Model Output Discussion 01/09/17

[Day 10]

The 'big' 3 for comparison:

Clear as mud!

[A.J]

1st rule of weather forecasting......look at what the model suites show in FI and expect the opposite outcome, generally more right than wrong, and not get hung up on mild/charts way off in the future nor indeed on each and every model run as the smallest change in the initial data entered in the supercomputers causes huge changes further on....it's called FI for a reason, possible trends and nothing more..........Still, there's nothing quite like the thrill of the chase....lol

[knocker]

According to this evening's ecm there must be a chance of some snow to the NE of the front on Monday, certainly on the higher ground. At 12 it is lying Carlisle to the Humber.

Edited November 16, 2017 by knocker

[nick sussex]

Painful!

So close but the pattern needs to go further se. If you can just get the shortwave at T144hrs further se then it could make a huge difference.

There could be some huge differences north/south. Northern Scotland in a slack cold ne flow could see very low night time temps and still a chance of snow there.

So many variables at play, just enough time to see some improvements but equally it could go completely pearshaped.

[Gowon]

A lot of snow for Scottish highlands with this chart I'd imagine..

[Frosty.]

5 minutes ago, joggs said:

Can't they just all agree and put it to bed:0

Where's the fun in that..fascinating model output with potential for drama /excitement like last night's 18z at any time in the days / weeks ahead..and it's not even winter for another two weeks!

[nick sussex]

These are two very important features at T120hrs.

Its essentially a race between the shortwave circled red and that colder air heading sw which as soon as it hits energizes the shortwave, as soon as that happens you get a ne motion track developing as it deepens rapidly.

We need to see that round shortwave to disrupt and send energy se. In these cases you can tell how much of a fight its putting up. The football shape its fighting, rugby ball its beginning to lose the fight, once that shortwave energy elongates its a goner.

Those blues you see near Iceland and their track is crucial we don't want this sw track we want that more south so it engages any energy further to the east and south.

Edited November 16, 2017 by nick sussex

[blizzard81]

Another mid term tease, this time from the ecm. Ok for northern Scotland. For the rest of us - next run please. 

[Gowon]

3 minutes ago, nick sussex said:

These are two very important features at T120hrs.

Its essentially a race between the shortwave circled red and that colder air heading sw which as soon as it hits energizes the shortwave, as soon as that happens you get a ne motion track developing as it deepens rapidly.

We need to see that round shortwave to disrupt and send energy se. In these cases you can tell how much of a fight its putting up. The football shape its fighting, rugby ball its beginning to lose the fight; once that shortwave energy elongates its a goner.

Those blues you see near Iceland and their track is crucial we don't want this sw track we want that more south so it engages any energy further to the east and south.

Hopefully the two lows north and south of the Azores will merge and drag some waa which should help sustain the blocking?

[Frosty.]

Just now, blizzard81 said:

Another mid term tease, this time from the ecm. Ok for northern Scotland. For the rest of us - next run please. 

Baby steps

Plenty more model drama to come and great post from nick sussex as usual

[blizzard81]

Let's see what the ecm ensembles bring. 

Edited November 16, 2017 by blizzard81

[booferking]

And the engaging of energy what @nick sussex talking about has a nice trend over the last 3 runs everything is moving South East. 

Edited November 16, 2017 by booferking

[phil nw.]

Tantalisingly close to nationwide cold at T120hrs

That mid-Atlantic trough cutting a bit further south than previous ECM runs.Maybe a little bit of mileage left in this.

 

[nick sussex]

1 minute ago, D.V.R said:

Hopefully the two lows north and south of the Azores will merge and drag some waa which should help sustain the blocking?

Originally those better GFS outputs tried to absorb shortwave energy into the main low.

With this type of set up we need a trigger shortwave to run into France and drop heights there, this drama is overall being caused by the block too far west which leaves the main attack point for low pressure similarly too far west.

The further se the main core heights of the block are the better chance for something interesting.

Both the ECM and UKMO have made some improvements in the earlier timeframe, the GFS has jumped ship but I'd rather see the Euros improving than the GFS going it alone with its better outputs.

Its still looking a bit close but no cigar for the UK as a whole but just about enough time to see some changes but its a race against time now!

Cue one of my melodramatic film analogies! I'll think of one for later! lol

 

[Frosty.]

I really think this Ecm run has a chance because earlier, Exeter said the north will be cold next week and potentially, the way I see it, further south could become colder too..dramatic stuff from the models..hope we coldies get some well deserved luck!

Edited November 16, 2017 by Frosty.

