Model Output Discussion - 18z 31/10/15 onwards

[Paul]

A good example of the N/S split next weekend

Chart weatherbell

 

In a world where blue = milder than red at least

 

While it's going to be a shock to the system in Scotland, it's actually just temps ending up near to average as well.

 

 

Longer term, the euro high is finally getting squeezed a bit.

 

Edited November 10, 2015 by Paul

[Frosty.]

The Gfs 00z op is an extremely unsettled run and there are some large variations in temperature from day to day, especially across scotland. it's certainly not constant mild every day / night, some days / nights are colder with wintry showers on northern hills and even leading edge snow on the hills / mountains in scotland as vigorous lows swing in on a more southerly track at times. There is barely a break between depressions, next tuesday shows a small ridge crossing the uk but for most of the time it's a very disturbed pattern in the weeks ahead.

[knocker]

Midday

 

[johnholmes]

To me it seems the overall pattern for a couple of weeks is an unsettled westerly over the Atlantic and into Europe. So a mix of Tm and Pm air for most with the Pm air most noticeable and most frequent for more northern parts. If you like a nw-n/se-s split. Possibly some pretty deep lows passing between Iceland and Scotland at times so windy as well in association with them.

[knocker]

Yes sure looks that way. This morning's anomalies may disagree a little over the HP NE Canada but the main ingredient the positively tiled Atlantic trough is in place. Potential ( I can't believe I've used that word; must put it down to a senior moment) for some quite nasty weather particularly in the north.

http://www.tropicaltidbits.com/

 

[cheshire snow]

It would have been interesting to see the next two frames on

This Morning ECM,way out in FI at T240 the -5 uppers reach

Northern Scotland,with lots of cold air upto the NW of the UK

C.S

[carinthian]

Lots of difference in the up stream pattern compared to this time last year. Could be a complete reversal to the previous N. American winter. Already we see a strong development of Gulf Alaskan Low driving in unsettled conditions to Western Canada and the Rockies States. All this after a drought of a summer here. So the El Nino creating a swift change in this location. High Pressure holding over the Great Lakes operating in tandum with the Euro high and keeping the cold at bay for the great populated centres of both the Eastern USA and Europe. Variables will come into account, mainly as I see it the low sea temperatures persisting in much of the NW Atlantic Ocean to include Baffin and Labrador Seas and the continued forecast to show negative anomalies of the coming 30 days. Westerlies may dominate for sometime yet but the variable I highlight and a strengthening High over NE States/ SE Canada could easily change the dominant winter patterns as shown for the previous two over both sides of the Atlantic.

C

In reference to the post I sent yesterday, I have attached the latest Upper Air Analysis Chart for North America, this one at 500hpa. It really shows a huge switch around from what we had over there at the start of the winter season. The Alaskan Low meeting the Arctic Airmass, a marked trough pushing through the great divide into the Western States, plenty of snow this time for the Rockies and Coastal Ranges. On the other side of the jet, warm conditions locked to the south of the Great lakes/. Whether this up stream change has an effect on the Europe start of winter, I am not sure, but an interesting reversal in synopics to start the winter. The colder than average sea temps in the NW Atlantic will have no effect on the jet stream but more pronounced effect on surface air flow temps, especially Pm .

C

Edited November 10, 2015 by carinthian

[stodge]

Morning all

 

A rare chance for me to have a quick look at the model output with the 06Z rolling out and the immediate observation from this part of the world is how fixed the current pattern seems to be.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015111006/gfs-0-6.png?6

 

The current situation with the HP over France and a longish fetch SW'ly bringing some very mile TM air from the mid-Atlantic up over the British Isles. Little surprise to see above average temperatures given all that.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015111006/gfs-0-120.png?6

 

Roll forward five days and the differences are subtle at most for the south. Signs of the HP weakening perhaps but the overall synoptic situation much the same with very mild TM air over the south.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015111006/gfs-0-192.png?6

 

At T+192 the decline is more evident and the transition to a more cyclonic regime with occasional bursts of PM air seems likely. Follow the 1020HPA isobar through the run as it gets puahed further and further south and the 850s start to taper off as well.

