Model output discussion - late November

[Mapantz]

 

8 minutes ago, Mike Poole said:

in fact even Netweather has just underlined it with a red squiggly as I type...

That's your browser's spellchecker.

Edited November 23, 2019 by Mapantz

[northwestsnow]

Hum..

Not much to be said for the E C mean this evening...:(

[Jordan S]

Just now, northwestsnow said:

Hum..

Not much to be said for the E C mean this evening...:(

There's always tomorrow.  The E C mean will probably look somewhat different as has been the case in recent day's. 

[I remember Atlantic 252]

16 minutes ago, Mike Poole said:

My take is it means flow zonal to a particular latitude, give or take.  As opposed to meridional flow  with a big up and down component.  My favourite recent period of zonal flow was March 2018, all the way from Russia (yes it can be easterly as well as westerly, it just doesn't happen very often).

And I am as convinced as ever that zonality is not a word - in fact even Netweather has just underlined it with a red squiggly as I type...

Anyway the models are hardly showing zonal flow in either direction on the 12z runs in the reliable,  

used on here okay but, zonality and zoneality invalid in  Collins scrabble dictionary

Edited November 23, 2019 by I remember Atlantic 252

[northwestsnow]

Just now, jordan smith said:

There's always tomorrow.  The E C mean will probably look somewhat different as has been the case in recent day's. 

Perhaps...

The issue is we are not seeing the EC mean move away from the collapsing high scenario, its getting closer so confidence of it happening is increasing..

[knocker]

There are some significant differences between the ext mean EPS and the GEFs which indicates caution when considering the medium term evolution

Although the vortex is more or less in the same position the configuration is not the same because the EPS has no Alaskan ridge and thus a flatter flow across north America Not a huge difference downstream, perhaps the subtropical high not quite so influential, as the European trough takes closer order

NOAA favoring the GEFS

 

 

[Weather-history]

ECM 12z op and mean , 240hrs ago for midday today 

And the midday chart for today

 

GFS 12z op, 240 hrs ago for today

[Jordan S]

10 minutes ago, northwestsnow said:

Perhaps...

The issue is we are not seeing the EC mean move away from the collapsing high scenario, its getting closer so confidence of it happening is increasing..

Yeah as you saw on my previous post taking the Gfs Ecm and Gem output and blending them together it shows the high collapsing to a more traditional place for the UK just to the south and southwest with much milder Westerlies although as its still a week or so away can't be too confident yet although a little colder for a short time at the end of next week looking likely atm. 

Edited November 23, 2019 by jordan smith

[LRD]

4 minutes ago, jordan smith said:

Yeah as you saw on my previous post taking the Gfs Ecm and Gem output and blending them together it shows the high collapsing to a more traditional place for the UK just to the south and southwest with much milder Westerlies although as its still a week or so away can't be too confident yet although a little colder for a time atleast at the end of next week. 

I think the models have picked up on something that is more, er, traditional for these isles but it may be bringing it forward a bit early. As per the Met Office outlook. No big freeze on the cards either way but cold for a time before normality kicks in. Still watching what those pressure readings over Greenland do in early December though

As an aside, we never seem to get a big fat high over the country in autumn/winter anymore giving us stagnant conditions with pea-souper (freezing) fogs with some sharp frosts

[mb018538]

13 minutes ago, knocker said:

There are some significant differences between the ext mean EPS and the GEFs which indicates caution when considering the medium term evolution

Although the vortex is more or less in the same position the configuration is not the same because the EPS has no Alaskan ridge and thus a flatter flow across north America Not a huge difference downstream, perhaps the subtropical high not quite so influential, as the European trough takes closer order

NOAA favoring the GEFS

 

 

Looks most like to me @knocker. There has been a definite trend to lower polar heights and a stronger TPV the last day or so. AO plots nearly all positive now.

[knocker]

5 minutes ago, mb018538 said:

Looks most like to me @knocker. There has been a definite trend to lower polar heights and a stronger TPV the last day or so. AO plots nearly all positive now.

Sorry not quite following that comment

[LRD]

4 minutes ago, mb018538 said:

Looks most like to me @knocker. There has been a definite trend to lower polar heights and a stronger TPV the last day or so. AO plots nearly all positive now.

I keep reading/hearing how those NOAA charts are solid and less prone to flip-flopping. I'm sure it was only 24 hours ago that a huge red blob was centred over Greenland on that model. Now it's over the Bay of Biscay. As prone to rapid changes of heart as any model I guess

I might be being a little unfair as the atmosphere does seem to be in an unpredictable state at the moment

[Mike Poole]

Just catching up on the models properly today, after a short break, and as a gambling man, I'm confronted with a dilemma as to which horse to back:
To take the current trop model output first, there's quite a lot of uncertainty, even at T144, with in terms of amplification probably goes a bit like this ICON, GEM, ECM, UKMO, GFS:

Where we go from here is not certain, and obviously there are suggestions from the models going forward, but I don't think we know...
Meanwhile in the strat, there is a strange standoff between the GFS (now FV3 of course) and the GEFS ensemble members, with the GFS op not wanting to go with the SSW idea at all.  The GEFS 0z had all sorts of options at T384:

P8 has a split vortex SSW, first I've seen so far this year.  Others also have SSW wind reversals, GFS unmoved.  I also wanted to include this from the GEFS  12z

I note some posters on here yearn for cold, not all, but some (!).  And so back to the gamblers dilemma, which route does one back for cold?  The nascent heights in Greenland continuing to build further after the current push suggested by the op runs, in which case you might not want the strat to interfere?  Or a SSW reshuffling the deck and landing good for UK cold, but a few weeks down the line?  Or the seasonal model preferred result somehow coming between both to scupper it?   I think it will be one of the first two but at this point I'm not sure which of the two Is the better bet...

