Model Output Discussion 01/09/17

[comet]

8 hours ago, Snowy L said:

I remember Chiono explaining to me about what happened in 2010 as there was nothing in the stratosphere happening that could have indicated the tropospheric vortex being completely destroyed twice in November and December of that year.

 

Basically it was wave breaking in the troposphere, so a troposphere-led split of the tropospheric vortex.

 

BTW I am not suggesting we will get 2010-like conditions, just thought this is a useful example of how we can still get brilliant tropospheric synoptics without the help of the stratosphere.

There was warming in the strat prior to the cold spells of 09/10 and Dec 10. Also more importantly we had increased geopotential heights up to 30mb and above None of which is being shown in the strat forecasts.

Edited November 7, 2017 by comet

[Cheshire Freeze]

4 minutes ago, comet said:

There was warming in the strat prior to the cold spells of 09/10 and Dec 10. Also more importantly we had increased geopotential heights up to 30mb and above None of which is being shown in the strat forecasts.

Exactly. I can't see any support at all for any sustained high latitude blocking going forward.

[bluearmy]

3 minutes ago, CreweCold said:

Exactly. I can't see any support at all for any sustained high latitude blocking going forward.

How long is sustained Crewe?  I don't think anyone has suggested this upcoming neg AO phase will persist for weeks on end?  just assuming that the strat/trop will connect like lego bricks is just as wrong as assuming the ec 46 will verify.  fwiw, I only used it to day 28 as a tool to back up the current eps direction of travel.  I appreciate why you are playing devils advocate and also that, as steve alluded yesterday, the outcome for the second half November is likely to be less crazy than some recent GFS ops have been showing. However, to dismiss this upcoming neg AO phase before its begun can look a bit churlish - after all, this maybe the closest some of us get to decent winter sypnotics for the next five months!! 

Btw, GEFS AO stayed solidly neg, even on the 18z run

[Cheshire Freeze]

1 minute ago, bluearmy said:

How long is sustained Crewe?  I don't think anyone has suggested this upcoming neg AO phase will persist for weeks on end?  just assuming that the strat/trop will connect like lego bricks is just as wrong as assuming the ec 46 will verify.  fwiw, I only used it to day 28 as a tool to back up the current eps direction of travel.  I appreciate why you are playing devils advocate and also that, as steve alluded yesterday, the outcome for the second half November is likely to be less crazy than some recent GFS ops have been showing. However, to dismiss this upcoming neg AO phase before its begun can look a bit churlish - after all, this maybe the closest some of us get to decent winter sypnotics for the next five months!! 

Btw, GEFS AO stayed solidly neg, even on the 18z run

Sometimes you just 'know' Nick. Call it years of hard earned experience!

By sustained I mean something that sees us into winter proper. Had we had decent strat and long range modelling support, I'd be a hell of a lot more optimistic. 

[Jonan92]

Much better NH profile on the ECM run, compared to the GFS

[knocker]

The ecm has the wave(s) Friday/Saturday morning a tad further west otherwise the weekend much the same as the gfs. And although varying in detail next week, not surprisingly, following the same pattern,

[bluearmy]

18 minutes ago, CreweCold said:

Sometimes you just 'know' Nick. Call it years of hard earned experience!

By sustained I mean something that sees us into winter proper. Had we had decent strat and long range modelling support, I'd be a hell of a lot more optimistic. 

I agree that there is no strong evidence that high lat blacking will make it past the first week of December (despite what the ec 46 shows!). Of course how blocking and neg AO manifest themselves in respect of an amplified pattern affecting nw Europe is still unknown. At the moment we are seeing the ops closing the door on the hemispheric splits recently shown as they exchange chunks of residual vortex from Siberian to Canadian sides. this is to be expected but we should still see a height rise in the Greenland/Iceland areas as the end game as we approach the last third of the month. Whether that leads to a fleeting northerly or something more notable - who knows? 

Has anyone seen the updated ec seasonal for November ??

[BLAST FROM THE PAST]

Mid month looking very interesting on both GFS and ECM, indeed deep winter on GFS as it goes further but ECM sniffing at similar outcome not discounting a transient chilly shot around 11th .  So what I’m looking for is HP to W/NW and deep LP/displaced PV to come Over us and to our east to dominate last 10-12 days of Nov.  GFS may not be outlandish in the very wintry set ups in deep FI.....this month I believe could point to the rhythm of winter, with a burst of real cold from our N quadrant which may sustain for 10 days or so.

 

BFTP

[bluearmy]

Updated extended eps - steady as she goes

pwrhaps MWB could let us know later if there are any clusters still on a different page 

[Polar Maritime]

The GFS into Wk2 continues to show a cool sometimes cold Pm flow from the N/W, Turning Northerly at times as fronts pass with overnight frosts and rain turning wintry with elevation, temps avg or just below. A good snow builder for the Highlands in these setups, And should give a good start for Winter sports season up there.

 

[Man With Beard]

1 hour ago, bluearmy said:

Updated extended eps - steady as she goes

pwrhaps MWB could let us know later if there are any clusters still on a different page 

Clusters not quite ready yet but I've had a look at the individual members ... hmmm .... quite a lot of deep lows around Iceland at D10 this time - the general development thereafter is still to develop heights over Greenland/Iceland but the low pressures seem closer to UK/France rather than Italy, and heights a bit stronger over S Europe on this one when compared with recent ensemble sets. So I think the overall story will be a northern influence but not quite the extremes that some of yesterday's output indicated. Still, just one run, and probably a few days before any detail can be nailed down for the period of interest for coldies, which I put at the 16th onwards.

