Model output discussion - 16th Nov onwards

[Polar Maritime]

The GFS shows the Low on Saturday a little further West.. Effecting more parts in-land.

Edited November 19, 2015 by Polar Maritime

[fergieweather]

I would be quite excited if I were in NE England right now after that Euro4 chart, hopefully the strong snow forecast will be maintained through this afternoon and evenings runs.

E4 considered by UKMO to be overplaying snow by around 40%. EC considered more realistic guide at present. Nonetheless, spatial signal for parts of N'rn UK and eg Lincs Wolds looks fine.

[Mair Snaw]

The GFS shows the Low on Saturday a little further West.. Effecting more parts in-land.

Yes interesting that small shift west bring more areas into the mix so to speak...

Edited November 19, 2015 by Polar Maritime
;-)

[Mucka]

E4 considered by UKMO to be overplaying snow by around 40%. EC considered more realistic guide at present. Nonetheless, spatial signal for parts of N'rn UK and eg Lincs Wolds looks fine.

 

Thanks Fergie, is that due to track, ppn rates or ppn type being miscalculated in your view? 

How about the Westward extent of potential snowfall from that feature?

[fergieweather]

Thanks Fergie, is that due to track, ppn rates or ppn type being miscalculated in your view? 

How about the Westward extent of potential snowfall from that feature?

Just discussing all that presently on conference with UKMO...will advise.

[Mucka]

Hmmm GFS definitely sniffing something/

120h and already building a ridge through Scandinavia.

 

 

More energy heading NE rather than SE as with 06z though.

 

UKMO a real eye opener at 144h

 

 

Will ECM show a phantom Easterly in FI this evening after a mundane zonal morning run?

Something is afoot though it seems.

Edited November 19, 2015 by Mucka

[fergieweather]

Just discussing all that presently on conference with UKMO...will advise.

Ok so in summary, W'Ward extend of occlusion and ppn envelope has continuing doubts in any case, but more 'acute' GFS 12z solution re this is not wholly trustworthy, as Ops Centre continue to see upstream errors in that model into the Atlantic, meaning evolution of the low early Sat not handled the same as eg EC or UKMO-GM. Still no real concerns over lowland snow sticking in southern England (depth temps and RST's too high; good low level mixing in wind preventing these falling to 0C in south). Hope that all helps - cheers.

(PS view may change once we see 12z EC ENS and MOGREPS)

Edited November 19, 2015 by fergieweather

[bradymk]

umm hello UKMO 144.

 

 

Difference between that and ECM 168 chart yday quite different

 

 

 

GFS cool middle of next week too. High to the east looking quite strong....

Edited November 19, 2015 by bradythemole

[TSNWK]

Hmmm GFS definitely sniffing something/

120h and already building a ridge through Scandinavia.

 

 

More energy heading NE rather than SE as with 06z though.

 

UKMO a real eye opener at 144h

 

 

Will ECM show a phantom Easterly in FI this evening after a mundane zonal morning run?

Something is afoot though it seems.

Good evening Mucka.. What has caused a raised eyebrow on that UKMO 144.. Looks of me as presure is low over Greenland with the Azores high about to drift up towards us.

[Polar Maritime]

Ok so in summary, W'Ward extend of occlusion and ppn envelope has continuing doubts in any case, but more 'acute' GFS 12z solution re this is not wholly trustworthy, as Ops Centre continue to see upstream errors in that model into the Atlantic, meaning evolution of the low early Sat not handled the same as eg EC or UKMO-GM. Still no real concerns over lowland snow sticking in southern England (depth temps and RST's too high; good low level mixing in wind preventing these falling to 0C in south). Hope that all helps - cheers.

(PS view may change once we see 12z EC ENS and MOGREPS)

 

Yes Ian, Still lots of uncertainty regarding the track/movement of the Low for Saturday.  

Edited November 19, 2015 by Polar Maritime

[Captain Shortwave]

Day 6 charts

UKMO

Chilly north to north west flow with wintry showers down coastal fringes.

 

GFS

 

A much quicker evolution with respect to the trough early next week attempting to develop a cut off feature south of the UK pulling in a chilly easterly flow, albeit not much wintry potential at the moment.

 

Whilst looking quite different, both models have the same idea of digging a trough sharply south during the middle of next week with heights remaining in the Atlantic* for a time and a new cell developing over western Russia.

 

Considering the likely Atlantic assault at the end of next week in response to a strong ridge developing over the Pacific then it will be interesting how things pan out over Europe in respect to how the assault from the west takes place as the Azores high inevitably gets flattened into oblivion by the strengthening jet.

