Model Output Discussion

[Eugene]

Extremely low confidence of an atlantic breakdown from this T+120 hrs fax thats for sure, very difficult to see any powerful atlantic LP systems on there

http://www.wetterzentrale.de/pics/brack4.gif

[cooling climate]

Cheers for your support TEITS much appreciated.

I will say no more about mid to long term (FI), my thoughts are well known.

Anyway it could very well be an exciting few days to come with a channel low

thrown in for good measure.

Unfortunately the 18z run has the track of the low Monday just about right so

if the low exists at all it will almost certainly be on a different track to what is

being shown tonight.

[Eugene]

Well out to the limits of high res and its still cold.

http://www.wetterzen.../Rtavn18017.png

Who cares if it turns mild after 25th of February anyway as by March 1st officially winter will be over and the stats will come in to show this winter as being one of if not the coldest winter in over 25 years

Edited February 17, 2010 by Eugene

[kold weather]

What an odd FI run, the GFS blows the Atlantic up and develops huge and very slack low pressure system with at one point 4 seperate centers!

One of the most strange FI runs I've seen in a very long time that one, I'd be doubtful it comes off quite like that, synoptically its super rare stuff I'd imagine, esp after the type of winter we've had...it even blows up a brand spanking new Polar vortex for us...in March!

Very mild is what I;d say the 18z FI is, but yet more evidence for a big change coming which is hard to ignore.

Edited February 17, 2010 by kold weather

[SP1986]

As squish says on TWO a stunning GFS 18Z run so far, people moaning about no cold on the models must need their heads read really they do.

http://www.wetterzen.../Rtavn10217.png

The problem is the GFS has been doing a lot of this recently, putting out grossly overexaggerated minimums, which in most cases don't occur. I've come to the conclusion that these instances of the GFS doing this are probably an overreaction to a signal. The setup just doesn't lend to cold of that order, as widespread or severe as shown.

[Nick L]

The problem is the GFS has been doing a lot of this recently, putting out grossly overexaggerated minimums, which in most cases don't occur. I've come to the conclusion that these instances of the GFS doing this are probably an overreaction to a signal. The setup just doesn't lend to cold of that order, as widespread or severe as shown.

Sorry Stephen, but you have repeatedly posted this during the winter and you have failed to give evidence to prove it. The GFS today OVERstated temperatures by a few degrees here, so it works both ways.

[LomondSnowstorm]

The problem is the GFS has been doing a lot of this recently, putting out grossly overexaggerated minimums, which in most cases don't occur. I've come to the conclusion that these instances of the GFS doing this are probably an overreaction to a signal. The setup just doesn't lend to cold of that order, as widespread or severe as shown.

Not sure about that. In fact this morning which was progged to be around -2C turned out to be -5C! It may not be accurate in terms of minima but not necessarily on the low side.

[Weather-history]

I will say no more about mid to long term (FI), my thoughts are well known.

They are but there is little to back it up, all I see is a trend to become milder around the 25th Feb on the models. The models have got it wrong this season and had problems but are they wrong this time? We will find out nearer the time.

[Geordiesnow]

I think the GFS temps you see are for rural locations generally rather than city centre temps. -10 is certainly possible in clear skies, light winds and a decent snowcover i'm sure.

18Z is quite a stonking run, snow over a large area of the UK although the southern edge of that band will be of rain i would of thought. As ever though PPN charts will change so don't get too attactched over it!

There is a slight trend that we may see milder conditions via a low to the SW of us but more runs are needed as per usual but i feel if things do turn milder, it will still be wet in places as it often is at this time of year.

[Weather-history]

I thought Winter ends 20th March, Vernal Equinox.

Official record keeping, winter ends on the last day of February.

I'm always baffled why this is always asked because I thought the seasons were taught at school and the seasons were always 3 month periods. At least that was what I was taught.

[ChartViewer]

18Z is a run for cold lovers...However is out of tune with all other Models.....

The Mid term sees SW muscling in and a Milder theme showing in the Models ECM/UKMO etc,,,,,,

Suspect a jet picking up and moving North (the jet will eventually fire up) will drive those Milder te mps to our shores in early March

Regards,

CV

Edited February 17, 2010 by ChartViewer

[J10]

TEITS - when do the Beeb forecasts start to use the latest fax charts? Latest forecasts (incl the south west's own Ian Fergusson) suggests South Midlands, SE Wales, East Wales and Central and W.Midlands as main area of snow, with BTL area just on the 'borderline' so to speak.

Latest forecast from both the GFS and the NAE have an increased risk of snow for Wales, as the precipitation moves further north than originally thought.

[Eugene]

Looking at the GFS 18Z ensembles on meteociel there is an increasing amount of cold runs in FI now, HP could form to our south, northeast, northwest or north and push over or near the british isles keeping it cold

[kold weather]

Yep there are a fair few runs where another LP cuts off from the main Atlantic low which keeps the UK in the cold for longer, in fact quite a few runs now keep the cold till the 27-28th...

