Model Output Discussion 17th Dec.2013-12z onwards.

[SMU]

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=534&mode=0&carte=1&run=10

 

Todays 06z CFS between 420 & 580 shows what old man met is commenting on above- where a quick rise in pressure nearly bauks the atlantic flow- but eventually gets swept away- so near & yest so far on that run....

 

 

anyway - if anyone was wondering what to look for

S

Edited December 18, 2013 by Steve Murr

[Gibby]

Good evening. Here is tonight's report on the midday outputs from NWP for today Wednesday December 18th 2013.

 

All models show an active cold front attached to a very deep depression to the NW of Britain crossing quickly East over the UK this evening. Following behind will be a colder and still windy period of weather with a mix of clear or sunny intervals and heavy and frequent showers of rain, hail, sleet and snow the latter most likely but not exclusively over the hills. Then after a bright start to Friday a new area of heavy rain will sweep NE across the UK with renewed severe gales in the NW. Showery air will return to the North of the UK later with a slower clearance for Southern areas as a new wave runs along the cold front giving rise to another very wet spell for the South on Saturday. Sunday will then be a colder day for all with sunshine and showers, wintry on hills.

 

GFS then shows the whole of the Christmas Week as wet, windy and occasionally stormy with severe gale or even storm force winds at times giving rise to flooding and wind damage issues almost anywhere over the period. After Christmas improvements are slow with plenty more fast changing conditions alternating between wet and windy weather to sunshine and showers, wintry at times. Overall things would turn somewhat colder, especially in the interludes between the rain areas.

 

UKMO shows Christmas Eve as a rather cold and windy day with gale or severe gales across the North and West in particular with frequent showers giving hail, thunder, sleet and snow in places.

 

GEM shows very unsettled with very deep Low pressure encircling the UK with some very potent small centres delivering very heavy rain and strong winds for all at times. It will become more generally less mild with some snow at times over the hills.

 

NAVGEM tonight shows a very wet Christmas too with low pressure spiraling across the Atlantic and the UK with heavy rain and severe gales with sleet or snow showers at times over the hills.

 

ECM tonight shows plenty of wind and rain over the Christmas week with severe gales at times and plenty of rain with wintry showers over the hills at times, especially across the North.

 

The GFS Ensembles show a sine wave pattern indicative of a very mobile and Atlantic based weather pattern. There will be plenty of rain with local flooding issues if some of the charts verify and some colder interludes too when some sleet or snow showers could fall over the hills.

 

The Jet Stream shows the flow continuing more or less unabated across the Atlantic and across the British Isles for the reliable future.

 

In Summary there seems no real letup now in the very unsettled and potentially stormy spell of weather which will take us through the Christmas period and up to the New Year. Although never technically very cold at any point the volatile nature of the weather will result in some unexpected weather events to show up, be it snowfall or thunder, lightning hail and even mini tornadoes. Wind damage will be feasible at times ad most importantly with continual heavy rain events occurring there will be an increasing risk of flooding as rainfall totals rack up quickly over the next week or so.

[Newberryone]

t240 looks better with high pressure edging up maybe bringing an end to all these deep lows as we close out 2013

 

 

 

Not a lot going on at 240hrs on ecm nh chart wise tbh so the unsettled theme continues into the new year .

 

 

That Azores high must be Irish, when you want it in summer it struggles to play ball and then likes to rear its head in winter, meh.

All open to interpretation of course but conflicting views nevertheless with regards to the last frame of the latest ecm op update.

I feel there's a relatively high chance this modeled high down to the southwest would in all probability setup shop close to the southeast of England, settling things down to an extent there but for areas closer to the northwest, especially Ireland, a continuation in the unsettled theme, albeit less intense.

[Summer Sun]

The ECM ensemble at t240 isn't going the Op's route in building pressure from the south, though winds would at least be lighter than previous days

 

 

Op

 

Edited December 18, 2013 by Summer Sun

[PolarWarsaw]

I think it's fair to say that there is 1 word that can sum up the models at the moment and that is 'unsettled'. Personally, if it's not going to be cold I hope it rains all day, every day for the remainder of winter! The Mildies can be comfortably warm, but miserable and wet that way!  The last month or so has been the proverbial 'bake a cake and eat it' for those who enjoy mild weather and I think it's fair to say - that's no longer 100% case! Really looking forward to the potential wind, squall, hail, snow and rain in the next 7-10 days as they at least keep things interesting! 

 

The outlook, sadly - doesn't look great for Coldies, not until 2014 has arrived anyway.

[Cloud 10]

A pretty scary 12z ECM ensemble mean chart for boxing day.

 

 

 

Must be some extreme solutions amongst the 51 ensemble members.

[Man With Beard]

Not much change on ECM mean from this morning, still 955mb close to Scotland around Christmas. While this remains the same, the potential for severe depressions to pass over the country persists. The period 23rd-27th December still very much in danger of seeing a country-wide storm (or two) I think.

 

[winterof79]

A pretty scary 12z ECM ensemble mean chart for boxing day.

