Winter Model Discussion 12Z 22/1/13 onwards.

[Jason M]

It will be very interesting to see the control run and ensembles tonight.

That sneaky bit of trough disruption at weekend could really throw a spanner in the works if it sharpens a little more.

Jason

[bradymk]

Not really.The vortex will continue to be disrupted well into February IMO and so any block to our east will have the potential to anchor further north and, if the Canadian vortex takes a hit, will have the potential to ridge to Greenland. One thing I've noted on today's runs is that the vortex intensity recently advertised, may have been overdone......which really doesn't come as a surprise to me as the models begin to latch on to downwelling from the strat.

Thanks CC, wasn't too sure with my point so thanks for clearing that up. GEFS 12z suite definately started to hint at some sort of mid atlantic ridge day and GFS 18z op would show some great charts if it ran a bit further, at 300+ I know but it has support. Edited January 22, 2013 by bradythemole

[Rocheydub]

Good lord! The straw clutching thread achieves new heights!

There shall be a powerful low pressure system influencing our weather by sat/sun bringing warmer air and high winds and rain. The models show this and there's no disputing it, please accept this, and move onto the next cold spell, whenever that may be!

Glad most of you had a great cold spell, personally, it was a non event for me. A few frosty nights and a sleety day or 2.... I'll not be sorry to see this very weak scandi go away! Time for a proper greenie HP.

[weather_it_will]

Plenty of blocking to the north and west at end of the run. Lots of potential.

Edited January 22, 2013 by snow is falling

[Rocheydub]

Plenty of blocking to the north and west at end of the run. Lots of potential.

Not a proper high though, only a surface high. Mid atlantic ridge, not a great return IMO.

[-uksnow-]

Not a proper high though, only a surface high. Mid atlantic ridge, not a great return IMO.

Yes but most crucially look at that lovely bit of PV over Scandi aiming itself to drop down on us with the MAH ridging into greenland, obviously this is at 384 so no point in taking it literally but a fair few ensembles and a couple of op runs have toyed with this idea in the last few days/

[Djdazzle]

Good lord! The straw clutching thread achieves new heights!

There shall be a powerful low pressure system influencing our weather by sat/sun bringing warmer air and high winds and rain. The models show this and there's no disputing it, please accept this, and move onto the next cold spell, whenever that may be!

Glad most of you had a great cold spell, personally, it was a non event for me. A few frosty nights and a sleety day or 2.... I'll not be sorry to see this very weak scandi go away! Time for a proper greenie HP.

What you say is likely, but not certain. It is not a done deal until it happens. There have been a few subtle shifts today, which could have major effects further down the line.

[damianslaw]

Having read the thoughts of some on the strat thread, what we should expect to see as we move through next week is the atlantic longwave trough making it across to scandi with some ease which suggests quite a zonal spell, but this is needed if we are to see heights building to our NW in time. For those looking/expecting height rises to the NW as we move into February - the suggestion of stronger heights to the NE won't enable such developments to occur quickly.

Its very plausible that we may well enter a shortlived spell of atlantic weather on a west-east trajectory - a flat pattern, but the ejection of energy off the weakening canadian PV will quickly burn itself out - no way can it sustain the energy it is due to exert this weekend for any length of time - its been waiting to releasing its energy but it wil be in one quick sharp burst, once its done this, it will have nothing left enabling mid atlantic heights to build and move north into Greenland - with all its energy being transferred into the siberian PV. I don't think the models will get a good grip on this evolution until quite short notice, the progged low heights associated with this energy is very positive in this respect, I'd much more concerned if the energy was much weaker - it suggests the energy is wanting to quickly move into the siberian PV as quickly as it can thanks to the effects of significant warming from above.

[Jason M]

Good lord! The straw clutching thread achieves new heights!

There shall be a powerful low pressure system influencing our weather by sat/sun bringing warmer air and high winds and rain. The models show this and there's no disputing it, please accept this, and move onto the next cold spell, whenever that may be!

Glad most of you had a great cold spell, personally, it was a non event for me. A few frosty nights and a sleety day or 2.... I'll not be sorry to see this very weak scandi go away! Time for a proper greenie HP.