[MR EXTREMES]

lol i really dont know what more i can add,

other models pretty much all in agreement.

with the gfs 18z,

which dare i say i never really had much faith in i dont know why that is though,

but the others i dont worry to much about them there pretty realiable lately its always a possiblity a cold trend could build.

but i dont see it its not clear cut and very complicated ofcoarse those who love winter like myself would cherish this run but i all honesty i think you could end up rather dissapointed.

gp said recently how messy it all was its not easy for a cold setup with our current setup because everything is hampering everything else,

just like the shortwave recently that ruined our true easterly i think now its make or break and even with tonights 18z i still not convinced one bit.

Edited February 17, 2010 by badboy657

[TEITS]

Im getting a sense of deja vu in the model out at the moment. The charts at +168 are exactly the same as they were a few days ago at this timeframe. However when I now look at those charts for this weekend I don't see mild SW,lys but instead a possible snow event.

So just maybe once the +168 charts reach +96 the LP may take a similiar track to the LP at the weekend. I just don't buy this ridge of HP from the S and the mild SW,lys via LP tracking NE. For me I see a continuation of what we're already seeing i.e further possible snow events with a jetstream being much further S than normal.

[kold weather]

My main worry is we get the jet too surpressed and thus we miss the snow events possible for early next week and instead we stay cold and dry only for the Atlantic to stem roll in with very little 'fun' at all to be had, its a very real risk IMO and we'd miss out what is IMO a really great chance for a big snow event for even the south looking at the current models...so hopefully the 18z is a start of a trend for Monday's possible system and it doesn't trend any further south.

[Sno' problem]

Well it seems that the trend is continuing, with the 00z seeming to be a bit of an upgrade, not only for Friday morning's chances for a dusting, but Monday is looking great for the Southern coastal regions of the South East.

So you may be heading down to the South coast in perfect time Kold!

Edited February 18, 2010 by Sno' problem

[David-kig]

a much better gfs 00z following met office forecast. cold throughout fo midlands northwards with milder interludes for southern areas as low pressure tries to attack from the south west and is unsucessful. much better hopingfor more up grades to come. looks like a wintry bag this weekend esp monday

[andymusic]

Amazing GFS 00z - cold right through till March for everyone - with some good snow prospects too

[Eugene]

ECM 00Z looks very good also not much tweaking for it to be like GFS 00Z, GEM 00Z is great UKMO very good upto T+120 hrs, not total model agreement but as ever the models are struggling like they have done this winter, i'm calling for it to stay cold in the midlands north at least.

[Eugene]

ECM T+144 hrs is not a mild chart at all even for the south, its showing colder 850`s than right now infact and its cold/foggy out now.

http://www.meteociel.fr/modeles/ecmwf/run/ECM0-144.GIF?18-12

[TEITS]

Well incredibly the first signs from the models that mild SW,lys might not occur. The 0Z GFS might be an outlier but importantly it becomes an outlier within the higher resolution of the model run. So this means if the 06/12Z continue with the same trend then you often find the ensembles slowly agreeing.

The reason for the difference in the model output, and the GEM is also included in this, is what happens to the low at +168. Rather than a ridge of HP to the S we see this being supressed but we also see a splitting of the LP with the SW transferring SE. This allows a ridge of HP from the N bringing an even colder N/NE,ly flow. I have no reasons to doubt this evolution because this has been a common theme all winter!

Back to the possible snow event on Monday and to be honest alot will depend on your location whether you feel the LP is ideally placed. For my location the LP is actually too far S so I miss the precip. However any further N will mean locations to the S will only see rain. Remember ideally you want to be just N of the centre of the LP.

[BrickFielder]

There is a bit of disagreement between the models on what will happen today. Net weathers NMM charts which I think are initialized with GFS data are suggesting a further north track with snow only reaching central areas into the evening.

Comparing this to the bbc forecast this morning and the timing is very different. In a way we stand more chance of snow if the system does come through during the evening, so it might be a good thing if the NMM model was right for snow lovers.

The question then is which models are right. My hunch looking at forecast precipitation for now and actual radar suggests the bbc might be closer to the truth. It all depends on which was initialized with the latest data. All eyes on the radar and 06z GFS then.

[Polar Continental]

Still a rather cold and unsettled outlook from the models this morning with the threat of snow at times.

Rather cold outlook.

The GFS in the short term is looking at some cold nights, and rather surprisingly several widespread ice days over the next week, I would think the model is expecting freezing fog to persist, to achieve this at this time of the year.

I know some mention the GFS tends to under estimate temperatures; I have found on average it is fairly accurate on the whole, plus or minus 1 degree.

Cold nights.

Cold days

Regarding snow, during daylight hours today, over the south, I think this will be limited to high ground in Devon, further north, again high ground only, low ground rain or sleet. Though tonight as the colder upper air digs in, I think some lower ground in central areas will get some snow for a short time before it clears away.

Todays maximums.

Precipitation area.

Colder upper air spreading south.

Rain turning to snow tonight as colder air digs in.