 

EDM1-192.gif

 

 

Must be some extreme solutions amongst the 51 ensemble members.

Yes but here is todays

http://modeles.meteociel.fr/modeles/gfs/runs/2013121818/gfs-0-6.png?18

EDM1-192.gif

Not as vigorous really.

[johnholmes]

well my comment about the 8-14 from NOAA needing to show a similar idea to the 6-10 has been given this evening.

Just how much we can rely on the two I am not sure but they are consistent over the last 2-3 days. It is about the date that the 8-14 should have picked up on the 6-10 day idea if there was to be any credence in the evolution that the 6-10 and ECMWF-GFS have shown for 2-3 days.

No, don't get too excited, not a pettern change but it does look like a fairly marked change in temerature levels at 500mb, from 540-546DM to around 53DM now being redicted over the Channel area. The flow at 500mb, with an actual centre drifting SE of Iceland towards NW Scotland drops the speeds up there and for a day or two perhaps increases them in the south. This will perhaps have the effect of moving part of the surface lows further  south or possibly some kind of secondaries developing south of a main surface centre near the NW of the UK.

All very tentative but the mobilty slowly easing down and both upper and surface temperatures easing down as well. This obviously increases the probability of some snow to lower levels at times. Don't expect any detail from this post though and as to how long then, timing suggests this idea evolving over the next 4-5 maybe 6 days and then around for a further 3-4. Beyond that who knows.

link to NOAA outputs below

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

Edited December 18, 2013 by johnholmes

[Frosty.]

If I only had 1 christmas wish it would be that P8..GEFS 12z verified, it's a stunner from T+192 hours onwards..it speaks for itself and shows what could happen if the jet is forced far enough south..wintry heaven...however unlikely it is, it's there so i'm showing it 

[Cecil Hogmanay Melchett]

NAE 18Z still going for a decent hit for NW England and Yorkshire tomorrow.

Interesting!

[winterof79]

NAE 18Z still going for a decent hit for NW England and Yorkshire tomorrow.

Interesting!

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2013/12/18/basis12/ukuk/prty/13121918_1812.gif

 

We shall see.

[weirpig]

NAE 18Z still going for a decent hit for NW England and Yorkshire tomorrow.

Interesting!

yep and wales and parts of the midlands however short lived

[Cecil Hogmanay Melchett]

Was really hoping Fergie might pay a quick visit tonight to give us a heads up for tomorrow.

 

Anyway,im obviously not expecting a winterwonderland but falling snow would be nice in December,i need my FIX!!!    

 

Blast I must have been looking at 12z nae because the 18z is pants for said areas.

Roll on July...

Edited December 18, 2013 by happy days

[Due South]

GEFS could be onto something FROSTY. The time frame fits into someone's forecast, and it ISNT Madden's. Expect the Models to start picking up on the signals for JAN 1st-3rd.

[Cecil Hogmanay Melchett]

yep and wales and parts of the midlands however short lived

I was looking at 12z nae,18z is carp for my area,another 11th hour downgrade as the snowshield is obviously in good working order,not that it needs much maintenance this month.

[Ali1977]

GFS going for Xmas eve snow quite widely....and colder 850s

[johnholmes]

I was looking at 12z nae,18z is carp for my area,another 11th hour downgrade as the snowshield is obviously in good working order,not that it needs much maintenance this month.

my area=where please?

[Gaz1985]

NAE 18Z still going for a decent hit for NW England and Yorkshire tomorrow.

Interesting!

 

It looks like one of those borderline events when places above 200m may well see a slight temporary covering but most of us see sleet.

 

[Cecil Hogmanay Melchett]

my area=where please?

lol john I had this conversation with you last winter,and the one before,near Oldham next  town to hudds.

Edited December 18, 2013 by happy days

[bluearmy]

 

thas a pretty astonishing chart. look at those mean heights !!  i dont recall seeing anything like that before.  of course the thicknesses are tempered by the very low surface level pressure levels but i still think we will see a lot more wintry stuff beyond xmas than some on here envisage.

Edited December 18, 2013 by bluearmy

[Cecil Hogmanay Melchett]

610day.03.gif

 

thas a pretty astonishing chart. look at those mean heights !!  i dont recall seeing anything like that before.  of course the thicknesses are tempered by the low heights but i still think we will see a lot more wintry stuff beyond xmas than some on here envisage.

Would that be classed as cold zonality nickl?

[johnholmes]

lol john I had this conversation with you last winter,and the one before,near Oldham next  town to hudds.

 

ta, I will try and remember but for the life of me I cannot understand why you don't put your town in your avatar, are the police looking for you or something?

[NorthernRab]

lol john I had this conversation with you last winter,and the one before,near Oldham next  town to hudds.

 

Top drawer - pop it in the location part of your profile please?

[mountain shadow]

Christmas Eve shaping up well for the North West...

http://cdn.nwstatic.co.uk/gfsimages/gfs.20131218/18/138/prectypeuktopo.png

I'm dreaming of a...