Model Output Discussion

[kev238]

Well- completely different to the last run. I will be interested to see where this sits in the ensembles. The track of the low on Monday is crucial to prospects for the rest of the week.

[Guest FireStorm]

If there is no model agreement, the middle ground of both scenerio's is likely to be the outcome.

So a copy of this week then lol

[Higher Ground]

I have been wondering if the models have been somewhat flummoxed by the SSTA patterns.

http://weather.unisy...e/sst_anom.html

In very simplistic terms, it seems to me that if a low pressure is likely to take a path along the lines of that currently projected by the GFS for Monday, then the colder than average SSTA's along its path would imply the tendency would be for it to take a path even further south than the models would "normally" project, other things being equal. Whereas if it were likely to take a path towards the NW of Scotland, the warmer than average SSTA's it would encounter would imply the reverse i.e. a tendency for it to take a path even further north. Hence the vulnerability of such a set-up to small initial changes/perturbations resulting in large variations in low tracks.

This is just speculation, an invitation to someone with more expert knowledge than myself to suggest if the SSTA pattern might be of any relevance?

Hmmm just seen GFS +114: not sure i'll get any replies to this as i fear it may be buried under a stack of over-excited snow ramps! (Edit: far south of England snow ramps; obviously now risk of being too far north even here in Midlands, but can't complain too much given we've done fairly well already...)

Edited February 19, 2010 by Higher Ground

[cooling climate]

Now if this was next Tuesday and the t114 chart was for the following morning

there would be a lot of very happy southerners (including myself ) on this thread.

LOL just seen the UKMO 12z run and it has a 975mb low sitting over western

Scotland at t96.

Edited February 19, 2010 by cooling climate

[kold weather]

Quite possibly not a bad call Firestorm!

A total mess though in regards to whats going to happen, the ensembles will make interesting viewing. There were actually a lot of the 0z ensembles suggesting this evolution, but then that number dropped away on the 06z ensembles.

Probably can't look beyond 36hrs as of now I feel!

[nick sussex]

From snowfest to rainfest, thats the difference between the GFS and UKMO. The GFS is a big upgrade compared to the 06hrs run, the UKMO a downgrade, in fact the UKMO at 96hrs looks very poor in comparison with snow prospects greatly reduced for the whole of the UK. I'd put FI at 72hrs and place the rest of the output in the bin!

[Guest FireStorm]

I have been wondering if the models have been somewhat flummoxed by the SSTA patterns.

http://weather.unisy...e/sst_anom.html

I Dont think all the models data take into account SSTA's to a degree where they could be vastly influenced or El Nino and La Nina would greatly affect the model's too (newbie thought though)

[kev238]

Just to add to the whole pot the NAE model at 42 hours shows snowfall across much of Central England and Wales stretching down towards the Bristol and Cardiff area. It will be interesting to see if this remains consistent as it moves towards T +6

Edited February 19, 2010 by kev238

[Iceberg]

Very much a similar fujiwhara effect as you get on canes, which LP centre will become dominate south al la GFS or north al la UKMET GM ?.

Or do they merge in the centre. ?

Do the tracks assuming north or south wins shift north or south ?.

This doesn't look like one of those occasions where a middle ground is reached, one will likely win and become dominent, for selfish reasons I think it should be the south as this give me a snow fest.

[karyo]

Now if this was next Tuesday and the t114 chart was for the following morning

there would be a lot of very happy southerners (including myself ) on this thread.

LOL just seen the UKMO 12z run and it has a 975mb low sitting over western

Scotland at t96.

I was relatively relieved to see the 12z gfs placing the lows further south but the UKMO is rather disappointing. It takes everything further north and it has been consistent in doing so.

Karyo

[Deep Snow please]

Can someone tell me where to find the models as soon as they come out.

[LomondSnowstorm]

Not sure what to believe from this. From a personal point of view I feel the UKMO would be better for my own personal snow chances but it is hard to say whether the UKMO or GFS is correct.

[kold weather]

From snowfest to rainfest, thats the difference between the GFS and UKMO. The GFS is a big upgrade compared to the 06hrs run, the UKMO a downgrade, in fact the UKMO at 96hrs looks very poor in comparison with snow prospects greatly reduced for the whole of the UK. I'd put FI at 72hrs and place the rest of the output in the bin!

The 12z UKMO gives a classic snow-rain event for even parts of Scotland, only maybe far western Scotland and western part sof Ireland would hang onto snow the whole way through according to the 12z UKMO...we really need the 12z GFS solution to be correct.

The ensembles will be most interesting, gotta hope the ECM also discards the UKMO solution.

