Model Output Discussion 1200 hrs 30/09/14

[johnholmes]

 

Cheers

S

 

a 'like' of 24 posts there Steve, well earned in my view, worth reading for anyone who has not read it along with the well ilustrated charts.

We have our differences Steve come winter but if you post charts like that I could become a convert!

[chionomaniac]

a 'like' of 24 posts there Steve, well earned in my view, worth reading for anyone who has not read it along with the well ilustrated charts.

 

I agree John and Steve what you highlight is also why everyone should look at the hemispheric pattern rather than just looking at the Atlantic sector. Quite often it is very difficult to visualize the global flow patterns and you have described this very well. It is patterns like this, that come winter, get the experienced cold weather watchers excited, because they exude potential further down the line.

[Frosty.]

Last night's Ecm 12z op run @ T+240 hours caused a bit of a stir in here but I don't think this morning's 00z will, much as yesterday's 00z didn't either. Unless I am missing something, the ecm 0z shows a generally mild outlook for the south, an unsettled blip for a time next week but thereafter, pressure rises across the south so it becomes predominantly fine, for the north it looks windier and more unsettled with lower heights to the NW and occasionally cooler.

Edited October 18, 2014 by Frosty.

[gottolovethisweather]

Evening All-

 

Following on from the post in the OPI thread the models do give us some indication of what the jet is doing you just need to identify the signals.

 

The UKMO 144 is a good case in point.

 

UKM144.gif

 

 

In Black- Cut off lows, all around the globe. Showing the jet is digging south in multiple locations allowing in some cases for snow to reach lower lattitudes. When you get a sinuous jet the lows you will see a continuous easterly progression of lows in all quadrants.

 

In Red- A shallow ( in terms of heights ) high pressure over the pole, but enough to steer low pressure systems into the mid lattitdues, remember the long term October mean ( especially late in the month) will show the pole having its lowest heights around 500 decameters, so the high is indicating higher thicknesses ( & from our feedbacks we know higher thicknesses usually indicate a warmer stratosphere )

 

In silver: 2 weak area of vortex with small areas of low heights, quite detached from each other & showing no signs of stabilizing & circulating East. Also a nice ridge moving into the pole over scandi which at this time of year is unusual when again the westerlies should be penetrating all the way towards Western Russia.

 

In Orange - Lastly the reverse flow around 3 quadrants of the globe which shows ( or should show) a weak zonal wind as the overally flow is more or less Easterly. That's inverse to the October average flow.

 

Complete the same exercise on the ECM& you see even more distortion of the pattern. remember the more extreme the indices the more extreme the weather becomes V the norm.

 

ECM240NH.jpg

 

the ECM is a work of art if your looking for extreme indexes, the jet is all over the show meandering around the globe & a very strong negative zonal wind.

These are the quadrants I use for Winter...

 

Also the comment that was used the other day that the UK isn't effected by anything downstream is almost laughable when the azores high is linked to developments back around the globe....

 

I will leave you with the GFS NOAA AO ensembles from 00z earlier-

Interesting to see what they look like tomorrow...

 

AO MEAN.gif

 

for reference here is a +5 AO one of the most positive charts you can get-

 

just 1 cut off low & a jet with maximum easterly progression.

Nov1993.png

 

Cheers

S

 

That is one grand explanation of how things work at a global level, I will ask somebody in the moderating section to perhaps grab this post and place it in the netweather learning area as its certainly assisted me and I've been here since 2007. 

[Cloud 10]

A bit off topic,but just a heads up for anyone using the meteociel site to view the models this morning as i 

keep getting a pop-up telling me that i need to update adobe flash player,but this is in fact a computer

attack which was blocked by my anti-virus software.

 

I f anyone else gets the Adobe page DO NOT click on anything on it but either close down your browser or restart your computer.

[Iceaxecrampon]

Bit gusty for Alba on Tuesday with ex-Gonzo.

 

 

Hang on to the Kilts - brisk - but seen a lot worse at present output.