[Man With Beard]

and here's the EC clusters for D10/D12/D14

    

they show the tendencies I mentioned in my previous post nicely; troughing betwen Iceland/Scotland is slightly favoured at D10, a general increase of heights to the north during the period and the low heights tending to be close to the UK.

But the spoiler cluster I mentioned yesterday has gone - by D14 all clusters have some sort of heights running from Greenland down into the Atlantic. 

[ICE COLD]

This looks better ? 

[Nick F]

3 hours ago, knocker said:

The ecm has the wave(s) Friday/Saturday morning a tad further west otherwise the weekend much the same as the gfs. And although varying in detail next week, not surprisingly, following the same pattern,

Said wave appears to be the remnants of now Tropical Storm Rina currently over the W Atlantic before swinging round the north side of the Azores before dropping SE across Ireland and UK Friday night/early Saturday. EC tracks it further south across SW UK and weakens it quickly. Could bring a lot of rainfall Friday night though, especially Ireland. Chart credit: wxcharts.eu:

Looking at the rest of the 06z GFS op coming out, the well-advertised brief N to NWly developing late weekend could bring some snow to the Scottish mountains and tops of northern hills of England. The 500mb vortex over Greenland and Iceland re-organising and the zonal jet returning early next week to turn the flow westerly again, but still no signs of sustained re-organisation of the trop PV - it does appear that part of it will break away southeastwards into Northern Europe, while the bulk of the trop PV retreats over northern Canada - which opens up possibilities of high latitude height rises. Still plenty of promise longer term from the morning runs.

Edited November 7, 2017 by Nick F

[Met4Cast]

Am I missing something? The GFS ensembles for London are showing 850hPa temps dropping to -15? Clearly not going to happen but, am I looking at the wrong charts? This new Wetterzentrale design is horrible 

[karlos1983]

Holy mother of god 1070mb Greeni High  

 

come to pappa

That's good variation of the theme, Greeni high shows it's face again! Keep it comin 

[feb1991blizzard]

3 minutes ago, Daniel Smith said:

Am I missing something? The GFS ensembles for London are showing 850hPa temps dropping to -15? Clearly not going to happen but, am I looking at the wrong charts? This new Wetterzentrale design is horrible 

Wrong chart.

[johnholmes]

finally posting this where it should be!

Looking at the realistic future, say 6-10 days or so and the anomaly charts are inconsistent with one another and from day to day, so fence sitting as to the surface weather beyond say T+120 hours. Up to then one day milder and wetter one day colder and generally drier. Frost possible if ridges coincide with overnight periods. Even snow in showers for the Scottish hills, say above 1,000 ft and the highest peaks in N England. Beyond that and it looks, perhaps, the Atlantic may take over but I would rate it only 60% for that. Toss a coin comes to mind and I have no idea for the end of November let alone further out. Unless the Met O model seasonal output changes at the next issue (usually out soon after 10 th of the month) then I would feel little sign of any deep long lasting cold. Of course they could be wrong, so coldies can live in hope!

[carinthian]

22 hours ago, carinthian said:

The fine mesh model we use for snow prediction amounts for our location was 27cm for the 12 hour period to 9am this morning. This measurement taken outside the apartment was taken at I hour ago. Just amazing prediction within a forecast confine of 2 km sq. The measurement if you cannot see it is , guess what ..27cm!!

C

Morning all, ended with just over 30 cm of fresh snowfall. Forecast freezing level around 2000m mark for the rest of the week. A bit early for fine mesh model to give us a accurate top up next Sunday. But the portal models we have at our disposal show 14cm for next Sunday evening into Monday morning with freezing level dropping to 900m. Looks like a wave will across the Southern half of the British Isles on Saturday and affect the Alps during Sunday with much colder air tucking in on Sunday night to produce snowfall. Indications of a sub tropical air mass sector  wrapped up in this wave for a short time to affect Alpine Regions , possibly sourced via storm ,Rina will give the added complication of quick thaw before the polar air takes over. All very interesting and dare I say exciting.

[Summer Sun]

14 minutes ago, Daniel Smith said:

Am I missing something? The GFS ensembles for London are showing 850hPa temps dropping to -15? Clearly not going to happen but, am I looking at the wrong charts? This new Wetterzentrale design is horrible 

Wrong chart this is London

[Snowy L]

26 minutes ago, Daniel Smith said:

Am I missing something? The GFS ensembles for London are showing 850hPa temps dropping to -15? Clearly not going to happen but, am I looking at the wrong charts? This new Wetterzentrale design is horrible 

No you have the right chart. Thats London

Ontario.

Edited November 7, 2017 by Snowy L

[Jeremy Shockey]

High pressure of 1072 mb on the GFS 6Z around Greenland for Nov 19th could be interesting !

[tight isobar]

5 minutes ago, Jeremy Shockey said:

High pressure of 1072 mb on the GFS 6Z around Greenland for Nov 19th could be interesting !

...could be being the correct term.

On the 6z gfs its around' 300-500 miles too far east to have mass impact for our shores.

'However'...

Its been flagging up on occasion lately!

And given current northern hemispherical situ-state...everthing in regards to blocking-and evolution/evolutions is worth notice, mid/longer term.

[tight isobar]

Just now, tight isobar said:

...could be being the correct term.

On the 6z gfs its around' 300-500 miles too far east to have mass impact for our shores.

'However'...

Its been flagging up on occasion lately!

And given current northern hemispherical situ-state...everthing in regards to blocking-and evolution/evolutions is worth notice, mid/longer term.@1070 greeny.

 

[karlos1983]

AO looks pretty much nailed on to go negative.

 

Edited November 7, 2017 by karlos1983