12z Model discussion - rain, sleet or snow?

[Cloud 10]

Check out the nogaps,almost a carbon copy of the GEM!

[skywatcher]

Yes and particularly when you have been watching it develop all week, and then it

only delivers for a handful of members.

Looks like Saturday is heading for a none event if the MetO gets it's way aswell.

Indeed. Yes, it might come off and I hope it does. But recent history doesn't make me hopeful. Doesn't stop me avidly going through each new set of model output though {) I just never move fast enough to make intelligent comments. Seriously, though, all eyes south for Thurs but all eyes in the NE looking towards Sat for our best chances.

[smhouston]

ohh,excellent ensembbles in my eyes! more members going for a more prolonged period of coldness

[Optimus Prime]

NOGAPS and GEM are excellent tonight;

NOGAPS;

GEM;

Both suggesting a good solid easterly flow to develop. They are the two most unreliable but seeing as there are two models suggesting this I wouldn't rule it out. The JMA doesn't work so can't say anything about that.

I actually think the easterly scenario is quite possible but would go with the atlantic rolling back in with cool zonality for a while.

[Turnedoutniceagain]

NOGAPS and GEM are excellent tonight;

Both suggesting a good solid easterly flow to develop. They are the two most unreliable but seeing as there are two models suggesting this I wouldn't rule it out. The JMA doesn't work so can't say anything about that.

I actually think the easterly scenario is quite possible but would go with the atlantic rolling back in with cool zonality for a while.

A splendid sight.

Not much action on the "Aaahhh Spring has sprung" thread for a day or 2 :lol:

Just keep everything crossed !

Edited February 6, 2007 by Nick F
Downsize quote to save space

[PersianPaladin]

Check out the nogaps,almost a carbon copy of the GEM!

Please don't post pornography in this forum.

:lol:

[Iceberg]

A quicky to explain the possible meto's thinking.

1000-850 thicknesses are forecast to be 1300 from the M4 northwards even at noon on Thursday on the lastest raw meto output.

Automatically generated snow charts will be extremely unreliable in this set up,as steve indicated.

Due to the 3 hr initialisation periods, modes like GFS will NOT take the cooling effect of a good snow cover into account, particularly with 1000-850 thicknesses and DP's hence the Meto's forecast for the band to be snow for most of the country away from the coasts.

I still think that away from the south coast the likes of the cotswolds could see 8 inches.

[Yeti]

The BIGGAPS really is a complete joke - if it is forecasting an E'ly, expect a W'ly!

Seriously though, I do think Saturday holds better prospects for the N, it will be great if the 18z shows this, too. Not much support from the ECM though :lol:

Certainly not over for the N for Thursday, but looking ever less likely! I would pay good money to see that low 150 miles further N.

[Turnedoutniceagain]

Check out the nogaps,almost a carbon copy of the GEM! :lol:

Not much debate on this FI chart at the moment. Good Scandi highs here (for FI of course).

Forecasting seems to have stalled at Thursday, it's almost as though we daren't look any further as it's bound to end in tears & bitter recrimination !!

[Cloud 10]

Please don't post pornography in this forum.

:lol:

I suppose i could have posted an ecm chart,but that wouldn't be in my nature

"I think therefore i ramp" this should be your new motto P.P.

[wellington boot]

Snow to 540 DAM in easterly set ups...

S

Both suggesting a good solid easterly flow to develop. They are the two most unreliable but seeing as there are two models suggesting this I wouldn't rule it out. The JMA doesn't work so can't say anything about that.

I actually think the easterly scenario is quite possible but would go with the atlantic rolling back in with cool zonality for a while.

This is not to say those charts are reliable or anything, but i really cannot believe how identical they are. It's really incredible. I thought they were th same chart for a moment.

Edited February 6, 2007 by CatchMyDrift
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[The PIT]

The ECM doesn't thrill me very much. I'd put it in the recycling bin.

[Long haul to mild]

Just for the sake of completeness, here's the JMA for Saturday; somewhere between the GFS and ECM by the looks of it.

Certainly doesn't back up the GEM and NOGAPS, so that's the outside bet at the moment.

JMA

Edited February 6, 2007 by Chalk Serpent

[mcweather]

Hi guys I think even at this relatively late stage there is still great uncertainty, ( The Meto forecasters keep on mentioning this) Thursdays best guess scenario may yet prove to be over cooked. I still think that the northward progress is being pushed too far. If the low tracks even the slightest bit further south than progged then it may well be southern England that takes the fullbrunt. Still a great deal to play for in this intriguing set up yet

[wellington boot]

While I would like Thursdays event to be further north from a selfish point of view, I am willing to take one for the team and will the LP further south!

This show of selflessness comes from my belief that if it is more southerly then Saturdays event will be better for the country and will pave the way for a longer spell of cold. If the track is further North on Thursday I fear it may result in the mild weather making more of an impact into next week!

AM

Much appreciated anti mild. It's settled then, the low is going to track south because anti mild is taking one for the team...

With regards tonight's models, I would back what many have already said, in taking charts beyond 72-96 hours with a pinch of salt. There is so much disagreement before 96, let alone afterwards, that it really isn't even helpful to go by reputation (ie back the ecm). Because you'd expect all the models to be roughly right out to 96 in a normal setup, but they're so different that some, including the big ones, will be proven wrong, so anythign they forecast afterwards is rendered irrelevant.

