Model Output Discussion

[Gowon]

Posted Yesterday, 18:35

Secret Society, on 28 February 2010 - 18:29 , said:

i stopped looking at GFS about 3 years ago.

dont know why people are still even consider it a model.

Totally agree, GFS is renowned for illogical synoptical swings ( mostly at Bank Holidays and Weekends I might add ). See it move back in line on tomorrows 12z run when human input is restored.

I Rest my case !!

Yep, but I still view it for details like precipitation and temps.

Edited March 1, 2010 by Higrade

[Frosty.]

You have to love the gfs model, another completely different FI from the last 2 runs so instead of mild weather mid month it's back in the freezer, total tosh in fi from run to run but nice to see all those blues though. :lol:

[Bristawl Si]

Coldageddon run from GFS 12Z, very wintry run indeed

http://www.wetterzen...s/Rtavn3362.png

http://www.wetterzen...s/Rtavn3121.png

Pretty much inline with brickfielders thoughts for the first half of March at least.

http://www.meteociel...20-21.GIF?01-17 - Looks like bitterly cold nights this weekend with some very cold dewpoints being dragged in

Those charts are 2 weeks away! The model runs only 2/3 days ago were showing a quite snowy spell for southern england this coming Friday and weekend and that's been downgraded significantly, so i really cannot take much notice of charts for 2 weeks time.

Extract from Ian F's blog seems to indicate a drier, normal temp spell coming up soon. In the meantime a 'wintry feel' for this weekend in some parts, although not as wintry as models were progging a couple of days ago.

"A cold easterly windy will be very noticeable and whilst many areas will remain largely dry, some hill snow is likely at times from Wednesday onwards in the SW and elsewhere; perhaps a chance of more significant rain, sleet and snow in East Anglia by the weekend. However, after a continuation of this cold, blocked anticyclonic pattern, there's a hint of temperatures starting to return to the norm within the latter part of this coming fortnight."

[snowfish]

You have to love the gfs model, another completely different FI from the last 2 runs so instead of mild weather mid month it's back in the freezer, total tosh in fi from run to run but nice to see all those blues though. :lol:

It's a better run overall from the previous one - depending on whether you want 'spring' or a last 'sting in winter's tail' lol! This thursday will see the fun and games begin if those charts manifest what do you think?

[Thundery wintry showers]

Interesting- the UKMO/ECM showing a low moving down the North Sea pulling in a cold easterly or north-easterly and GFS having none of it, I assumed the Euros would fall into line with the GFS but it's the other way around with GFS showing something more akin to this morning's Euro runs and UKMO continuing the same theme.

Yes disappointing for southeastern areas now for saturday, a cold, overcast and raw day expected alot different feeling than today thats for sure.

http://www.wetterzentrale.de/pics/Rtavn1201.png

A cold overcast and raw day is only likely if (1) there are fronts about or (2) the airmass is stable with relatively warm upper air but cold surface air. Neither of those conditions are present on the GFS 12Z, the precipitation outputs show convection, the temperature outputs show a fair differential between daytime and night-time temperatures, and therefore the most likely result would be sunny intervals and wintry showers.

Again, I doubt that such a chart would be interpreted by anyone as "cold overcast and raw" if it was progged to occur prior to the 1st March.

UKMO goes for something more pronounced than GFS- would probably bring a snow cover to much of East Anglia and the SE- but only for 36 hours, so by T+144 we'd be seeing dry sunny weather for all and a thaw in the sun in snow-covered areas.

[Geordiesnow]

Again, I doubt that such a chart would be interpreted by anyone as "cold overcast and raw" if it was progged to occur prior to the 1st March.

I seen your earlier comment which would appear to be directed at me as i said this morning's UKMO at 120 hours (i think it was) looked dull and i still stand by that. The airflow was northerly but it did not came from a cold source so a dull cloudy day looked like what that chart was showing, i would of said whether its the 1st of March or the 1st January.

Obviously with colder uppers, the GFS would be more convective, albeit only over a small area as the high is too close. Personally the GFS 12Z in the short-medium range is not a snowy run except for EA and the SE and that only for a short amount of time aswell. Its an equivilant of a toppling northerly and we all know toppling northerlies gets dismissed as a waste of time in this thread.

