Model Output Discussion 18z 30/09/15

[knocker]

After a glance at the GFS 18z I would be forced to call it the undercut run as lows tend to stall to the SW

Charts courtesy weatherbell

Edited October 23, 2015 by knocker

[Cloud 10]

Very quiet today?

 

 

So after a couple of days of swinging toward faster flatter today they are moderating back the other way. So given that I think it is likely ECM will be much more amplified this evening and the models haven't quite yet resolved the pattern, at least not so far as the weather we can expect for our small island from day 5+

 

 

 

No better model to provide some extra amplification when needed.

 

Some stunning NH charts this evening so far,especially from the normally conservative UKMO,with the PV looking rather distressed.

 

[Jonan92]

In the FI of the GFS we can find a quite strange hemisferical pattern for November

 

[nick sussex]

No better model to provide some extra amplification when needed.

 

Some stunning NH charts this evening so far,especially from the normally conservative UKMO,with the PV looking rather distressed.

 

UN144-21.GIF

Yes the UKMO is the pick of the bunch so far in terms of interest. It won't develop that secondary feature running north which phases with the deep low exiting the ne seaboard of the USA. In terms of the upstream pattern NCEP weren't impressed by any of the operational runs today and went with the ensemble means. They are expecting an amplifying wave to work through the Midwest which could impact that trough.

[knocker]

Well it certainly looks like a trough will form in the lee of the mountains thanks to Patricia which will travel NE bringing a deluge to Texas and eventually linking to  the upper trough bringing cold air down from the Arctic to the NE.

[Cloud 10]

Yes the UKMO is the pick of the bunch so far in terms of interest. It won't develop that secondary feature running north which phases with the deep low exiting the ne seaboard of the USA. In terms of the upstream pattern NCEP weren't impressed by any of the operational runs today and went with the ensemble means. They are expecting an amplifying wave to work through the Midwest which could impact that trough.

 

12z gfs ens.mean at day 6 is known technically as the "horse and rider"configuration.

 

[MR EXTREMES]

So it looks like my Azores high pressure being push back further sw has happened allowing the chance of an undercut

[Mucka]

ECM tonight sending all the energy over the top of the block after 120h which the  likes of GFS and JMA disagree with, up to 120h it is actually more amplified but then very fast upstream with the jet riding over the top.

It has been very erratic of late though o hard to know what to make of it.

[nick sussex]

The ECM now performs another change with a strong high over Europe. The GFS has high pressure but with a different view of the Arctic and profile over Greenland.

 

Odds this evening have shortened on the Atlantic making very little inroads and high pressure holding firm. The ECM at day ten moves the PV towards Siberia and has a favourable set up for a certain synoptic ! if the upstream pattern amplifies but given the ECM performance over the last week I'd be shocked if this remains the case by tomorrow.

 

Theres still some uncertainty with how far north the high gets and how much if any trough disruption happens so I'd expect to see more changes in the coming days.

[knocker]

The GEFS 6-10 anomaly reinforces the Scandinavian HP with the trough orientated Greenland to Spain. NOAA for the same time frame is not adverse to the idea although it's not quite as bold with the trough. Thus the stream lines will be in the southerly quadrant but the detail remains as to what airmass will prevail but some fascinating evolution in prospect with a late WAA burst for the dafs a distinct possibilty.

 

In the later 11-15 time frame the GEFS relaxes the HP and nudges it east and also lessens the prominence of the trough which veers the flow and brings the UK under the influence of the Atlantic low pressure. Again NOAA has no great argument with this scenario.

 

But as the NOAA discussion points out low confidence DUE TO LARGE DIFFERENCES BETWEEN THE DETERMINISTIC GFS AND ECMWF SOLUTIONS  in the 6--10 and TO MODEL SHORTWAVE TIMING DIFFERENCES ASSOCIATED WITH A PREDICTED LOW AMPLITUDE PATTERN OVER MUCH OF THE FORECAST DOMAIN in the 8-14.

 

In other words tune back in tomorrow.

 

http://www.tropicaltidbits.com/

Edited October 23, 2015 by knocker

[Mucka]

Those 11-15 day anomalies from NOA and GFS look pretty close to me knocker, GFS doesn't show UK under Atlantic influence as such, rather it shows a battleground scenario pretty much over the UK as does the NOA IMO.

Edited October 23, 2015 by Mucka

[ANYWEATHER]

Hi Everyone! This is a question , but does the massive Hurricane Patricia thousands of miles away from the Uk, have such dramatic effects on the models tonight? I really think so....Perhaps Im wrong and stand corrected! But tonights models output  does seem strange to me , much to much blocking east of the Uk...Really does not look right! I think we can write off the predictions from the models in the next couple of days Lets see the demise of this Hurricane in the next 24hrs and see what tomorrows models show?

[Summer Sun]

High pressure dominates the very end of October and early November on tonights ECM

 

 

Although the 850's look fairly mild I think it could get quite chilly at the surface

Edited October 23, 2015 by Summer Sun

[Costa Del Fal]

Hi Everyone! This is a question , but does the massive Hurricane Patricia thousands of miles away from the Uk, have such dramatic effects on the models tonight? I really think so....Perhaps Im wrong and stand corrected! But tonights models output does seem strange to me , much to much blocking east of the Uk...Really does not look right! I think we can write off the predictions from the models in the next couple of days Lets see the demise of this Hurricane in the next 24hrs and see what tomorrows models show?

Ahh but are we dismissing it because you don't like what you see? We have all been guilty of this on the past and things have flopped a fair bit recently but the last 2 months ish have seen large amounts of blocking to our east and tonight's ECM sees a high pressure looking similar to what we had a month ago at least in Western Europe with a low towards the Azores. Not implausible. Seems silly to all of a sudden to write off the next 2 days outputs. Would You be saying the same if a colder more unsettled synoptic was showing?

