Model Output Discussion 25/11/2012 12Z onwards

[cyclonic happiness]

Would anyone mind explaning to me what a short wave looks like on the charts. Is it the horn shaped thing that moves from west to east across the atlantic with higher uppers?

Here's an example of the troughs and shortwaves that everyone keeps on going on about, hope it helps a bit?

[Methuselah]

Looks like a hell of a lot of scatter in the ensembles to me, especially the further into Europe you go;

http://www.jp2webdes.../two/ensembles/

Plenty of cold continuity there, but looking at FI is fruitless currently with so many varying options.

There's almost always plenty of scatter in the ensembles, AWD...I think that that's how models work?

[AWD]

There's almost always plenty of scatter in the ensembles, AWD...I think that that's how models work?

True RP. Just highlighting the fact that there's a lot to sort out in the medium term without trying to find trends in the long term. If the medium term is wrong, then the long term will be wrong.

[Jayces]

Here's an example of the troughs and shortwaves that everyone keeps on going on about, hope it helps a bit?

That's really useful thanks.

I have followed Nick Sussex's posts every winter as he seems to be the shortwave king so knew what they were but why can they appear on a run and then dissapear on the next run or is that just a computer model thing?

[The Northern Ramper]

Nick Sussex the King of the Shortwaves - He will love that title.

[Jayces]

People ignore his input at their peril, yes there are some great knowledgeable posters here but I always remember one year where a raging easterly was forecast from a long way out and he warned about shortwaves and I think it was something like a day or two before it was going to hit and a shortwave appeared near finland heading south through the English channel and boom the easterly was swept away

[cyclonic happiness]

That's really useful thanks.

I have followed Nick Sussex's posts every winter as he seems to be the shortwave king so knew what they were but why can they appear on a run and then dissapear on the next run or is that just a computer model thing?

Shortwaves have a nasty habit of popping up at short notice (not the reason they're called 'short waves' btw) in the most annoying of places and they are responsible for wrecking many a good easterly at the last minute.

Some models like the GFS tend to go a bit shortwave mad when they're not quite on top with what's happening, so that's why you should NEVER trust a big glut of shortwaves that look like they're gonna spoil the plot in 'Fantasy Island (F.I.).

If you want to know where fantasy island starts, it's usually where the ensembles chart starts to scatter widely enough as most of the individual ensembles aren't to be trusted.

[Iceaxecrampon]

The tension rises: panic-buttons are being pressed; the wine, Scotch & vodka bottles are being opened; the cigarettes are burning away furiously and members' fingernails are being chewed in anticipation...Is the GFS going to making mazy runs towards Snowmageddon - or will they be blindsided by a one-off counter-attack by the Atlantic Short Waves?

Who knows...Game on!

Thanks for increasing the frenzy another notch.............

[A.J]

The tension rises: panic-buttons are being pressed; the wine, Scotch & vodka bottles are being opened; the cigarettes are burning away furiously and members' fingernails are being chewed in anticipation...

Who knows...Game on!

Yep, the time is fast approaching...and for us which colour will dominate this afternoon?...cold blues or blow torch reds?......What will be shown in this afternoon's F1?.....Yes, it's time for the Brazilian GP! ......

[Mr Frost]

I really do wish the GFS would only release 2 updates per day. It seems they just chuck out 4 a day for the hell of it!

Does anyone know why there are 4 per day?

[Methuselah]

Thanks for increasing the frenzy another notch.............

Hey, you're welcome!

[ITSY]

ha got to love GFS. at 78 = no shortwave off greenland. at 84 = shortwave central. Still, could be overcome - as it has been by other models.

EDIT: I've become one of these people who make statements way too prematurely. the shortwave is no where near as large or disruptive, by my eyes anyway, come +96.

Edited November 25, 2012 by ITSY

[snowking]

Well im going to do one of those annoying early updates

Marginally better 12z so far with blocking further W into Greenland as a result of some slightly better WAA when compared to the 6z

SK

[PubliusEnigma]

At T84 the main differences are so far, the trough is still there to our SE, although the colder north easterlies

have edged a little further ease across into the Netherlands. With The Azores High ridging over Ireland and

Scotland, so some cold and frosty nights to come here by later next week. The Canadian Low has continues

to be modelled moving east past Steve Murr's observation point at the South Of Greenland. What happens

in the next half dozen frames is important, will it slow and track back NW, will it send a short wave off SSE

past the SW of the UK, or will it continue to track slowly east, closing the link from the AzH to the Arctic High ?

[nick sussex]

Here comes the Canadian low, remember we need this to head up the west of Greenland.

The upstream pattern looks a bit more amplified here.

[Buriedundersnow]

I really do wish the GFS would only release 2 updates per day. It seems they just chuck out 4 a day for the hell of it!

Does anyone know why there are 4 per day?

i think it would be better with 2 runs a day aswell but maybe the gfs needs 4 runs a day u have to remember america get much worse weather than us and maybe need the 4 runs a day to keep ontop of possible hurricanes or tornadoes.

[SMU]

http://modeles.meteociel.fr/modeles/gfs/runs/2012112512/gfsnh-0-96.png?12

At 96 early doors all eyes towards that low heading towards Greenland- if it gets west everything will fall into place

S

[Continental Climate]

Lots of ugly little shortwaves everywhere http://www.wetterzentrale.de/pics/Rtavn1021.png!! They are like little gremlins and breed like flies

[bobbydog]

whilst waiting for the 12z to roll out, i looked back through the previous run. what i did notice is that the high pressure builds towards greenland then gets squeezed out by cold PM air. it then rebuilds, dragging colder air over us each time. this happens three times within one run and each time it seems to get progressively colder but never really warmer in between. if this pattern keeps repeating for an extended period, we should get repeated shots at cold snowy weather, with each one possibly colder than the last. or eventually the HP wins out and we get locked in a decent cold flow.

i have a feeling this could be a winter to remember, for all the right reasons......

[ITSY]

a degree or so colder for most come Wednesday. Max's at 3-6 for inland areas and night frosts of between -1 - -3. Could be a lot worse!!

[PubliusEnigma]

http://modeles.meteo...snh-0-96.png?12

At 96 early doors all eyes towards that low heading towards Greenland- if it gets west everything will fall into place

S

Its become stationary, but thrown a secondary low ESE towards Scotland, which is then somehow modelled to progress

east past Scoland and link up with the trough near Denmark. By T114 the new developing deep low is modelled further

NW on the 12z

Edited November 25, 2012 by PubliusEnigma

[ITSY]

http://modeles.meteo...snh-0-96.png?12

At 96 early doors all eyes towards that low heading towards Greenland- if it gets west everything will fall into place

S

Well, steve, you may be right. that Low is about 100miles further WNW so far...

[Continental Climate]

http://www.wetterzentrale.de/pics/Rtavn1141.png!! A better run coming up more ridging in the atlantic and the canadian low will head up west greenland ( I hope)

[Jonan92]

Lots of energy going north

[MR EXTREMES]

obessions with sortwaves creeping in again.

this run is heading in a perfect direction game on.