Winter Model Discussion 12Z 15/02/13 onwards.

[Penrith Snow]

Well I feel your answer just illustrates the problem with the BBC/Met O forecasts.

I have learn't that the models are useless when it comes to predicting convection and this is especially true with E,lys. If the output today remains unchanged then you don't even need to look at the projected precip charts from the models to know more than light snow showers will occur. The term light snow showers is only correct for Wed/Thurs but that isn't the case for the end of the week into the weekend when heavier showers would develop especially across E Anglia/SE.

Again just illustrates my point of over reliance on computer models these days. Remember a recent snowfall when you stated the SW was at greatest risk and I disagreed. Well the reality was the SW actually experienced mild temps whilst others enjoyed snowfall.

Just add im not having a go at you but I get frustrated at times because forecasting instinct has disappeared due to this over dependance on forecast models.

Post of the day.

Over reliance on computers is a problem in modern live and no less so in weather forecasting.

I read about the Air France air crash recently and it was the over reliance on the computers that led to the crash, the computers told the pilots they were going to fast yet in reality they were about to stall, old experienced pilots would have 'felt' the planes speed but the young pilots in control thought the computer must be right.

Srrty off topic but we ignore human experience at our peril.

With regards to the easterly the models always predict Cumbria will stay dry being west of the Pennines but in reality we have some of our best snowfalls from these situations ie Feb 2009.

Andy

[Ice Day]

Cold a little slower getting here, but all's looking good at 120

[Cecil Hogmanay Melchett]

is that a trough at 126h on gfs06z?

[IDO]

Yes changes already with the initial snow risk mid-week pushed north:

0z: 06z:

[IDO]

...and the colder uppers profile shifted north by the end of next week:

0z: 06z:

Edited February 16, 2013 by i'm dreaming of...

[manutdmatt1986]

More widespread snow further North on this run due to the high being further North. Poorer for snowfall in the South East. No point getting hung up on such small details at this point though.

[fergieweather]

Post of the day.

Over reliance on computers is a problem in modern live and no less so in weather forecasting.

I read about the Air France air crash recently and it was the over reliance on the computers that led to the crash, the computers told the pilots they were going to fast yet in reality they were about to stall, old experienced pilots would have 'felt' the planes speed but the young pilots in control thought the computer must be right.

Srrty off topic but we ignore human experience at our peril.

With regards to the easterly the models always predict Cumbria will stay dry being west of the Pennines but in reality we have some of our best snowfalls from these situations ie Feb 2009.

Andy

Human experience is precisely what modifies the raw model data at Exeter. If we merely relied on raw output it would be a different matter... we don't. 12Z GM (modified!) post-Weds due imminently.

[UV-RAY]

...and the colder uppers profile shifted north by the end of next week:

0z: 06z:

Do we ignore the 06z today then?

[chris55]

Friday would feel bitter, in the strong south easterly wind.

[Methuselah]

Not at all sure that I agree with all this 'over-reliance on computers' argument...Unless I'm wrong - far from unheard of! - computers merely churn-out results of a vast array of simultaneous equations: the very same equations that armies of people armed with pen, paper and slide-rules would otherwise be required to solve?

Who recalls the Met's monthly forecasts from the '70s and '80s; the ones that used to be completely wrong, by the time the mid-week update was issued?

Whatever, it's looking ever more likely that, come the weekend, cold conditions and probably snow will be a major feature of the forecasts...

[TEITS]

This run is going to result in even greater convection around 160 plus as the winds veer from SE to E then ENE,ly.

[NickR]

Friday would feel bitter, in the strong south easterly wind.

THose winds would be Ely rather than SEly - remember the wind direction doesn't exactly follow the isobars.

[Liam J]

Ignoring any snow potential at this range the 6z is a very cold run, bitterly cold with notable wind chill and any thoughts of spring would seem like an age away.

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=156&mode=0

[Ice Day]

162 and it will feel bitter in a strong easterly

[shaky]

Do we ignore the 06z today then?

Following the ecm then?

[chris55]

Regardless of snowfall amounts, which are always going to be near impossible to get right at this range, this chart sure is great February winter fair.

Edited February 16, 2013 by chris55

[snowking]

Wow this is going to be a long week if people will insist on following the GFS precipitation charts to a tee with every new run that comes out - you are setting yourselves up for a lot of distress!

Good runs this morning, still very similar to yesterday, good agreement on the 500mb flow, but once again we need to wait to see what the 850 profile will look like. UKMO/GFS looking very good, but the ECMWF, in truth, only really develops any meaningful convective potential for around 24 hours on so before we see the -8's and -6's mixed out - that said, it's a huge improvement on yesterday! Still though these details will continually change in the coming days.

In terms of the convective argument - TEITS I completely agree, but Ian has alluded already to the fact that the Met Office do edit raw output to increase inland penetration of showery activity, but as we all know there is no way we will know what will happen WRT convection until much closer to the time. Last week at +120 things looked good for a convective easterly following the LP, but given the changes to the upper profile and the track/shape of the low, this all got watered down. Hopefully this won't happen this time, but as Nick and Ian B have cautioned this morning, I'm not happy to look particularly closely at convective potential until much closer to the time

I havnt had a chance to look at the ECM EPS mean precipitation output yet, but once I get a chance later ill see if I can post a couple of frames - with the added caveat that the raw model output does underestimate convective potential

SK

[Frosty.]

This is a very good looking Easterly on the Gfs 06z, quite a lot of snow showers coming well inland, exciting times ahead next week.

[chris55]

THose winds would be Ely rather than SEly - remember the wind direction doesn't exactly follow the isobars.

I always forget about that, strong easterly winds then,

[TEITS]

Solid from the NOGAPS aswell.

[Ice Day]

This is a very good looking Easterly on the Gfs 06z, quite a lot of snow showers coming well inland, exciting times ahead next week.

Oh dear, TEITS is in the bullseye again!!!!

[Liam J]

Quite a prolonged cold assault on the GFS this morning, strong easterly winds giving many days of sub zero windchill & penetrating frosts then factoring in the potential for snowfall things could get interesting. If this was happening within the next few days then it would likely trigger a cold weather alert pretty high up on the Met Office scale.

Some quite classic looking winter charts it has to be said whether they verify or not. Look how far the Atlantic is being kept at bay!

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=186&mode=0

Edited February 16, 2013 by Liam J

[Frosty.]

Oh dear, TEITS is in the bullseye again!!!!

LOL it will be less marginal this time, bitter winds from the east, no sign of mild returning.

[The Weather Dragon]

Not to much to get excited about from the overnight/morning runs. Cold - YES, Severe Cold - NO. Snow for some - YES. Nationwide - NO. Significant lack of cold pooling over Continental Europe. Expect further modification upwards of 850's and further downgrades. Advice - to follow the MET O on this one to avoid dissapointment.

[fergieweather]

Latest from UKMO as far as Thurs sees little change to previous: in summary, "Risk of a few light wintry showers on exposed eastern coasts, increasing risk of loc moderate wintry showers in the S/SE by Thurs".