Model Output Discussion 1st Nov.2013

[Jonan92]

 

Some disturbed vortex

[Summer Sun]

GFS starting to show a pressure rise around mid month now as per the 06z ensemble

 

 

 

 

[Mark Neal.]

ECM ends with a cooler NW flow, bit more amplification showing in the models, so not the mobile westerly flow we are seeing right now. Interesting to see what the ECM/GFS et al show in coming days with a more disturbed vortex and signs of a artic high which is certainly more interesting albeit right out in FI. 

[Summer Sun]

This evening's ECM is miles apart from its 00z ensemble run

 

12z

 

 

00z ensemble

 

 

the 12z ensemble will be interesting

Edited November 2, 2013 by Summer Sun

[Jonathan Lang]

A clear upwards trend in air pressure in the GEFS so perhaps a break in the rain in the foreseeable future but I'm not fully convinced as the scatter is quite large.

 

[IDO]

ECM ends with a cooler NW flow, bit more amplification showing in the models, so not the mobile westerly flow we are seeing right now. Interesting to see what the ECM/GFS et al show in coming days with a more disturbed vortex and signs of a artic high which is certainly more interesting albeit right out in FI.

I've given up on those ECM T240 charts. I am sure one day they will come to fruition but until the mean runs with that pressure rise, I will pass it by.The 0z ECM mean for T240: Not unlike the GFS T372 mean from the 12z: Where GFS in FI defaults to zonal. ECM (op) seems to pump out cliff-hanger pressure rises.The GEFS and ECM members appear to be split re any pressure rise in our vicinity, so although a possibility, it is one that the GFS op runs keeps pushing back; now at T312 but transient and pushing east by T384, bringing in an Atlantic trough to our west:T312: and by T384: Then seemingly back to square one; though any drier interlude is welcome. Edited November 2, 2013 by i'm dreaming of...

[bluearmy]

i wish i could see what is causing the interest in the polar profile. all i see is attempts to stick a ridge into the arctic being rebuffed by a strengthening p/v.  to say that eventually one of these will make it is surely hopecasting. we're just as likely to see the pattern of repeated ridging come to an end ??

[UV-RAY]

i wish i could see what is causing the interest in the polar profile. all i see is attempts to stick a ridge into the arctic being rebuffed by a strengthening p/v.  to say that eventually one of these will make it is surely hopecasting. we're just as likely to see the pattern of repeated ridging come to an end ??

But it was these attempts that brought us our cold spell in December 2010 ba.

[Frosty.]

Tonight's Ecm 12z op run brings a real T+240 hours tease .. T+264 would unleash an Arctic blast once that low to the northeast pushes into scandinavia, it's considerably better in terms of the chance of an early cold snap than we saw on the 00z this morning. As for the run overall, it's very unsettled and windy at times with gales and bouts of heavy rain alternating with sunshine and showers, the occasional weak ridge rushing east and the timing of those could mean we have a few early frosts before the next low pushes in off the atlantic, temperatures look rather depressed, around average or a bit lower across the north and only transient mild conditions across the south. There is a risk of snow showers or heavy snow at times across the highest hills and mountains in scotland with no mild incursions reaching that far north in the next 7-10 days.

[Newberryone]

From a cold lovers perspective I'm rather pleased with the latest Ecmwf op run in that it seems to be bringing more and more cold incursions in later frames as opposed to an almighty and everlasting Azores high which seemed quite likely in recent days.

I agree the jet stream does appear to be shifting slowly north in later output from many members but all in all I feel this might just be a forerunner to an already highly anticipated mid-month change.

 

I eagerly await Winter Wonderland scenes of this nature to be replicated the length and breath of both the British Isles and Eire over the coming months  

 

 

http://www.youtube.com/watch?v=6zU2Q-Yc5zg

 

[Cheshire Freeze]

But it was these attempts that brought us our cold spell in December 2010 ba.

 

Exactly, I'd rather have the attempts than not have them! That's for sure.

[Summer Sun]

ECM 12z ensemble similar to the 00z one

 

 

00z had the high a bit further north

 

 

 

Virtually no support for ECM at t240 anyway

 

[Cheshire Freeze]

ECM 12z ensemble similar to the 00z one

 

 

00z had the high a bit further north

 

 

 

Virtually no support for ECM at t240 anyway

 

 

Gavin I'm not entirely sure you know how to use ensemble mean charts....especially at 10 days out. You've been told repeatedly that the spreads at that range are far more useful.

 

You're not going to get an exact replica of the op at 10 days out as a mean chart.

Edited November 2, 2013 by CreweCold

[Summer Sun]

Latest from Gibby, the chances of a major pattern shift from the South rather than the colder North seems more likely.

