Model Output General Discussion

[Nick F]

One thing i've noticed on the 12z GFS, is that it has toned down the strength of the jet coming out of Eern Seaboard across the N Atlantic at the weekend, thus the trough over the E Atlantic off SW Europe is less inclined to deepen and move NE towards the UK bringing milder air ... so the strength of the jet streak coming across the Atlantic later this weekend maybe a deciding factor to whether we see mild air advected NE towards us or kept down across SW Europe.

In the meantime, some excellent opportunities for snow at some point over the next 5-6 days for most, could be alot worse for this early on in winter!

[Snow Queen one]

Geordiesnow i think Steve made that comment a bit tounge in cheek there because he always post info on what the models say for the whole and not just for his area like some. He is a forcaster and knows what he is talking about and prob knows more about where the snow will fall than a lot on here. I am a novice and look for Steves post because they are easier to understand than some others.

[andy_leics22]

One thing i've noticed on the 12z GFS, is that it has toned down the strength of the jet coming out of Eern Seaboard across the N Atlantic at the weekend

As Del Boy once said to Uncle Albert... Don't give me that captain birdseye cobblers!

On a serious note though... I think we shouldn't be paying that much attention to what the models are showing for Monday, we have much more important stuff to get through closer to now. Thursday and Friday could see some nice snowfalls for Eastern and Central areas of England.

[snowmadchrisuk]

As Del Boy once said to Uncle Albert... Don't give me that captain birdseye cobblers!

On a serious note though... I think we shouldn't be paying that much attention to what the models are showing for Monday, we have much more important stuff to get through closer to now. Thursday and Friday could see some nice snowfalls for Eastern and Central areas of England.

If you look Tomorrow Night ,Sometime between 9pm and Midnight that rain is going to turn to Snow over Leicester. Assuming we have a covering by Thursday Morning that is going to keep temps around freezing all day . Snow showers will soon pack in from the East Coast . I prefer to use the 528 line as a guide to weather ppn will fall as Snow , and as you can see below between 6pm and Midnight Tomorrow Night we are clearly covered by the 528 dam.

[johnholmes]

Mmmm.......... What I find disconcerting is the models are showing one thing and people like The Met Office/ John Holmes on Net Weather video forecasting rain with a wintry mix. Surely not?

'fraid so as it was issued over 48 hours ago-no update until hursday when Michael will do Friday on?

[andy_leics22]

If you look Tomorrow Night ,Sometime between 9pm and Midnight that rain is going to turn to Snow over Leicester. Assuming we have a covering by Thursday Morning that is going to keep temps around freezing all day . Snow showers will soon pack in from the East Coast . I prefer to use the 528 line as a guide to weather ppn will fall as Snow , and as you can see below between 6pm and Midnight Tomorrow Night we are clearly covered by the 528 dam.

That is defanitly something to keep an eye on, I fear the PPN will probably have cleared our region by the time the 528 dam gets past us aswell, I could be wrong though.

[johnholmes]

The alert covers the whole of the south i wonder if the south should be split into two halves because that alert obviously doesnt cover somerset/bristol and further west area does it?

try reading he actual Alert - I can't get more specific than naming areas precisely as I have done in the Alert?

[J10]

A much better 12HZ GFS after the 06Hz, and even the UKMO is better than the earlier 06Hz GFS run. At least with these runs today, a chance of some snow shwoers for western areas over the weekend, and perhaps beyond.

[andy_leics22]

try reading he actual Alert - I can't get more specific than naming areas precisely as I have done in the Alert?

John I know you are working your backside off at the moment trying to respond to peoples questions and make forecasts etc... But I don't see 850's or dam line being a problem on Thursday or Friday for Eastern and Central areas. Only where the PPN will end up... If thats the case then surely "Wintry mix" is being a tad cautious.

[johnholmes]

1. The cold air is advecting West from the east , not advecting east.

2. Coastal areas are just as likely to get a proper covering , how far inland does the coastal area cover?

3. In this situation 2-5cm on low ground is too low

4. South east england is NOT southern england , it's south east england.

Can you change those , thanks

thank you Neil for spotting the typo I will go and correct it-I would have been grateful if you had sent me a pm about it as that way I would have picked it up earlier

re your other points, I feel you being a touch pedantic about SE and southern England the Alert makes it quite clear just which parts of southern England; ie central southern England etc

as to points 2 and 3 we will have to agree to differ.

[patrickshere]

Looks like someone turned off the lights.

12z is looking good anyway especially over the next few days. I'd imagine most people will see at least some snow. Looks like radar watching will have to start tomorrow evening!

[I remember Atlantic 252]

Looks like someone turned off the lights.

12z is looking good anyway especially over the next few days. I'd imagine most people will see at least some snow. Looks like radar watching will have to start tomorrow evening!