 

None of this means anything cold on the horizon but the trend to a gradual falling off in temperatures to late autumn averages combined with a more unsettled synoptic picture seems at last to be moving into low-res.

 

http://modeles.meteociel.fr/modeles/gem/runs/2015111000/gem-0-168.png?00

 

This morning's GEM at T+168 - not quite so progressive but the trend is there and GEM FI suggests PM air in the ascendancy into FI.

[pip22]

There is a potential cold snap/spell could happen between the 19th and 22nd of this month.

 

 

 

 

 

 

 

 

 

 

I know its a bit brief and far out but it have plenty of time to upgrade it to a more long lasting spell of cold or just nothing. We'll shall see in the next few runs.

Edited November 10, 2015 by pip22

[Polar Maritime]

Yes the GFS 6z certainly shows a stronger Pm influence into the run, As Low pressure systems take a more Southerly track for the last 1/4 of November. The ECMWF also seems to show this pattern for the same period.

Edited November 10, 2015 by Polar Maritime

[Frosty.]

The Gfs 6z shows some nice Pm shots and some frosty nights in calmer interludes between atlantic depressions, the thing that pleases me most is the uk losing the influence of the euro slug anticyclone and now we can look forward to a more traditional, seasonal spell of late autumn weather with alternating Tm / Pm airflows, plenty of rain, wind and also a risk of wintry showers at times, especially on northern hills.  

Edited November 10, 2015 by Frosty.

[Singularity]

ECM's 00z det. output for next Tue-Wed (see below-left) illustrates the sort of thing that I suspect we'll have to watch out for in the coming 2-3 months; an Atlantic trough extending south in the middle of the North Atlantic - toward the Azores - and allowing an associated low pressure system to take a swipe at the UK from south of west. The low doesn't deepen enough to be damaging on this particular run, but the threat is there as the thermal gradient becomes pretty large at times in the N. Atlantic (helped by the SST anomaly pattern).

 

Another event type to look out for is areas of low pressure developing west of the Azores, triggered by the more active subtropical jet occurring in response to the strong El Nino event. These are likely to promote a build of high pressure through Europe and there is a low chance that they could then run NE and pass close enough to the UK for a strong pressure gradient to bring some strong winds as well as the attendant heavy rain. The ECM det.+240 chart (below-right) shows a version in which a low has developed but then matured very quickly while still SW of the UK. That's the variant that lends the most support to a Euro High, and strong El Nino winters tend to see quite a lot of such developments - hence the expectation of generally positive height anomalies over Europe for at least Nov-Dec.

 

[MPG]

Yes the GFS 6z certainly shows a stronger Pm influence into the run, As Low pressure systems take a more Southerly track for the last 1/4 of November. The ECMWF also seems to show this pattern for the same period.

Where's the PV? Not setting up in its usual place so far this winter going by your charts.

[stodge]

http://modeles.meteociel.fr/modeles/gfs/runs/2015111012/gfs-0-126.png?12

 

The first point at which the 1020MB isobar leaves the south coast so those of us "dahn sarf" have five days or more of the mild TM sourced air in front of us.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015111012/gfs-0-240.png?12

 

Perhaps a hint of the jet starting to move back south.

[SLEETY]

yes signs of a change to more seasonal temps soon  as well

[Frosty.]

The Gfs 12z shows cold air pushing south at times from next week with even some snow across scotland as atlantic lows swing into the uk on a more southerly track. I found this to be a very interesting run.

[damianslaw]

Some stirrings perhaps that we may be about to see a pattern change of sorts, with the development of stronger deeper low pressure systems from the NW finding it easier to penetrate the country on a more southerly track pushing the euro high aside and ushering in a more traditional late autumnal pattern of alternating tropical maritime and polar maritime air. GFS showing the long wave trough digging far south into the mid atlantic this will have the effect of enabling secondary low development to the SW of weak ridge development over southern parts of the country with the north exposed more to polar maritime shots. Not a change to anything significantly cold, but far more seasonal and average for the time of year, and hopefully something far brighter at times than the last week which here has delivered a complete gloom fest with no sunshine.

