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Model Output Discussion - 30th November onwards

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ECM going for the flatter pattern like UKMO this morning.

 

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Obviously poor compared to recent runs but at least it looks like the jet diving South to our West on that 144 chart which will help.

Morning how can you tell what the jet is doing on that chart. Learning all the time :)

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Morning how can you tell what the jet is doing on that chart. Learning all the time Posted Image

 

Morning, hard to show you without being able to mark but I will try. It is about the shape of the trough disruption to  our West.

 

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If you look above that shortwave 1005mb you can see that the dsiruption in the trough above it is pointing SW  with a shortwave runner about to track South, when that happens it helps "tilt" our high more on a NE axis. the reason it is better to have a more amplified patter before this happens is that it gives us a better chance of getting energy underneath - other than it is obviously better to have the ridge at a higher latitude.

Sorry for the simplistic terms but hope that helps.

 

PS.

 

That is one reason I didn't write the UKMO off on second view despite it also looking poor

 

ECM 192 very messy.

 

Posted Image

Edited by Mucka

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Morning, hard to show you without being able to mark but I will try. It is about the shape of the trough disruption to our West.

Posted Image

If you look above that shortwave 1005mb you can see that the dsiruption in the trough above it is pointing SW with a shortwave runner about to track South, when that happens it helps "tilt" our high more on a NE axis. the reason it is better to have a more amplified patter before this happens is that it gives us a better chance of getting energy underneath - other than it is obviously better to have the ridge at a higher latitude.

Sorry for the simplistic terms but hope that helps.

PS.

That is one reason I didn't write the UKMO off on second view despite it also looking poor

ECM 192 very messy.

Posted Image

Thank you for taking the time to reply, yep I got what you were saying cheers :) Edited by TSNWK

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If ever a modelled chart screamed conflicting signals this would be it.

 

Posted Image

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Still looking very nasty for Thursday, becoming extremely windy for a time during the morning. Having a look round XC weather wind plots for Thursday using 00z data which is highlighting the potential for gusts of 75-80mph+ over N Britain, a bigger impact to the infrastructure likely due to wind than anything wintry, for the majority anyway!

 

post-9615-0-54574900-1386053538_thumb.gi  post-9615-0-93433000-1386053713_thumb.gi isotach km/h mean speeds.

 

 

Click to Thursday morning - 

 

 

http://www.xcweather.co.uk/GB/forecast

Edited by Liam J

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There is a lack of consistency in output at the moment but more than enough interest from various different models. There is enough to suggest that HLB could happen. Where it lands and what the effects are for us on our small island is guess work at this time. Better to have the potential, than to see the PV in situ with a flat pattern going on and on.

I know people will run through the 850's and see uppers that don't look great but look at the general pattern not specifics. Small change big differences!

Edited by That ECM

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An interesting post from Matthugo over on the Stratty thread... http://forum.netweather.tv/topic/78161-stratosphere-temperature-watch-20132014/page-22#entry2852445   ECM32 is showing blocking over Scandinavia this morning from mid Month.

 

I'm still waiting for the Greenland blocking it showed for over a month about this time last year...

 

A anti-cyclonic outlook this morning and although we see energy taken South into the Azores by the NWP, going forward this is not a set-up that will lend itself to high enough latitude blocking to bring a 'proper' easterly to the UK. The cold uppers will remain for E and SE Europe until there is another pattern change.

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I think you mean GEM, GME only goes to 72h. GEM looks better at 144 because it has better NE tilt and the pattern is further West - that said it is already losing the plot IMO by then so I didn't really care what it came up with after that.

 

Just a week after our failed Northerly, an Easterly? (GFS control thinks so)

 

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Good old GEFS ens 20  comes up with the goods, scandi High retrogresses to greenland with the help of a deep low prior to this dragging it that way from the SW, not many places for that to sink to, Know its unlikely, but if upstream patterns were a against it, would any ensemble show a route a to cold?

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Edited by tempestas

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Oh i'm loving the Gfs 0z trend this morning...could there be a beast coming from the eastPosted Image Posted Image

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Edited by Frosty.

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GFS and ECM remain fairly consistent with regard to the brief cold snap away from the far SW, but UKMO have significantly downgraded the cold, wintry potential this morning, with even the -5c Hpa line failing to reach parts of Wales and S England by 00 Fri. 