12Z fantastic -11C minimum for me monday night, that gfs meteociel chart wont exist now as its the parallel, the 6Z suggested much less cold, northerly better as well

[Geordiesnow]

Geordiesnow i think Steve made that comment a bit tounge in cheek there because he always post info on what the models say for the whole and not just for his area like some. He is a forcaster and knows what he is talking about and prob knows more about where the snow will fall than a lot on here. I am a novice and look for Steves post because they are easier to understand than some others.

I also look at Steve's posts with the greatest of respect and he is certainly knows more stuff than i do but i do think his comment that the UKMO is poor is a little ott. If he meant just that 144 chart, then i suppose he has a slight point however it does not look that bad in truthness.

UKMO is a good run but could be better and there are hints the Atlantic might come in.

[johnholmes]

John I know you are working your backside off at the moment trying to respond to peoples questions and make forecasts etc... But I don't see 850's or dam line being a problem on Thursday or Friday for Eastern and Central areas. Only where the PPN will end up... If thats the case then surely "Wintry mix" is being a tad cautious.

kind to comment about how busy I am Andy

wintry mix does NOT occur in the Alert

I assume as someone else has queried it you mean my video broadcast?

if so as I answered that poster it was prepared and sent to NW over 30 hours ago(my apologies to the previous poster I quoted 48 hours-time flies when enjoying oneself!)-nor can we amend it so it has to stand but then as a forceaster one gets used to wishing one had hindsight-the Alert gives my latest view from this afternoon-I have been away for almost the whole of that time so I'm working hard to get up to speed on how the models seem at the moment.

[Lakes Tom]

There appears to be a distinct pattern over the last week in terms of GFS outputs. The 06Z in general, seems to have downplayed the potency of this cold spell, with much doom and gloom on this forum. In contrast, the 12Z and 18Z seem to have hyped up the potency. I suspect that somewhere in the middle lies the true picture.

[johnholmes]

IF I get time this evening I'll do an update to the blog I've been running-I'll try and be reasonably specific on areas where I think snow is more likely-and then all of you!! we are getting close to T+24-use Extra or NMM and put the will it snow Guide to the test.

let me know your results but it would be helpful if you posted all the criteria you used?

[grab my graupel]

Let's get back on topic please, folks :lol:

[TEITS]

Stuning 12Z and if that verifies im sure some of us wouldn't give a monkeys what happens afterwards.

With so much to concentrate on im going to focus on the E,ly which has certainly upgraded these past 48hrs. Here is the latest +48 fax chart and the forecast that would go with this is a real blast to the past.

http://www.meteociel.fr/ukmo/fax/fax48s.gif

Simply put on Thurs you will find showers turning to snow and becoming more frequent during the day. During the evening the snow showers would become heavy prolonged and merge into longer periods of snow. The areas most likely to see the heaviest falls are Lincs, Norfolk, Notts, Leicestershire, Northants, Cambs. Derbyshire.

During friday the snow showers will continue.

Only later in the day will the snow showers beging to fade away.

Now this forecast is based not only on the model runs but previous experience of similiar synoptics. Obviously due to the nature of showers some will be hit harder than others and some will experience snowfalls outside the area I mentioned. However 2-5cm of snow is likely over a wide area but falls of 20-30cm cannot be ruled out!!

Edited December 15, 2009 by THE EYE IN THE SKY

[Thundery wintry showers]

ECMWF is just coming out now, and the easterly for Friday supports the GFS 12Z solution with a pronounced ENE flow backing NE over the southeast and some pretty impressive thicknesses- plenty of snow showers there I'd imagine, and a few hugging the coast in the northeast.

The ECM's handling of the northerly is still to be determined later in the run, but so far it looks nothing like the GFS 06Z.

[eyeofthestorm]

ECM 120hrs

[casparjack]

ECMWF is just coming out now, and the easterly for Friday supports the GFS 12Z solution with a pronounced ENE flow backing NE over the southeast and some pretty impressive thicknesses- plenty of snow showers there I'd imagine, and a few hugging the coast in the northeast.

The ECM's handling of the northerly is still to be determined later in the run, but so far it looks nothing like the GFS 06Z.

The T+120 looks a little worrying, cant get T+144 yet...

[East Herts Snow]

ECM at +144hrs....

http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=0

Low slips South, not quite sure on this run yet.

Edited December 15, 2009 by North Londoner

[chrisbell-nottheweatherman]

ECM 120hrs

A cold NW wind for northern areas plus potential battleground scenario for the south?

[on the coast]

ECMWF is just coming out now, and the easterly for Friday supports the GFS 12Z solution with a pronounced ENE flow backing NE over the southeast and some pretty impressive thicknesses- plenty of snow showers there I'd imagine, and a few hugging the coast in the northeast.

The ECM's handling of the northerly is still to be determined later in the run, but so far it looks nothing like the GFS 06Z.

Very good chart. Look at that High come south.

[casparjack]

The T+120 looks a little worrying, cant get T+144 yet...

...now the T+144 looks much better, the warmer uppers appear to have been repelled!