[pip22]

I think on Monday and Tuesday next week we could see the first cold snap according to the latest 12z GFS:

 

 

 

 

 

 

Also from Thursday next week  interesting charts which could push more colder weather southwards:

 

 

 

 

 

I think the cold air mass is getting the upper hand and theres more next weekend:

 

 

 

 

 

It looks to me it is improved from the last run that I posted this morning.   It looking promising to me.

[nick sussex]

Some differences between the big 3, the GFS/ECM versus the UKMO at T144hrs.

 

The UKMO phases both those lows whereas the GFS/ECM keep them separate with a stronger ridge to the nw. Its still a struggle to get the cold air south even with the latter.

 

The ECM then goes onto bring the Euro high back later and its output is being met with horror across the European ski resorts, we've seen over recent days the difficulty in moving the pattern sufficiently se, a few ECM operationals did suggest that might happen but that was at day 9 and 10 and we're now seeing these trends dropped.

[blizzard81]

The one thing I noticed about the 12z ECM run tonight is how the polar vortex shrinks throughout the run I know there is plenty of time for it to power up but wasn't it meant to have happened by the final third of Nov? If tonight's ECM is anything to go by, the vortex actually weakens throughout the run.

Edited November 10, 2015 by blizzard81

[ANYWEATHER]

Evening! The Wet and Wild Ride is just about to start for the United Kingdom after many weeks of very benign conditions....  The Jet stream powers up across the Atlantic and creases the Euro High. I will stick my head out and say the end of November will be stormy and much colder . probably a bit below average, into December  anyway a pasting for the mountains of North Wales , Northern England and Scotland... Of course the  will be in the detail.....

Edited November 10, 2015 by ANYWEATHER

[blizzard81]

Interestingly the Trop pv is told to back away from its rightful home by a big Eastern seaboard high throughout the GFS 12z....However if notes from Strat thread are true could be an awesome but forlorn battle

The ECM day 10 shows the vortex nowhere near as powerful or widespread as that GFS day 10 chart.

[bradymk]

Some differences between the big 3, the GFS/ECM versus the UKMO at T144hrs.

 

The UKMO phases both those lows whereas the GFS/ECM keep them separate with a stronger ridge to the nw. Its still a struggle to get the cold air south even with the latter.

 

The ECM then goes onto bring the Euro high back later and its output is being met with horror across the European ski resorts, we've seen over recent days the difficulty in moving the pattern sufficiently se, a few ECM operationals did suggest that might happen but that was at day 9 and 10 and we're now seeing these trends dropped.

 

It seems to have been happening for a while now in terms of the euro high. Hints of it leaving at day 9 and 10 before it holds on as we get closer to the time. The ENS mean though a lot better than the op and does keep the high more to the south.

 

Op Mean                                     ENS mean                   

 

 

Latest EC seasonal. Not one for seasonal models though.....

 

[Summer Sun]

The ECM ens shows Its low pressure rather than high pressure which becomes the main player in our weather as we move into the 2nd half of the month temps falling back towards the seasonal average and more changeable weather with a risk of gales at times and some wintry showers on the high ground in northern areas the south has the best chance of seeing some milder air which could still push up from mainland Europe this is more likely early on in the period

 

[Hotspur62]

Latest Cohen AO forecast

https://www.aer.com/science-research/climate-weather/arctic-oscillation

 

Just had a quick read and very interesting read. If  I have read correctly it looks like the mild theme will continue for Europe including the UK for the rest of November and into early December. Not good for the ski resorts and cold lovers but at the moment the El Nino looks to be an important driver atm. Gut feeling is winter will not get going till after New Year which ties in with some of previous El Nino years but this is a super strong El Nino so who knows. All interesting stuff !!