LS, the 12z UKMO is so far north its even marginal for you guys, you'd want the low to be that bit further east, put the 12z UKMO low 50-70 miles further east and its a stunner for you guys, but as it is its marginal for at least the east of Scotland IMO.

Edited February 19, 2010 by kold weather

[conor123]

Beastly snow storm followed a few hours later by very mild air with torrential rain on the 12z for next Thursday/Friday.

[grab my graupel]

Can someone tell me where to find the models as soon as they come out.

There you go

http://www.netweather.tv/index.cgi?action=charts;type=home;sess=24d0a8ca02f85ebfcfd611661501abc4

[Higher Ground]

I've noticed that in the latest runs, GFS appears to have consistently higher pressure over Greenland than UKMO, even from T+6 hrs (when it's 1030mb+ on UKMO but 1040mb+ on GFS). Don't know if this is just some artifact, or whether there really is that much uncertainty about initial conditions. Though I think I've heard that the initial conditions fed into models are if anything the most critical factor in accuracy further down the line?

Edited February 19, 2010 by Higher Ground

[weather eater]

I think we are seeing just how much difference for us in the UK small changes make. It’s been a curious day here with light sleet showers but not feeling especially cold, indeed the sun has been quite warm quickly melting the rather patchy snow from last night, we really do need a colder air source to negate a quick thaw. The 12z brings in a very nasty looking storm for Brittany, Normandy and the channel on Wednesday, given the GFS ability to over deepen LP systems it will probably downgrade but certainly one to watch. A difficult situation to call for the further outlook but the overall trend is still for a gradual warm up from the SW, it might well be that the models are not truly reflecting signals which might change that for a colder outlook, but as yet the signs for that are patchy and really have little credence as yet.

[LomondSnowstorm]

The 12z UKMO gives a classic snow-rain event for even parts of Scotland, only maybe far western Scotland and western part sof Ireland would hang onto snow the whole way through according to the 12z UKMO...we really need the 12z GFS solution to be correct.

The ensembles will be most interesting, gotta hope the ECM also discards the UKMO solution.

LS, the 12z UKMO is so far north its even marginal for you guys, you'd want the low to be that bit further east, put the 12z UKMO low 50-70 miles further east and its a stunner for you guys, but as it is its marginal for at least the east of Scotland IMO.

Yes, a middle ground between the GFS and UKMO would really be best now that I have looked at the uppers on the UKMO http://www.meteociel.fr/ukmo/run/UW72-7.GIF?19-17

[cooling climate]

This ozone chart screams potential blocking for the Iceland, Scandinavia area

in the not to distant future.

Edited February 19, 2010 by cooling climate

[Deep Snow please]

GFS snow risk 48-54 is looking like a nice storm, just waiting for Sunday then.

[kold weather]

12z GFS ensembles mostly agree with the UKMO solution rather then the GFS op run, though there are some that are in the middle ground that for sure.

A couple of horror shows on there as well tohugh it has to be said, the control run for example has a deep LP west of Scotland with rain for *everyone* bar maybe very high ground in the north.

Shows that we must get the low either over the UK or to the east, I'd say though 70% of the ensembles agree wit hthe 12z UKMO evolution, though with that evolution most would still see some transient snowfall.

[LomondSnowstorm]

12z GFS ensembles mostly agree with the UKMO solution rather then the GFS op run, though there are some that are in the middle ground that for sure.

A couple of horror shows on there as well tohugh it has to be said, the control run for example has a deep LP west of Scotland with rain for *everyone* bar maybe very high ground in the north.

Shows that we must get the low either over the UK or to the east, I'd say though 70% of the ensembles agree wit hthe 12z UKMO evolution, though with that evolution most would still see some transient snowfall.

Ok, not terrible news here but still pretty bad though horrendous for those further south. Still, the ensembles are just as volatile as the operationals.

LS

[Duane S.]

I'll take GFS's take on the middle of next week please. A snowfest for parts of the south for sure if that came off. Shame we have anything but model agreement on such an event. Although I still think this track is more likely than the UKMO which is still insistent on sending the lows a NE'erly track up through the UK which wouldn't be a lot of cop for the vast majority of us unfortunately.

[Iceberg]

The problem though Kold, is that the GFS ENS control run doesn't even have two centres at 48hrs, whereas the ops does.

With the vital difference at even this time frame I put alot more weight on the high res of the ops over the GEFS any time. The ECM will be interesting as it has even higher res at this range.

Interestingly the even, even high res NAE follows the GFS OPS over the UKMET or control for happens in the atlantic at T48.

[Guest FireStorm]

Why does the NAE miss alot of times on the 12z?