 

To my mind this event is looking less wintry with almost each run, but what can't be denied if a signficant wind event does look set to affect the northern half of the country for a time, wiith damaging gusts of 70mph+ on exposed hills and coasts in particular.

 

After the brief cold snap there is good support for a return to milder conditions, but any mild weather will probably be confined to northern and western areas, with high pressure also keeping many places dry.  Whether we then see HP develop over Scandi and Atlantic LP's starting to slip under the block towards mid month rermains to be seen, we all know the problems surrounding projected E'erlies beyond T+144hrs, but given the overall pattern it looks just as likely as a return to zonality. 

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GFS and ECM remain fairly consistent with regard to the brief cold snap away from the far SW, but UKMO have significantly downgraded the cold, wintry potential this morning, with even the -5c Hpa line failing to reach parts of Wales and S England by 00 Fri. 

 

To my mind this event is looking less wintry with almost each run, but what can't be denied if a signficant wind event does look set to affect the northern half of the country for a time, wiith damaging gusts of 70mph+ on exposed hills and coasts in particular.

 

After the brief cold snap there is good support for a return to milder conditions, but any mild weather will probably be confined to northern and western areas, with high pressure also keeping many places dry.  Whether we then see HP develop over Scandi and Atlantic LP's starting to slip under the block towards mid month rermains to be seen, we all know the problems surrounding projected E'erlies beyond T+144hrs, but given the overall pattern it looks just as likely as a return to zonality. 

 

Yep the ens agree with the last paragraph Shed, most show High setting up to our east in some sort, this can be the bringer of lasting cold to our shores or our worst enemy by halting the atlantic right over the top of us without the cold air reaching, cant say all to play for as it isnt. But certainly a few outcomes are viable which is better than just one....mild zonality.

Edited by Arron B

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Yep the ens agree with the last paragraph Shed, most show High setting up to our east in some sort, this can be the bringer of lasting cold to our shores or our worst enemy by halting the atlantic right over the top of us without the cold air reaching, cant say all to play for as it isnt. But certainly a few outcomes are viable which is better than just one....mild zonality.

Agreed Arron, the worst synoptics of all imo (even worse than a raging Cuban Blowtorch) is a fat Scandi high that keeps most of Europe bitterly cold, but does not extend it's influence across the UK, with the western N Sea becoming it's frontal graveyard. We've seen this kind of 'close but not close enough' pattern several times across recent Winters, so as you suggest Scandi highs are guaranteed good news for most of N Europe....but not the UK and most definately not Ireland. 

Edited by shedhead

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Agreed Arron, the worst synoptics of all imo (even worse than a raging Cuban Blowtorch) is a fat Scandi high that keeps most of Europe bitterly cold, but does not extend it's influence across the UK, with the western N Sea becoming it's frontal graveyard. We've seen this kind of 'close but not close enough' pattern several times across recent Winters, so as you suggest Scandi highs are guaranteed good news for most of N Europe....but not the UK and most definately not Ireland. 

 

Yes for the UK to benefit you have to height extension towards Greenland at a high enough latitude. Nothing really suggests that is going to happen. Still, on the positive side this sort of battle doesn't usually start this early and given a few notable extensions, conventional zonality is the general norm at this time of year.

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Good morning everyone. Here is how I see the outputs of GFS, UKMO, GEM, NAVGEM and ECM taken from their midnight outputs today Tuesday December 3rd 2013.

 

All models show High pressure moving gently South over Southern Britain today as a weak cold front sinks South over Britain with some rain in places as it comes. Behind it some clearer skies develop for a while with a patchy frost tonight before another front sweeps SE across the UK on Thursday bringing a strong to severe gale NW wind to the NE for a time. Some wintry showers of sleet and snow will affect these areas too for a time before the drier weather over Southern and Western areas at the end of the week spreas to these regions too. Over the weekend cold and frosty weather is shown to be slowly replaced by cloudy and milder conditions as High pressure is shown to slip SE across Southern Britain and on into NW Europe backing winds to a milder SW direction.

 

GFS then shows next week as being much milder for a time with Southerly winds wafting North over the UK around High pressure over SE Europe. In any brighter intervals it could become very mild in places. Later on though the High moves North to Scandinavia and a puddle of very chilly air is sent NW from Europe towards the UK. At the same time Low pressure off the Atlantic engages this cold air to deliver a spell of unsettled and wet weather for many and it may be cold enough for some of this rain to fall as snow for a time before the end of the run sees much more unsettled weather with rain or showers at times around deep Low pressure over the Atlantic.