[Northern Sky]

55 minutes ago, Catacol said:

Accurate I think. Modelling of the jet over the Pacific has been all over the place too recently, and this has helped create huge model uncertainty, but what we can see clearly is low AAM, no MJO influence yet (probably 4 more weeks away), a Nina pattern taking hold (uncertainty on how long it will take to couple effectively to the atmosphere) and the vortex predictably gaining strength. The decoupled state of ocean, atmosphere and vortex at present will allow variations from a Nw and Sw direction with a jet that will look anything but flat for a bit longer yet, but without proper Pacific forcing the chance of a substantial block to our north setting up shop is slight. We may get temporary topplers, and I suspect a good start to the Scottish ski season my be in the offing with plenty of NW shots - but lowland snow via sustained cold in the south just doesn’t look likely to me.

From here the odds are in favour of a move to a more zonal December. This may be delayed by a week if the trop pattern can stay disconnected a while longer - Ant Masiello has suggested this is possible - but westerlies by mid December are probable.

Patience is required. The chance of a change to something much more interesting sits with the next MJO cycle (possibly aided by a resistance to Nina anomalies in the central Pacific) and hopefully a Nina that doesn’t bottom out too low and perhaps begins to wane in January. This could create interest via vortex disruption and renewed pulses of energy into northern latitudes that could possibly aid in creating a blocking pattern.

This is a January conversation. Right now I’m happy with a few frosts and a fairly benign pattern with westerlies slow to take hold. But I think it is only a matter of time until they do.

Anyone heard from GP recently?

Interesting post Catacol. Not what I was hoping for - my favourite time for cold is December - but given the consistent output from the long range models and the background signals being what they are, it does seem the most likely outcome. I always enjoy reading your reasoned and balanced posts but I really hope you, the models and the background signals are wrong.

[Frosty.]

Remember just 24 hours ago the Ecm 12z was a nationwide damp squib mild mush fest, plenty of cold potential tonight, especially further north with more twists to come i'm sure!

Edited November 16, 2017 by Frosty.

[Summer Sun]

The ECM ens shows the Op is slightly milder than the mean from mid next week onwards

[BLAST FROM THE PAST]

FFR.......Far From Resolved.  This is going to the wire......I hold on to my ‘hopes’ as still on the table

 

BFTP 

[nick sussex]

6 minutes ago, Summer Sun said:

The ECM ens shows the Op is slightly milder than the mean from mid next week onwards

That's a bit disappointing re 850 values. No appetite to really drive much colder air further south. Its a shame we don't have them for more northern parts of the UK, it could be theres a big split given the set up. I think the issue for the ensembles is the resolution drop given we're dealing with crucial shortwave track which normally is better handled by the higher resolution ops. If we were talking about a stronger block further east it might not be such an issue.

 

[Summer Sun]

2 minutes ago, nick sussex said:

That's a bit disappointing re 850 values. No appetite to really drive much colder air further south. Its a shame we don't have them for more northern parts of the UK, it could be theres a big split given the set up. I think the issue for the ensembles is the resolution drop given we're dealing with crucial shortwave track which normally is better handled by the higher resolution ops. If we were talking about a stronger block further east it might not be such an issue.

 

ECM ens is available widely here http://www.meteociel.fr/modeles/ecmwfens.php?carte=1 just click the map for the area and it will load up

Central belt of Scotland

Edited November 16, 2017 by Summer Sun

[That ECM]

10 minutes ago, Summer Sun said:

ECM ens is available widely here http://www.meteociel.fr/modeles/ecmwfens.php?carte=1 just click the map for the area and it will load up

Central belt of Scotland

Bournemouth  joking apart, nice link Summer Sun.

[Man With Beard]

Just flicking through the EC ensembles on weather.us, now out to about T82 and it's already complete carnage over that shortwave. The ensembles are clueless. We have pressure readings for NW Scotland anywhere from 996mb up to 1028mb  - and there is no obvious common position between the two.

[nick sussex]

Looking at the ECM ensembles for northern Scotland theres close to a 9 deg spread at day 5 indicating just how crucial the initial shortwave track is.

If you look at the ECM 850 spreads its quite unusual to see this type of spread at just T96 and T120hrs, you can see on both sides of the lighter shading running through the UK you have much less spread so its very finely balanced for those in the higher chance area for something wintry.

 

 

 

[Frosty.]

17 minutes ago, Man With Beard said:

Just flicking through the EC ensembles on weather.us, now out to about T82 and it's already complete carnage over that shortwave. The ensembles are clueless. We have pressure readings for NW Scotland anywhere from 996mb up to 1028mb  - and there is no obvious common position between the two.

One good thing about that, if it's as clear as mud it means coldies still have a fighting chance of seeing something wintry..ever the optimist me!