Hmmm.....

Edited October 23, 2015 by Costa Del Fal

[Summer Sun]

ECM ens supporting the idea of that blocking high to our east, continuing into November possibly moving a bit further west towards the UK

 

[knocker]

Those 11-15 day anomalies from NOA and GFS look pretty close to me knocker, GFS doesn't show UK under Atlantic influence as such, rather it shows a battleground scenario pretty much over the UK as does the NOA IMO.

 

I thought that's what I was saying although I'm not totally sure what, "under Atlantic influence as such" means.

 

 

In the later 11-15 time frame the GEFS relaxes the HP and nudges it east and also lessens the prominence of the trough which veers the flow and brings the UK under the influence of the Atlantic low pressure. Again NOAA has no great argument with this scenario.

 

I said under the influence of the Atlantic low pressure as the airflow has veered mainly westerly. That is not to say it's a dominant influence and certainly still all to play for as I later mentioned.

Edited October 23, 2015 by knocker

[knocker]

The ECM anomaly for T240 is in no doubt with the HP in charge, rather fits with the ops run, with a weak cut off upper low over Spain. This relaxes in the ext period with the HP moving east and a more zonal flow taking over.

Edited October 23, 2015 by knocker

[johnholmes]

I made these notes earlier after looking at the NOAA 6-10 day chart

 

noaanoaa

on FRI and the 6-10 has reverted back to the idea of ridging/building anomaly heights fairly close to the uk, see below

 

notes from Wed below

Noaa 6-10 much as one above but slight increase in +ve heights over uk with slightest indication of ridging e of Iceland towards Greenland; this is increased in both on 8-14

Also on both trough is w of last prediction

Missed Thur

link

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

Not too sure as it is quite a change over 48 hours but it is supported by the 8-14 chart.

As to what effect the very large Hurricane almost on to Mexico will have, who knows, we have to wait for 2-3 days to see how the anomaly charts behave let alone the synoptic models.

[Scorcher]

High pressure dominates the very end of October and early November on tonights ECM

 

 

Although the 850's look fairly mild I think it could get quite chilly at the surface

 

That is a dream summer run, and next week is looking very mild- perhaps not dissimilar from the end of October last year. With a continental SE flow we could see the high teens quite widely as we go into midweek. I imagine many of us will see some sunshine as well, as is often the case with a warm flow off the continent.

[Mark Parsons]

That is a dream summer run, and next week is looking very mild- perhaps not dissimilar from the end of October last year. With a continental SE flow we could see the high teens quite widely as we go into midweek. I imagine many of us will see some sunshine as well, as is often the case with a warm flow off the continent.

A sign of things to come maybe? High pressure to our east in most forms once into winter will herald cold conditions, this looks to be the form horse for the start of winter, anticyclonic brought on by el nino?

[Singularity]

That 12z ECM det. run is bonkers in its own way - the phasing of a compact, intense low NW of the UK with a large, very deep low exiting Canada at +192 hours results in a supercharged westerly push that transports a wedge of relatively warm air from the far-western N. Atlantic to NW Russia in the space of 48 hours!

 

Sure, it creates a very deep low over Siberia, but what a way to do it! In the meantime, trough disruption west of the UK at +168 hours proves well aligned to bring us some exceptionally warm air at the 850hPa level during the following few days. GFS's 12z det. was similar, though not quite as impressive (and the 18z is less still as the LP is closer to our shores), and that model came up with some high teens maximums at times. Still a way to go to beat Halloween of 2014 though, which saw low 20's widely across the far south.

 

 

Oh and it was nice of the GFS 12z det. to show us what's achievable in terms of the Arctic profile should the Atlantic prove unable to overrun the blocking high over Scandinavia at any point in the next fortnight. Should the storm escaping north following the trough disruption in about a week's time dissipate fast enough, such an outcome is achievable, as the low off Canada doesn't have much to phase with, meaning the jet stream doesn't get to extend eastward much at all. Such a huge contrast to the ECM 12z det. run's outcome - the mind boggles!

[bluearmy]

Certainly a more Interesting October model watching than I recall for a few years

[knocker]

Yes some fascinating stuff.

Last night's 18z GEFS upgrade has the negative tilted trough to the west down as far as Coruna which drags warm air up from the south with the block to the NE. The southerly tends to veer south westerly as the trough dissipates and is replaced by another trough situated further west.

 

This morning's ops run follows this script for a while and then replaces the block with a broad swathe of low pressure stretching from the Atlantic through Scandinavia.

Chart weatherbell

Edited October 24, 2015 by knocker

[Turnedoutniceagain]

An early 'Beast' ?? 

[Captain Shortwave]

This mornings ECM is a little better if you want very mild/warm conditions as we end October, less of a UK/Scandi mid latitude block and more of a Euro/Scand high which gives us a south to south easterly feed across the UK.

 

Though the west would see some rain at times as fronts try to push eastwards without much success.

WHilst there is a lot of interest in the general northern hemisphere view, it is worth noting that the pattern, at least in the European area is fairly similar to last year.

Last Halloween

Mid November

 

So again the models showing a lot of blocking to our east, similar to last year. Whilst interesting we do have to make an note that a lot can change as we move through into November and that things can change for better or for worse.

 

As for the other models this morning, they show a more successful push eastwards of the Atlantic, though it does take a few attempts to flatten the block to our east off to allow the jet to pass through northern Europe.

Edited October 24, 2015 by Captain shortwave