 

UKMO shows High pressure covering much of SW Europe early next week with mild Atlantic air drifting over the UK from the West or SW. The mildest weather will be towards the North and West where the cloud will be thickest and the winds more strong while Southern and Eastern areas remain more at risk of cloud breaks at times perhaps with some mist and fog patches and somewhat lower surface temperatures as a result in very light winds.

 

GEM today shows a pattern we'd crave for in July as it would mean very hot weather as Southerly winds move up across the UK all the way from North Africa as High pressure settles down over SE Europe. As it is in any brighter breaks in the SE it could become exceptionally mild for early December with all areas sharing in very mild conditions at least with little in the way of rain away from the far West.

 

NAVGEM shows High pressure collapsing all the way down to the Med early next week with pressure falling to the NW setting up a mild and strong SW flow over Britain with troughs crossing NE with rain at times for all in temperatures close to or somewhat above average.

 

ECM takes High pressure only briefly away to the SE early next week before bringing it back NW in increasingly warm uppers to settle over the UK with a ridge to Scandinavia by Day 10. It looks like cloud will again be a big factor in determining conditions at the surface and it may well be that cloudy skies may keep cool conditions at the surface. However, if clouds break some very mild conditions could develop locally for a time though with patchy frost at night before more generally colder conditions begin to spread from the SE across Southern Britain at the end of the run as the UK High ridges towards Scandinavia.

 

The GFS Ensembles show our brief cold snap as a blink and miss it affair before we revert back to probable anticyclonic gloom as cloudy skies around High pressure to the SE looks likely for much of next week with very little rainfall for the South and East until later as things become more mobile as Low pressure edges in towards Western Britain at times with rain for all on occasion.

 

The Jet Stream today shows the flow to the North tilting SE down the North Sea in a day or two before resetting NE towards NW Scotland and on over Scandinavia next week keeping the UK very much on the mild side of the flow for the time being.

 

In Summary today if we were in Summer we would be staring down the barrel of some very high temperatures as High pressure looks like slipping down to SE Europe and sending long fetch Southerly winds from North Africa, Spain and France across the UK. Being as it's winter things are much less clear cut as cloud cover will likely set up an inversion with cloudy skies and temperatures nearer to average but largely dry, frost and fog free. However, if clouds break occur it is not out of the question for some very mild conditions to develop for a time next week with 15C or more not entirely out of the equation if the sun breaks through. Later on though there is still suggestion that High pressure rises over Scandinavia and this would gradually pull colder air from Eastern Europe towards the UK in 10-14 days time but this is an ocean of time away at the moment and must remain speculative so the UK Winter remains on hold for the time being.

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The Gfs 00z op run is still showing a potent Arctic blast by thursday night and especially through friday, max temps struggling to get above freezing for many..so the first ice day of the winter, add in the windchill, feeling bitter and with snow showers spreading south, it's a fantastic but short taste of winter, a lot of snow across the far north on thursday and friday and more cold weather on the way.

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Edited by Frosty.

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Exciting update there from Ian!  Sounds like a step change from the Met office is on its way! Hopefully the lunchtime update of the long range forecast update will reflect this !

I have been watching the GFS ensembles over the last few days and what started with 1 or 2 easterlies showing there have gradually been more and more so we are now at nearly 50% showing some sort of scandi High. Hopefully this trend will continue. We still need to see some ridging up towards Greenland though otherwise we just watch and drool as Europe gets covered and we are on the periphery

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Details on just where the upper ridge settles to the E/NE of the UK have yet to be settled. However all 3, not consistently, anomaly models show a similar idea. That is +ve height anomalies building NE of the UK with a marked upper trough about 30 or so west. Just what the bottom 18000ft will show beneath that is a good question. But the indications are looking at the wavelengths developing on all 3 charts around the northern hemisphere suggest a very slow moving upper air pattern is evolving. So lots of interest for folk watching the synoptic models as they try to fit the anomalies at 500mb. How cold after about 5-7 days is the question. It seems very unlikely that mild will feature in any forecast other than briefly now and then to me.

Think that very much depends on location to be fair John.  Hard to see much in the way of persistent mild weather for your neck of the woods and indeed much of central/eastern England, but the west and much of Scotland could get some mild, even very mild spells of several days duration. Would not be at all surprised to see the normal Foehn suspects topping out at 13-15c next week.

Edited by shedhead

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