 

 

Edited November 23, 2019 by Mike Poole

[knocker]

2 minutes ago, LRD said:

I keep reading/hearing how those NOAA charts are solid and less prone to flip-flopping. I'm sure it was only 24 hours ago that a huge red blob was centred over Greenland on that model. Now it's over the Bay of Biscay. As prone to rapid changes of heart as any model I guess

I might be being a little unfair as the atmosphere does seem to be in an unpredictable state at the moment

Well it does appear that a major pattern change is underway so the upper air charts will change. But they are not as prone to flip-flopping

[bluearmy]

4 minutes ago, LRD said:

I keep reading/hearing how those NOAA charts are solid and less prone to flip-flopping. I'm sure it was only 24 hours ago that a huge red blob was centred over Greenland on that model. Now it's over the Bay of Biscay. As prone to rapid changes of heart as any model I guess

I might be being a little unfair as the atmosphere does seem to be in an unpredictable state at the moment

I guess it depends when the high anomoly was progged - as a mean across a week, if the high anomoly was showing for day 8-11 and that is now 5-8 then it will have dropped out 

fwiw, I still wouldn’t take too much from the current output post T144 

[carinthian]

5 hours ago, carinthian said:

Sorry a bit late with an up-date from the team as suggested in the above post sent earlier. Managed to have a discussion with specifics regarding the British Isles. They still in the thinking that a low will move close to Southern England next weekend before heading towards the Alps. Still a bit far out for their snow model predictions but indications that rain could turn to snow especially on the mountains of S. Wales and some other parts of Central Southern England later as the milder is under cut from much colder air mass established further north. Still a lot more runs needed but still showing also the low could easily move further south. Longer term, a switch to milder westerlies could be limited to the NW of Britain as their own model in now showing a resurgence of the Russian high again in its later span. What that leads to , not sure but could be back to square one ! Hope this helps.

C

With reference to the above post the UKMO extended chart to 168t looks to be in agreement with GEM model at the same time set and that's for next weekends low to slide over or to the South of England followed by colder air replacement. Still some time away  for changes as the low could even go further south as suggested by our team over here earlier today. The UKMO extended also shows more acute Atlantic ridging , similar to the GEM.  Think there could be some interesting charts in the morning runs. There appear to be variability with all models in the medium time span.

C

Edited November 23, 2019 by carinthian

[LRD]

7 minutes ago, bluearmy said:

I guess it depends when the high anomoly was progged - as a mean across a week, if the high anomoly was showing for day 8-11 and that is now 5-8 then it will have dropped out 

fwiw, I still wouldn’t take too much from the current output post T144. It not being nailed on makes it all the more interesting 

Fair point

And, agreed, forecasting beyond 144hrs appears to be especially tricky at the moment. But that makes model-watching all the more interesting

Edited November 23, 2019 by LRD

[BLAST FROM THE PAST]

1 hour ago, Ed Stone said:

I've always assumed the word 'zonal' to imply a broadscale pattern (LP near Iceland, HP near The Azores, broad swathe of generally westerly winds in between) Fred...But, if an entrained blob of -6C T850s requires a name-change, it's fine by me...

All the text-books I've read were in black-and-white!

Maybe so....but it implies 18000 mile SW’lies

BFTP

[Mike Poole]

Stronger heights into Greenland on ICON 18z, slight surprise as the 12z was considered an outlier, here T90 vs T96 on the last run:

[damianslaw]

Hard for many to do, but try sticking to placing pause/hold on model output at 144 hrs - saves much frustration and gnashing of teeth, anything beyond you always no matter what have to take with large margin for error. With this is mind, the models continue to show an evolution to something colder to end the month after a few milder wet days.

 

[SouthLondonCold]

Unfortunately the 18z Icon doesn't look quite so good at 120 hours compared to the amazing 12z run. This is solely because everything looks to be shifted a bit Eastwards with a stronger Newfoundland low, and less of a ridge towards Greenland ahead of the low, which is obviously not what we want.

[Mike Poole]

2 minutes ago, SouthLondonCold said:

Unfortunately the 18z Icon doesn't look quite so good at 120 hours compared to the amazing 12z run. This is solely because everything looks to be shifted a bit Eastwards with a stronger Newfoundland low, and less of a ridge towards Greenland ahead of the low, which is obviously not what we want.

Agree with most of that, but the comparison should be with the 12z T126 not the T123?

I think everyone agreed that the 12z ICON was at the extreme end of what could be achieved, so not to see a significant downgrade over this short T120 run is a good thing, now on to the pub run...

[SouthLondonCold]

Yes, not very intelligent of me, so many model runs I lose track of time! The good thing is that it shows tiny differences in the position of lows can affect the outcome a lot, and it is all a week away so still lots of time for the positioning to change slightly, and we are easily back in the game!

2 minutes ago, Mike Poole said:

Agree with most of that, but the comparison should be with the 12z T126 not the T123?

I think everyone agreed that the 12z ICON was at the extreme end of what could be achieved, so not to see a significant downgrade over this short T120 run is a good thing, now on to the pub run...

 

[Mike Poole]

GFS 18z at T168

More amplified than the 12z, T174:

And that ball low, the one that might provide significant WAA into Greenland?  GFS is never good with these, so more runs needed, but this is a good position, as it becomes closer to T0 I can see some improvements in the pipeline...we will see.

[ALL ABOARD]

 

Better chart from the 18z with regards to the WAA. 

All academic at this range tho as that low that cause the high to collapse may be a lot shallower(or not)