In your part of the world, no argument with this whatsoever.

Jason

[Djdazzle]

Having read the thoughts of some on the strat thread, what we should expect to see as we move through next week is the atlantic longwave trough making it across to scandi with some ease which suggests quite a zonal spell, but this is needed if we are to see heights building to our NW in time. For those looking/expecting height rises to the NW as we move into February - the suggestion of stronger heights to the NE won't enable such developments to occur quickly.

Its very plausible that we may well enter a shortlived spell of atlantic weather on a west-east trajectory - a flat pattern, but the ejection of energy off the weakening canadian PV will quickly burn itself out - no way can it sustain the energy it is due to exert this weekend for any length of time - its been waiting to releasing its energy but it wil be in one quick sharp burst, once its done this, it will have nothing left enabling mid atlantic heights to build and move north into Greenland - with all its energy being transferred into the siberian PV. I don't think the models will get a good grip on this evolution until quite short notice, the progged low heights associated with this energy is very positive in this respect, I'd much more concerned if the energy was much weaker - it suggests the energy is wanting to quickly move into the siberian PV as quickly as it can thanks to the effects of significant warming from above.

Very interesting. So I take it that you would prefer the Atlantic to smash through this weekend as opposed to the block fighting? Short term pain for long term gain!

[pipsta]

Best post all day Damian, well thought out and very plausible projection of events! Given the size of that low coming out of Greenland what a way to empty the PV's tank over that side of the globe. A very plausible route indeed.

[Matty M]

All 18z show an incredibly deep Atlantic depression but one or two take it to new levels.......

Sub 915mb

Also live risk of a severe wind event just prior to this for parts late Friday into Saturday.

[lord stratus]

Good lord! The straw clutching thread achieves new heights!

There shall be a powerful low pressure system influencing our weather by sat/sun bringing warmer air and high winds and rain. The models show this and there's no disputing it, please accept this, and move onto the next cold spell, whenever that may be!

Glad most of you had a great cold spell, personally, it was a non event for me. A few frosty nights and a sleety day or 2.... I'll not be sorry to see this very weak scandi go away! Time for a proper greenie HP.

This cold spell has proved once and for all that you dont need a Greenland HP to guarantee a wintry outbreak. I've seen shorter cold spells and with less snow with a GH in place!

[be cause]

I for one will be glad to see a mobile westerly .. a lot of snow here in my childhood came from the west .. and the last few days have left my world green [ with envy .. lol ]

[shotski]

The 00z GFS continues the trend of sending the weakening second lobe of the PV to siberia and

the void if filled by an impressive looking Atlantic Ridge. Anyone who can't see promise in this

needs to go back to their regionals and report on snow depth

[Snowmad79]

I know this will come to nothing but look at the adjustments on the Output in the so called reliable. The top yesterdays 96hr and today 72hr. I'm probably looking at small detail a little too much in hope but compared with yesterday we now have a developed 990 low rather just a shallow short wave and where as HP bridged across france at 72hr, today LP is digging in more SE/

Slap me and tell me that there is absolutely no chance of LP going SE into France or the med at this stage is there ??

[MattH]

I think these are what you are after Matt?

MJO.html

Spot on, thank you.

Matt.

[Katiewombat]

I know this will come to nothing but look at the adjustments on the Output in the so called reliable. The top yesterdays 96hr and today 72hr. I'm probably looking at small detail a little too much in hope but compared with yesterday we now have a developed 990 low rather just a shallow short wave and where as HP bridged across france at 72hr, today LP is digging in more SE/

Slap me and tell me that there is absolutely no chance of LP going SE into France or the med at this stage is there ??

I can't read the models but after reading this thread for 4 winter's and in particular this winter

A non biast point of view, based on just reading posts I would say there is probably around 40 percent chance.

Katie

[Gibby]

Good morning. Here is the latest report on the 00z output from the 00z outputs of GFS, UKMO, GEM and ECM for today Wednesday January 23rd 2013.