[chrisbell-nottheweatherman]

Presumably, the probable flattening of the Azores/Bartlett High by the Atlantic jet as a consequence of Pacific ridging would see the incredibly mild conditions of recent weeks disappear for the time being?  Regarding the GFS weak easterly; with SSTs being high at present, how much stronger would the easterly have to be to enable coastal showers?

[Mucka]

Good evening Mucka.. What has caused a raised eyebrow on that UKMO 144.. Looks of me as presure is low over Greenland with the Azores high about to drift up towards us.

 

Hi.

The burgeoning ridge of high pressure up through Russia/Scandinavia and the split energy with some undercut.

Quite possible the low behind you mention would begin to disrupt and be forced South forcing more WAA into the mid latitudes and reinforcing high pressure to our E/NE.

It is not that it offers immediate wintry potential but it does offer some going forward.

All my opinion of course.

 

GFS 12z 10 day chart decent consistency with the 06z only with the pattern backed West - a good trend if that is what it becomes.

 

Edited November 19, 2015 by Mucka

[Frosty.]

Great to see an early taste of winter this weekend from the Gfs 12z with a risk of snow up and down the UK including the southeast and temperatures struggling in low single digits celsius, we coldies have something to smile about at last!

Edited November 19, 2015 by Frosty.

[radiohead]

Anyone watching the 12Z GEM?

 

Edited November 19, 2015 by radiohead

[TSNWK]

Hi.

The burgeoning ridge of high pressure up through Russia/Scandinavia and the split energy with some undercut.

Quite possible the low behind you mention would begin to disrupt and be forced South forcing more WAA into the mid latitudes and reinforcing high pressure to our E/NE.

It is not that it offers immediate wintry potential but it does offer some going forward.

All my opinion of course.

 

GFS 12z 10 day chart decent consistency with the 06z only with the pattern backed West - a good trend if that is what it becomes.

 

Many thanks.. Great to see you back online..

[TSNWK]

Anyone watching the 12Z GEM?

 

One of the lesser models.. If ECM shows that, hen expect theist contact to increase. Objective trend from today is increasing heights to the east and the impact that is showing I'm regard to energy from the west..

It's winter folks and we have something to discuss

[pip22]

Scandy High!!

 

 

 

 

 

 

Then a polar maritime air coming in from Canada.

 

Edited November 19, 2015 by pip22

[Singularity]

That's quite an increase in the depth of the North Sea low on the GFS 12z det. compared to the preceding few runs. Substantial precipitation gets a lot further east but mixing in of less cold lower level air from the north sea means it only really falls as snow across the spine of the UK and even there it's pretty transitory in nature.

 

There's also no disturbance in the flow running south Saturday night so the run isn't being very kind to cold + snow seekers in the short term.

 

Mid-term, the run features a proper bit of trough disruption with a cut-off low dropping south to Iberia, allowing a ridge over southern Scandinavia to nose west to the UK. That keeps things rather chilly at the surface though nothing special - there's also no real cold pool to tap into over the near continent, though the low level air would certainly feel cold if it was pulled west.

 

As it is, the run as the Atlantic trying to pile up and over the blocking high, resulting in an intrusion of increasingly mixed-out Atlantic air, threatening 'cold rain' as some on here might call it. 

 

To avoid sounding too pessimistic (just realisitc, honest!), the tilt of the trough as of +216 (the run's still uploading on NW) is becoming negative, which encourages trough disruption and tends to allow blocking highs to back west so it's a very interesting situation from the American NWP model. 

 

 

If only UKMO was on board eh?

 

 

Yeah, I know - it takes some serious excitement to move my head away from level 

[Frosty.]

Hope the ukmo 12z is right about next week with another cold snap..fingers crossed. And closer range, nice chart showing snow risk on Saturday.

Edited November 19, 2015 by Frosty.

[chris55]

Very different 12z GFS in the mid term tonight!!

 

The quick return of a flatter pattern has been put into question.

 

Nice run to be honest.

[bluearmy]

Note the gfs op loses the strength of the blocking to our East precisely as low res begins .........

[TSNWK]

Note the gfs op loses the strength of the blocking to our East precisely as low res begins .........

Which I will take as a postive.

[Mucka]

Bearing in mind Fergies earlier posts Euro4 12z sticking with the strong snow signal for the NE of England for now.

 

 

Which is a little odd given DP's are above freezing 

 

 

Edit

cancel that, it was a cached version of 06z

Here is the latest 12z chart, sorry.

 

 

Unfortunately all rain by the time hits the SE (on this run)

Edited November 19, 2015 by Mucka

[Nouska]

The French high res output still brings the precip in as snow and shows a few cms for East Anglia and SE.

 

AROME    ARPEGE                      

 

48 hour accumulated total - probably not going to lie with ground temps and dew points.  

 

Edited November 19, 2015 by Nouska