I suppose upgrades in terms of the cold and snow could still occur if the models start to strengthen that trigger shortwave, i doubt it would be anything we had a few days ago but it could make any easterly shot a little bit more long lasting than it is currently.

[SP1986]

Should clear by saturday night though with a harsh frost setting in, a very impressive cold arctic plunge into europe and just clipping the far southeast/south, i wonder if future runs will trend that back towards us for the weekend.

http://www.wetterzentrale.de/pics/Rtavn13810.png

http://www.wetterzentrale.de/pics/Rtavn1322.png

http://www.wetterzentrale.de/pics/Rtavn13817.png

Based on experience and having seen the following days temperatures as usual I'm pretty sceptical. I'm currently amassing a nice body of evidence against the GFS 'temperature debacle'. Results will be issued when the cold weather is over, as to be fair it is possible to get -6C. But with daytime temperature recovering back to 9-10C after in this instance is highly unlikely, even with the sun, unless the air is extremely dry.

As for the run, were certainly not out of the cold run, in fact I'm struggling to even find any evidence from the charts that any mildness of any form will come anytime soon (give or take odd 9-10C days like today)

[Thundery wintry showers]

I seen your earlier comment which would appear to be directed at me as i said this morning's UKMO at 120 hours (i think it was) looked dull and i still stand by that. The airflow was northerly but it did not came from a cold source so a dull cloudy day looked like what that chart was showing, i would of said whether its the 1st of March or the 1st January.

Obviously with colder uppers, the GFS would be more convective, albeit only over a small area as the high is too close. Personally the GFS 12Z in the short-medium range is not a snowy run except for EA and the SE and that only for a short amount of time aswell. Its an equivilant of a toppling northerly and we all know toppling northerlies gets dismissed as a waste of time in this thread.

I suppose upgrades in terms of the cold and snow could still occur if the models start to strengthen that trigger shortwave, i doubt it would be anything we had a few days ago but it could make any easterly shot a little bit more long lasting than it is currently.

It wasn't aimed at your post at all- in fact I think I missed your post altogether- it was more addressed at those who were already posting along the lines "anything cold is just dull and raw and wet at this time of year and of no use to anyone roll on Spring".

Re. the UKMO's T+120 northerly this morning you had a strong case for evaluating that chart as "dull", for the airmass source was indeed heavily modified. This evening's UKMO goes for a less modified source, but there is still scope for changes in either direction. However while the GFS is not a snowy run (I doubt it would even give much to East Anglia and the SE) and has less potential than UKMO 12Z I don't see anywhere being particularly dull/overcast from it as Eugene suggested.

This evening's ECM will be interesting but we still IMHO have a good day or two to go before details can be firmed up one way or another.

[kold weather]

Looks pretty decent in the 12z GFS, the best thing of all is the models have somewhat moved away from the cloudy option today as the high never quite seperates from the high feature that is present to our east which keeps slack winds over our area and keeps the clundy muck further north.

[cooling climate]

Based on experience and having seen the following days temperatures as usual I'm pretty sceptical. I'm currently amassing a nice body of evidence against the GFS 'temperature debacle'. Results will be issued when the cold weather is over, as to be fair it is possible to get -6C. But with daytime temperature recovering back to 9-10C after in this instance is highly unlikely, even with the sun, unless the air is extremely dry.

As for the run, were certainly not out of the cold run, in fact I'm struggling to even find any evidence from the charts that any mildness of any form will come anytime soon (give or take odd 9-10C days like today)

Time and again you posted that temperatures would not get as low as the GFS

was suggesting yet time and again the temperatures were lower.

Are we to see a rivival of the easterly over the weekend and into next week

perhaps.

The blocking signature shown by the models further out has been there for a while

now although the GFS has gone off on its merry way at times.

[BarnetBlizzard]

It wasn't aimed at your post at all- in fact I think I missed your post altogether- it was more addressed at those who were already posting along the lines "anything cold is just dull and raw and wet at this time of year and of no use to anyone roll on Spring".

Re. the UKMO's T+120 northerly this morning you had a strong case for evaluating that chart as "dull", for the airmass source was indeed heavily modified. This evening's UKMO goes for a less modified source, but there is still scope for changes in either direction. However while the GFS is not a snowy run (I doubt it would even give much to East Anglia and the SE) and has less potential than UKMO 12Z I don't see anywhere being particularly dull/overcast from it as Eugene suggested.

