnow]

I must say, its nice too see the that the GFS has now fully trended with the ecm regarding the low, even the GFS 12Z run was not fully there but the 18Z completes the jigsaw.

Anything after 100 hours is most certainly to change but it would seem we will have a low developing in the easterly flow which is ashame in one way as i would prefer a nice clean easterly but in another way, its a good thing as if you are near the low then some persistent PPN is likely as this run shows NE Scotland in the firing line.

I don't think the low will be any further south from here on in although i suppose stranger things have happened.

[BarnetBlizzard]

No that's the far SW. 12c was as far inland as Southampton or Winchester. Now those parts are at 7c and 5c respectively.

Ive never seen such a large range in temp at such a short distance! Certainly is very marginal in some places, really wish i was in wales now

[kent]

good - no horrid wet snow and big dirty puddles and instead a cold convective easterly for several days. what would you prefer?

At this rate this LP system could miss the uk completely.

[Weather-history]

Wasn't some people earlier today, saying how GFS can't be so wrong at this short timeframe?

[Snowaddict]

I must say I like the look of the 18Z NAE at T+18

Also, an absolutely stunning 18Z GFS Operational out to T+168 from what I can see.

Also, relatively deep cold from the east moving westward over open water... Localised heavy falls possible in convective situations.

SA

Edited December 28, 2009 by Snowaddict

[TEITS]

Wasn't some people earlier today, saying how GFS can't be so wrong at this short timeframe?

I can't think who that might be.

+168 is much better on the GFS compared to the ECM due to the block remaining over Greenland rather than backing W. Hopefully you will see why very shortly as the next frames come out.

[bluearmy]

GFS and ECM looking almost in general agreement around T192 - T240. mind you, GEM was there 12 hours earlier.

[Tom D]

Well well... the GFS is looking very good for snow in the E Midlands/East Anglia and SE England on Thursday, providing there's precipitation around.

The medium term outlook is looking very cold too. A quite stunning set up right out to FI.

[bluearmy]

latest 18z NAE takes the 0c isotherm up to a similar point to the 18z by midnight tomorrow. about 100 miles north of the 12z ecm.

[Optimus Prime]

The Pub '18z' Run ends with a perishing easterly and -3c maxima. An easterly which in most winters since 1997 would have been cool and drizzly.

[Liam J]

gfs has the low further south, but also the ppn touching the borders, albeit quite light and with -6 or -7 850's over here then it would certain be snow falling.

tomorrow will be bitter, with easterly winds strong and temps here around 1c or 2c at best and with no sun the temp will not rise much at all due to the cloud, i suspect another ice day in places as its -4 to -8 accross cumbria now

proper winter feel best wrap up well, and blizzards further south oh dear not good at all....

[Thundery wintry showers]

The theme for this coming week: an area of rain, with sleet & snow on its northern flank, stalling over the Midlands midweek and possibly getting into northern England (though GFS/UKMO are backing away from that possibility), then retreating south. Further north, sunshine in the west and wintry showers in the east, the showers falling as snow in all areas of E Scotland and NE England from Thursday onwards.

It's notable that the easterly of 17th/18th December was of the sunshine-and-showers variety, and the upcoming one looks highly likely to be the same. All too often we get a burst of easterly winds and nothing but stratocumulus trapped underneath an inversion- December 2002 had an extreme example of this- but so far the easterlies just haven't looked like doing that. The main reason is that the easterlies are being sourced from Arctic or Siberian sources rather than from the dry, stable heart of central and south-eastern Europe, which is also what happened with the easterly incursions of the winter of 1965/66 (a winter that often came up in Glacier Point's analysis).

[Iceni]

Why are there hardly any posts, with a week or more of cold weather? Have people become totally fed up with the GFS and not even bothering to look at it?

I've taken a look and it seems we're in for 10 or more days' snowfall in the east. Perhaps they've taken one look and hit the supermarkets panic-buying in places like Wales.

[Guest North Sea Snow Convection]

Taking the current model outlook into account, plus the outlook for January c/o not just Net weathers Glacier Point, but now the likes of Sir Rob and other METO officials and other weather agencies who are also now suggesting that Jan is on course for a freeze-up, then we really have a definitive winter on our hands in every 20th/21st century historical sense of the word. I am not suggesting a 62/63 comparison but against the low expectations held for so long by so many in terms of what the UK winter has been supposed to be able to deliver, then what more is needed to put that into question??

It hasn't happened yet, as we are barely a third of the way through the season - but the evidence is stacking up day by day.

[Snow storm]

GFS very exiting for next Thursday night/Friday morning in the South

[kold weather]

GFS and ECM looking almost in general agreement around T192 - T240. mind you, GEM was there 12 hours earlier.

I think the broad evolution actually is a good one compared to some of the runs earlier this morning on the 06z from the GFS. However I'm willing to bet any money any Greenland high will last longer, eventually the PV will try and sink southwards and exactly where is whats uncertain, however by that point the state of the jet means we either keep a cold flow from the north thanks to the PV, or we end up in a cold HP set-up...the third option is the -ve NAO becomes too far west based...in which case a possible snow set-up followed swiftly by a milder SW flow...but for now I think thats rather unlikely, any NAO is probably going to be centered right over Greenland.

Regardless I think odds are decent for another sustained cold spell for now...

[nick sussex]

We will see, obviously this is a dig at me. Normally people would be posting the GFS PPN charts to illustrate tomorrow, obviously the model has backtracked from its aggressive Northward forcing of the Low.

Regardless of what any model shows at this stage regarding the low i still think it's open to more changes, the models at the moment seem to be taking turns with north and then south shifts in the precip and judging by the bbc they have as much idea as the rest of us. I think it's perhaps time for everyone in the UK to start nowcasting! to be honest i'm bored of this low now and will be happy once it's off the scene!

[TEITS]

We will see, obviously this is a dig at me. Normally people would be posting the GFS PPN charts to illustrate tomorrow, obviously the model has backtracked from its aggressive Northward forcing of the Low.

Sorry Ian I didn't mean my post to come off as a dig, just a bit of light hearted banter.

Nice to see the ensemble mean agree with the models.

http://91.121.94.83/modeles/gens/run/gens-21-1-72.png?18

[Guest North Sea Snow Convection]

The theme for this coming week: an area of rain, with sleet & snow on its northern flank, stalling over the Midlands midweek and possibly getting into northern England (though GFS/UKMO are backing away from that possibility), then retreating south. Further north, sunshine in the west and wintry showers in the east, the showers falling as snow in all areas of E Scotland and NE England from Thursday onwards.

It's notable that the easterly of 17th/18th December was of the sunshine-and-showers variety, and the upcoming one looks highly likely to be the same. All too often we get a burst of easterly winds and nothing but stratocumulus trapped underneath an inversion- December 2002 had an extreme example of this- but so far the easterlies just haven't looked like doing that. The main reason is that the easterlies are being sourced from Arctic or Siberian sources rather than from the dry, stable heart of central and south-eastern Europe, which is also what happened with the easterly incursions of the winter of 1965/66 (a winter that often came up in Glacier Point's analysis).

Based on this and especially your earlier posts, I think that you are underplaying the snow convective risk for East Anglia, the east midlands and the south east for the end of this week.

Edited December 28, 2009 by North Sea Snow Convection