All models show universal agreement on a change in the weather in 48 hours or so time. The current cold and snowy spell still affecting parts of the South will die out through the day as the offending Low pressure in the channel fills up. A weak ridge of High pressure will gradually ridge down from the North in association with High pressure slipping South to the East tomorrow. The wintry showers near Eastern coasts will also die out as the High pressure builds but could be replaced inland by freezing fog tomorrow. On Friday pressure will be falling in the West as Low pressure moves steadily in from the West bringing a spell of rain East over the UK on Friday. The rain may be preceded by a spell of snow briefly. As the rain clears temperatures will rise strongly as winds settle SW. Later in the weekend an intense depression out in the Atlantic sends a squally cold front over the UK with a spell of heavy rain followed by squally showers and sunny intervals in a chilly SW wind. Thereafter, all models show an increasingly mild SW flow with rain at times gradually becoming more confined to more Northern and Western regions of the UK later as the South sees pressure build from the South. The above general trend is shared by all models with very little sign of a return to cold from this morning's output.

The GFS Ensembles show a warm up at the weekend with a gradual cooling off to normal values through the end of next week and beyond. Naturally there is a lot of spread between the members but there is little evidence of cross member support showing for a quick return to cold. Plenty of rainfall is expected at times too increasing the flooding risk following the snow melt.

The Jet stream shows the flow crossing the Atlantic on quite Southerly latitudes at the moment. It looks likely it will move slowly North to be around the UK latitude in a week or so time.

In Summary a quick thaw is on the way. Once arrived the emphasis will shift over the weekend and start of next week to flooding especially in the East and SW of England and Wales where a quick snow melt will be accompanied by heavy rain. Longer term amounts of rain will reduce as pressure builds from the South or SE with temperatures into double figures in places by day later next week in the South and East. The North won't be quite as mild though with further rain at times.

[Cecil Hogmanay Melchett]

The poor profile around Greenland continues.

Im still hoping the recent SSW will have an impact on those blues and purples that have dominated to our North west since winter began!

In the meantime the block that has forcaed the atlantic SE is getting pushed east and the jet is heading more or less straight for us,we desperately need some sort of HLB to deflect things south again.

[UV-RAY]

Well another cracking set of model runs this morning, low heights to our North and big fat high over the Azores. No sign of the elusive Greenland high and once this pattern is locked in, I can't see an easy return to colder conditions anytime soon.

[jules216]

quite a few ensebles gfs0z are showing greeny high in FI so hopefully this trend will continue, probably for coldies we should perhaps take a few days break from model watching as the atlantic lows could be hard to shift eventualy and it could be tough way to get the greeny in place we dont want for high to end up right over us

[Bristawl Si]

Well another cracking set of model runs this morning, low heights to our North and big fat high over the Azores. No sign of the elusive Greenland high and once this pattern is locked in, I can't see an easy return to colder conditions anytime soon.

What's happened to the effects of the Strat Warming - thought it was meant to be at its most potent v soon? Just wondering.

Greenie high seems to be rather elusive

[UV-RAY]

What's happened to the effects of the Strat Warming - thought it was meant to be at its most potent v soon? Just wondering.

Greenie high seems to be rather elusive

I remain unconvinced of it's overall impact BB, the theory will be tested over the coming month.

[IDO]

Very poor GFS for the height of Winter. Nothing cold for the UK right out to T384. Then it is a HP close to the west of the UK that may (or may not) ridge to Greenland. ECM has nothing cold on its ten day charts. If we are going to get a return to cold it is probably going to be mid Feb now.

A typical cool zonal pattern for the north from the weekend but further south may have more influence from ridging from the Azores High, so milder at times.

Wrong time for the pattern to shift to cyclonic westerly's and it appears that the SSW has moved the goalposts for the UK and left us the wrong side of any favourable blocks. Will this also continue for the rest of the winter? A total destruction of the PV pieces may be needed for us to save Winter. Other background signals may be great (MJO & GWO) and in a normal winter we would be hopeful of some cold/snow, but with the SSW, who knows, this may counteract these signals, and we could end up cursing our luck.