This evening's ECM will be interesting but we still IMHO have a good day or two to go before details can be firmed up one way or another.

I havn't seen the UKMO yet but the GFS seems to have alot of potential. If the high cover Northern England can move itself a bit further north, it allows these easterly winds with very cold uppers to come screaming in. If those winds came in that would mean lots of snow showers which would flow a fair bit inland.

[TEITS]

Time and again you posted that temperatures would not get as low as the GFS

was suggesting yet time and again the temperatures were lower.

.

Yes I would agree with you.

Some of the extremely low GFS min predictions this winter have been based on the GFS attempting to model where snowfall will occur and how much will fall. Now we have to cut the GFS some slack here because its virtually impossible to get this right and even higher resolution models will struggle. A good example is when Benson experienced over 20cm of snowfall, the temp dropped to -16C by 9pm. Now 20-30cm of lying snow will cause temps to drop alot lower compared to 0-5cm of lying snow if you have clear skies, light winds.

Overall this winter i've found the GFS temp predictions to be fairly accurate and if anything the max temps progged during the Dec cold spell were around 2-3C too high!

Back to the models and I see some of the colder members have reappeared in the ensembles.

http://charts.netweather.tv/ensimages/ens.20100301/12/t850Cambridgeshire.png

So based on the GFS/UKMO/GEM upper temps of -10C might just briefly clip into E Anglia/SE before moving S. Nothing compared to the E,lys the models were suggesting and what happens after remains uncertain to me.

[TonyH]

Based on experience and having seen the following days temperatures as usual I'm pretty sceptical. I'm currently amassing a nice body of evidence against the GFS 'temperature debacle'. Results will be issued when the cold weather is over, as to be fair it is possible to get -6C. But with daytime temperature recovering back to 9-10C after in this instance is highly unlikely, even with the sun, unless the air is extremely dry.

Such a diurnal range in late winter/ spring is fairly common here.

For example in february 2008 had min -7c to max 11c. The frost survived in the shade that day!

[phil nw.]

Such a diurnal range in late winter/ spring is fairly common here.

For example in february 2008 had min -7c to max 11c. The frost survived in the shade that day!

Indeed and with these dewpoints such low mins. are very possible,

http://www.wetterzen.../Rtavn13810.png

Unless of course GFS is overdoing those too .

Edited March 1, 2010 by phil n.warks.

[phil nw.]

ECM a little earlier tonight suggests the chilly theme continuing for later in the week.

The High building close by but allowing a brief Easterly .

http://www.wetterzentrale.de/pics/Recm721.gif

Perhaps something Wintry from the North Sea low later

http://www.wetterzentrale.de/pics/Recm961.gif

http://www.wetterzentrale.de/pics/Recm1201.gif

Then settling down but still cold but bright for many,frosty nights.

http://www.wetterzentrale.de/pics/Recm1441.gif

http://www.wetterzentrale.de/pics/Recm1681.gif

I would settle for that for early Spring,fresh and bright by day after frosty starts.

[Thundery wintry showers]

Looks like the ECM would keep the cold dry sunny weather going for most northern and western areas but that easterly around T+144 looks like it would deliver a fair amount of snow to parts of East Anglia and the SE, so it can't be written off yet but looks unlikely to affect northern and western Britain regardless of what happens.

[January Snowstorm]

Overall this winter i've found the GFS temp predictions to be fairly accurate and if anything the max temps progged during the Dec cold spell were around 2-3C too high!

Yes very true it forecast mins of -7 for Ireland in December and we got to -10

It seems to remain cold and frosty for the foreseeable though I would expect daily high's to nudge up under strong sunshine. We had a severe frost here last night which the sun had burnt off by 9am!!

[nick sussex]

In terms of cold upper air the UKMO looks the pick of tonights models, although the ECM looks similar the UKMO draws the flow from much further east and would certainly bring some snow showers into the east and se.

The ECM's later output looks settled but not particularly cold with that slack flow off the continent, its not really possible to develop cold surface pools at this time of year with that set up, so a slow moderation in temps would occur. Generally into March northerlies provide the best wintry conditions with inland convection developing some heavy wintry showers, easterlies are initially okay early in the month as long as theres a good pool of very cold upper air.