[The PIT]

Much appreciated anti mild. It's settled then, the low is going to track south because anti mild is taking one for the team...

With regards tonight's models, I would back what many have already said, in taking charts beyond 72-96 hours with a pinch of salt. There is so much disagreement before 96, let alone afterwards, that it really isn't even helpful to go by reputation (ie back the ecm). Because you'd expect all the models to be roughly right out to 96 in a normal setup, but they're so different that some, including the big ones, will be proven wrong, so anythign they forecast afterwards is rendered irrelevant.

Yes the inquests into this could be interesting. I'd luv to be fly on the programmers wall.

[Nick F]

yes look at these 1963 charts. looks like 540ish DAM here, but given that it's 1963 and the 850s are so low, ill bet that setup snowed:

http://www.wetterzentrale.de/archive/ra/19...00119630107.gif

http://www.wetterzentrale.de/archive/ra/19...00219630107.gif

This is not to say those charts are reliable or anything, but i really cannot believe how identical they are. It's really incredible. I thought they were th same chart for a moment.

Hi Wellington, the colours on those charts are the geopotential height in decameters (gpdm) of the 500mb pressure surface and not 540 DAM as in the 500-100mb thicknesses which have 510, 528, 546, 564 lines etc shown on the thickness chart below:

http://www.wetterzentrale.de/pics/Rtavn063.png

Bit confusing, but the colours are heights at 500mb and the DAM lines which you are thinking of in terms of 528, 510 DAM line etc are thicknesses of the air between 500mb and 1000mb, you also get thickness values between 850 and 1000mb which are better indicator of snow (below 1290 gpdm is best). Aswell as the heights for 500mb shown on the WZ charts by the colours you can also get 850mb height charts and also for other standard levels aswell.

[MKN]

Does anyone have any satalite pictures of whats been going on to the system approaching us for thursday?

[skywatcher]

Surely much depends on the accuracy of the models to date re Thurs. If there's a reasonable degree of accuracy here we can start looking at the Sat charts and pick the one which is most likely to be accurate. But if it does track further south than many are suggesting, then all bets are off. In my ignorant and uninformed opinion, of course.

[wellington boot]

Just for the sake of completeness, here's the JMA for Saturday; somewhere between the GFS and ECM by the looks of it.

Certainly doesn't back up the GEM and NOGAPS, so that's the outside bet at the moment.

JMA

With all impartiality, i would suggest that the JMA looks decidedly dodgy right now. From the word go, it looks like it's taking all the atlantic low pressure too far north, all the way through in fact. Like it's underdoing the high pressure to the north and east. On the other hand, it actually did ok with the setup we are seeing now/soon to see, or better than certain other big names, such as the ecm, by suggesting that the high would stand firm and deflect the lows south, something which the other models really didnt get at all. So maybe it has a better handle on the high pressure. I doubt it though.

Edited February 6, 2007 by wellington boot

[Matty J]

Well there's my opinion. Have fun.

Interesting opinion.

But, are you saying that East Anglia and the S/E will receive no snow? The highest risk of the worst snowfall appears to be in a line between Birmingham and Norwich, maybe even this will be a little further south in the end but who knows!

On a different note, the ECM for saturday isn't over exciting for my part of the world to say the least! Still plenty of time for improvement tho!

Matt

[The PIT]

Interesting opinion.

But, are you saying that East Anglia and the S/E will receive no snow? The highest risk of the worst snowfall appears to be in a line between Birmingham and Norwich, maybe even this will be a little further south in the end but who knows!

On a different note, the ECM for saturday isn't over exciting for my part of the world to say the least! Still plenty of time for improvement tho!

Matt

Well since the essemblies are all over the place in three days time I'm not really surprised. It's like the old days this is.

[cartedj]

Does anyone have any satalite pictures of whats been going on to the system approaching us for thursday?

http://wind.met.fu-berlin.de/cgi-bin/meteo...playmode=Endlos

Try this Snow Tornado

Edited February 6, 2007 by cartedj

[wellington boot]

Hi Wellington, the colours on those charts are the geopotential height in decameters (gpdm) of the 500mb pressure surface and not 540 DAM as in the 500-100mb thicknesses which have 510, 528, 546, 564 lines etc shown on the thickness chart below:

http://www.wetterzentrale.de/pics/Rtavn063.png

Bit confusing, but the colours are heights at 500mb and the DAM lines which you are thinking of in terms of 528, 510 DAM line etc are thicknesses of the air between 500mb and 1000mb, you also get thickness values between 850 and 1000mb which are better indicator of snow (below 1290 gpdm is best). Aswell as the heights for 500mb shown on the WZ charts by the colours you can also get 850mb height charts and also for other standard levels aswell.

Oh dear im ashamed . What a lapse. I thought they corresponded somehow, the colours and the DAM readings. Because if you actually use the colour coding, the number match up surprisingly accurately.

http://www.wetterzentrale.de/pics/Rtavn061.png

http://www.wetterzentrale.de/pics/Rtavn063.png

The '528' lines on both charts are almost in identical positions!

Anyway, thanks, thats an embarassing hole patched up.

[bennytes]

Does anyone have any satalite pictures of whats been going on to the system approaching us for thursday?

http://oiswww.eumetsat.org/SDDI/cgi/listIm...201000#controls