 

 

Ian

 

 

[Summer Sun]

GFS again showing some settled warmer weather developing next weekend and into the following week after a wet and windy spell on Tuesday from ex Hurricane Gonzalo

 

 

High pressure still in control as November arrives but its a cooler high as we pick up an easterly flow

 

Edited October 18, 2014 by Summer Sun

[Captain Shortwave]

No point even contemplating it, but the GFS low resolution is a barrel of laughs. A 70F southerly at the end of October before temperatures tank under a monster Scandi high. And to finish it off

I wonder what would happen next 

 

In more realistic terms, there is definitely a trend to anchor the tropospheric vortex over Greenland, with cold air spilling into the Atlantic, the end result does look potentially like a UK high as the jet simply rotates around the Greenland blob and back towards the Arctic circle. My thoughts for November and indeed December were for a more anticyclonic regime, and it looks like the models might be edging that way.

Edited October 18, 2014 by Captain shortwave

[bluearmy]

I always urge viewing the runs on a NH profile at this time of year. Nothing exciting from a wintry perspective is likely within the next few weeks so looking at the Atlantic is likely missing the bigger picture which will drive what is probably coming through November and into December.

that ECM ens anomaly profile for the beginning of November looks ok from a coldie perspective. no sign of a developing compact vortex there. plenty of evidence that further wave breaking into the strat is likely to continue.

[cyclonic happiness]

Very exciting looking 06Z run in deep FI, must be the first really wintry looking chart that we've had this autumn?

 

A great big, fat HP sitting over the UK , which then skulks off to Greenland and leaves us open to a very cold northerly straight from the pole. Plus the polar vortex is in Eastern Siberia......oooh err! I think I just had a chartgasm ><         

[Frosty.]

oooh err I like the last frame of the Gfs 06z op run today, high pressure pulling west and the mother of all Northerly's about to bring an early taste of the Arctic, always a refreshing thing to have  wish it was T+24 instead of T+384 but hey, we can't have everything can we.

 

Like I always say, the best porn is cold porn  

Edited October 18, 2014 by Frosty.

[legritter]

As usual gang ,the very far outlook is very tasty for some .But it looks like we will be graced by action weather looking at current charts ,so not boring, typical Autumn fayre ,Frosty 009 get the Stellas in ,i,ll have a half .   :drinks:iv just got back from southern italy but i have been popping in to our great forum ,cheers .

Edited October 18, 2014 by legritter

[Frosty.]

Tonight's GEFS 12z perturbations, actually I think all of them are emphatically going for a nationwide anticyclonic spell beyond the next 8 days so it's no surprise to see such a settled mean through FI, the north of the uk takes longest to improve and where the high becomes centred will make all the difference in terms of cloud amounts, wind speed and temperatures but there looks like being a good chance of fog eventually becoming a major hazard through late october / early  november and turning cold enough at night for slight frosts beyond next week. Today's met office update is also going for an increasingly settled further outlook for at least the south of the uk.

Edited October 18, 2014 by Frosty.

[Newberryone]

Seems almost inevitable now we're going to see far more than just a transient ridge come next weekend. Last week of October ending on an extremely quiet note with above average temps. Turn of the month does hold the promise of another PM incursion. 

[Captain Shortwave]

All models are now going for an increasingly anticyclonic outlook in week 2

GFS

ECM

GEM

Some support from the ensembles too

Depending on the position of the high will determine the kind of conditions we will experience. We could see unseasonal warmth or increasingly chilly conditions under an inversion.

[ANYWEATHER]

Gonzalo has a big impact on the Uk  from late Monday into Wednesday, not sure the details will be correct at the moment, but this system will give the First Big Cold Blow of the season, a Stark reminder that we are in Autumn, it will feel very cold for all on Tuesday with a significant wind chill, proper Autumn weather for all, at least for two days!!    

[Frosty.]

An Anticyclonic end to the Ecm 12z tonight and another feature of this run is that it's not going to be mild all the time, far from it, there are some rather cold feeling days during this run, next tuesday for example being unpleasant with gale force nw'ly winds and rain with max temps around 10-12 c, the SE corner ends up with a relatively chilly and brisk Easterly flow by T+240 hours and there is now solid cross model support for high pressure to build in from the southwest towards the end of next week so it looks odds on that our weather will be turning settled with an increasing risk of fog and slight frosts but fine pleasant days with light winds.

Edited October 18, 2014 by Frosty.