[karyo]

In terms of cold upper air the UKMO looks the pick of tonights models, although the ECM looks similar the UKMO draws the flow from much further east and would certainly bring some snow showers into the east and se.

The ECM's later output looks settled but not particularly cold with that slack flow off the continent, its not really possible to develop cold surface pools at this time of year with that set up, so a slow moderation in temps would occur. Generally into March northerlies provide the best wintry conditions with inland convection developing some heavy wintry showers, easterlies are initially okay early in the month as long as theres a good pool of very cold upper air.

Yes, for eastern/southeastern areas, there is some interest for a time. However, I find the later ECM output disappointing as it doesn't have the slightest hint of a northerly (unlike the gfs). As you say, northerlies are the best source for wintry weather in spring and that's just what we need now!

Karyo

[nick sussex]

Yes, for eastern/southeastern areas, there is some interest for a time. However, I find the later ECM output disappointing as it doesn't have the slightest hint of a northerly (unlike the gfs). As you say, northerlies are the best source for wintry weather in spring and that's just what we need now!

Karyo

Agreed I've often enjoyed many a decent snowfall off a March northerly, you need a bit of luck when the snow falls in terms of keeping the cover but I remember back in Sussex in 2006 several days when snow fell just before dusk so managed to keep it till the morning. Actually I prefer northerlies than easterlies into March as theres always that inland convection compared to the deep winter months when its bone dry for much of the country and the bbc stick up Carol Kirkwood stuck on a hill close to the North Sea!

I wouldn't rule out a northerly just yet as the ECM previous runs did hint at this so still a chance.

[Whether Idle]

Well, it has to be said that IMBY there is a high (>65%) possibility of snow falling in this part of Kent over the period Friday-Saturday. Minus 11 uppers, a 25 Knot NE wind and surface temperatures around 3c max and sub zero dewpoints. All models show this possibility with UKMO and NOGAPS seemingly being keenest on it. A slight shift in the position of the high futher nortwest towards Iceland and the passage of the low southwards on Friday and it could turn into the fourth big dumping this winter. Will need watching. . The potential is there.

[bluearmy]

http://www.meteociel.fr/modeles/ukmo2.php?ech=120&carte=2000

T120 FAX shows the snow risk for the se lies with the following occlusion rather than the cold front. knowng how reliable these occlusions can be re even being there when verificion arrives, i wouldnt 'hold your breath'.

[Thundersquall]

An example of why we can't trust charts in the T+300's!

18Z T+312:

12Z T+324:

Edited March 1, 2010 by Thundersquall

[snowray]

lol!

Hope you had a nice time....Yeah, it's a bit like a stuck record - however, what a winter it's been! One for the memory vaults eh?! :blink:

easterly may be coming northerly would be awfully fine.

Everyone gets excited at the very first sign.

We've all been here so many times, you cannot help but larf...

I think I'll wait for the old pub run, but before I'm gonna get me barf!

Very good! Thats been the story for NW Kent/SE London this winter, too far East, North, near miss or too marginal (apart from the top of Biggin Hill of course).

I could be wrong, but since someone asked about Mr S Murr earlier, well I think he has gone off in disgust, I remember him getting very excited a fair few times earlier this winter, and it certainly looked as if we were going to be in the so called "honey pot" a couple of times but alas poor Yorick it was not to be, or not to be. :wacko: Then he got some uncalled for criticism I think from some quarters, maybe the wind up merchants that were loitering on here for quite a while this Winter but have now disapeared without a trace.

Anyway, 18z certainly seems to be moving towards the Euro's this evening, ECM, UKMO, NOGAPS then V GFS and JMA, maybe thats indicative of something. Of course if the high could slip just say 100/150 miles further North/Northwest as Tamara mentioned, even 50 miles would be a start, then things in here would start hotting up a bit. The alternative is that the extreme East of Kent may cop the lot again. Longer term, looking cool and dry, so Sunny days will be most apreciated by many I'm sure.

Edited March 2, 2010 by snowray

[john mac]

Morning everyone

Interesting outouts fromthe 0z this morning, would i be right in saying that there would be snow on the ECM12z t96 for the southeastern corner of the UK?