[Barry12]

Much colder at day 8

 

 

Edited October 18, 2014 by Barry95

[Summer Sun]

Much colder at day 8

 

 

 

You are aware thats the 00z run from yesterday? though today's 12z ain't that much different

 

[Captain Shortwave]

Might as well add the ECM ens to the list

Lets hope for a nice sunny high rather than a cloudy one.

[bluearmy]

very large spread across the polar field by day 10, especially so the asian side. the anomolys continue to prog higher than average heights in this region.  we do look like receiving the benefit of a nice block week 2. events over the polar field look less easy to predict.

[Nick F]

An update to my synoptic outlook discussion in a blog I started yesterday. Focusing on soon-to-be ex-Hurricane Gonzalo and what may happen thereafter.

 

Discussion can be seen in full here: http://www.netweather.tv/index.cgi?action=news;storyid=6230;sess=

 

*UPDATE 2200z Saturday 18th October*

 

Hurricane Gonzalo continues to move rapidly northeast tonight at around 31knts as it becomes embedded in the strong southwestelry flow on the eastern side of upper trough across NE USA. Over the next 12 hrs Gonzalo makes the transition to strong extra-tropical depression, as it moves over sub 20C SSTs and encounters increasingly strong southwesterly vertical wind shear. This extratropical depression is expected to be just east of New Foundland at noon on Sunday, at around 977mb. The depression then turns east-northeastward over the far north Atlantic, pushed along by a strong westerly polar front jet stream towards the British Isles, filling as it does so.

 

GFS and, to lesser extent, ECMWF, then suggest the depression then deepening again and tracking more NE in direction during Monday, as a sharpening shortwave trough digs SE from southern Greenland towards the low, causing it to deepen as large scale ascent occurs ahead of the trough. The low also falls increasingly under the developmental left exit of the strong Atlantic jet on GFS, which further helps to deepen it. So there is some concern that this low could have some severe impacts on the UK, as it moves NE close to or over Scotland early Tuesday morning, the exact track and depth still uncertain at the moment. GFS indicates winds will be strongest when they turn northwesterly on the southwest flank of the low moving northeast, strongest winds across the northwest Tuesday afternoon, with northwesterly gusts of 60-70mph before gusts of 50-60mph spread SE across Scotland, N. England Tuesday evening/night then E Anglia and into the North Sea Wednesday morning. Heaviest and most persistent rain likely Tuesday morning, followed by frequent showers across the north and west as winds turn northwesterly.

 

A brief ridge builds across the south on Wednesday, bringing fine weather here, remaining more unsettled and windy in the north. But pressure/heights fall again from the NW Thursday and Friday, bringing more in the way of cloud and some rain to end the week and into Saturday 25th. Still enough continuity from GFS and ECMWF to have some confidence thereafter for a strong ridge to build from the SW starting Sunday 26th, in response to an amplified trough coming out of NE USA/ E Canada that digs deep across the NW Atlantic. Although exact position of the ridge far from being resolved this far off, increasing chance last week of October could end on a more settled and dry note, following the current unsettled spell.

 

Latest ECMWF and GFS H500 comparison highlights the high pressure block building from the SW for last week of October quite well:

 

 

As does the CPC Prognostic 8-14 dayer:

 

Edited October 18, 2014 by Nick F

[Frosty.]

I have high hopes it will be a sunny anticyclone with fog and frost once the unsettled spell subsides later next week. Next Tuesday stands out as being a stormy day with potentially severe nwly gales and heavy rain but thereafter we will see high pressure building in from the sw with northern UK last to improve.

Edited October 18, 2014 by Frosty.

[bluearmy]

Another set of gefs which show more appetite to decimate the p/v in respect of it being a single strong and compact hemispheric feature by early November. interesting times ahead for those wishing to see how a weak vortex in mid to late autumn affects the drivers of our weather come December and January.

[Frosty.]

I'm on sleet and wet snow patrol this morning, I went through the Gfs 00z op run frame by frame and found some would you believe it..ooh err missus there might be a bit of the white stuff blowing around in the north with polar maritime incursions

 

This run looks surprisingly unsettled throughout, high pressure never really gets a foothold which is interesting considering how every 12z gefs perturbation last night showed high pressure domination in FI but for the most part we have a windy and unsettled gfs 00z this morning, especially for the north.