 

All models show a very strong Westerly flow through the coming week with incessant Westerly winds delivering spells of rain and showers from fast moving troughs and Low pressure areas moving quickly East across the Atlantic and generally to the North of the UK. Gales will be frequent and severe in places exposed to the West at times and prolonged dry weather will be at a premium in any one place. Temperatures however, will be close to average despite feeling rather cold at times out and about and perhaps more generally for a time on Monday.

 

GFS then shows next week as unsettled and windy too with some heavy rain before colder conditions spread East behind a cold front. High pressure builds from the SW then with some fine and dry weather briefly for the South. However, improvements are quite muted tonight as Westerly winds return with further rain at times for the remainder of the run with average temperatures.

 

UKMO closes it's run next weekend with a bank of Low pressure to the North of the UK with a very broad and strong Westerly airflow bringing further troughs and accompanying spells of rain East across the UK interspersed by sunshine and squally showers. It would feel somewhat chilly though temperatures should remain close to average.

 

GEM shows a windy and unsettled period throughout it's output tonight. high pressure does move up over france later in the run but not close enough to the UK to maintain a strong WSW flow with troughs carrying rain East across the area on numerous occasions over the run.

 

NAVGEM too is little different tonight with gales frequent and severe in places with spells of rain alternating with squally showers and sunny intervals.

 

ECM keeps the Autumn flag well and truly flying at full speed as the bandwagon of Low pressure and attendant wind and rain rattles across the UK throughout the run with just a few drier and brighter intervals at times. 

 

The GFS Ensembles show a continued Atlantic based pattern with a strong and blustery Westerly flow throughout the two weeks with some rain at times but with some drier interludes too and temperatures overall averaging very close to or at times a little above average.

 

The Jet Stream is showing almost incessantly blowing across the Atlantic and over the UK through the period with the migration North again less evident tonight through Week 2.

 

In Summary the weather looks like staying wet and windy with spells of rain and showers for all areas at times in strong and blustery Westerly winds. Though there is less evidence again tonight of the rise of pressure from the South the chances of a major pattern shift from the South rather than the colder North seems more likely.

 

http://www.norton-ra...is(2859336).htm

Edited November 2, 2013 by Summer Sun

[bluearmy]

But it was these attempts that brought us our cold spell in December 2010 ba.

 

i'm not sure it was quite as straightforward as that SI.  to be effective, i think the ridges have to pump more s/n into the arctic than they are managing. currently we see them being flattened before they get going. that said, there was more wave 1 energy showing on this mornings berlin output.  want to see that become a trend before getting too interested. as for it being better to have them than not CC, of course thats the case but it would be a very odd hemispheric set up indeed that was flat zonal all the way around. 

[chionomaniac]

The route to cold this November will always be from a northwesterly airflow around the back of an Atlantic ridge and at last this is starting tp possibly show up on the extended anomaly charts.

 

Here is the November expected anomaly composite based on the closest anologue years. 

 

 

The GFS 11-16 day anomaly charts are starting to have a similar look about them - so confidence for an Atlantic ridge can grow tentatively for later in the month.

 

 

THere is a bit of a confusing signal between the MJO and GWO, but the one thing that I can see omnipresent this winter is already showing. That is the strong Pacific ridge.

[legritter]

Tonights charts and data ,i will certainly take it , plenty of action going on right out till the end of most runs ,then a fair shot at something colder perhaps on that distant horizon .perhaps some colder air heading in our direction towards mid month ,cant believe that this time last year wehad  2 ins of snow ,which was melted in minutes .

[Captain Shortwave]

Hmm have to wait and see about the ECM output, I expect that ridge will probably end up further west up the East coast of the State/Canada, rather than near us and producing a colder north/north westerly flow. Day 10 ECM output has had a habit of flip-flopping a lot

Hope isn't lost though, I still feel heights will rise from the south in about 10 days time, this has backing from the CFS and JMA, interestingly the heights want to start building more extensively through the UK and eventually towards Scandinavia. This video shows the output from the 2 nicely.

http://www.youtube.com/watch?v=-VXh5Bfm9AQ

 

Offers hope of potentially getting out of this pattern, for those who don't like lots of rain anyway. Potential for temperatures to turn cooler if the block does start to set up.

[Cloud 10]

Bit of a strange one the MJO at the moment which is in phase 1 which gives us this composite which isn't even close to the anomalies across the northern hemisphere at the moment,aside from the UK troughing.

 

 

 

 

FWIW the CFS ensemble chart for November very much with the Pacific ridge.

 

 

 

 

 

[forecaster]

Gavin I'm not entirely sure you know how to use ensemble mean charts....especially at 10 days out. You've been told repeatedly that the spreads at that range are far more useful.

 

You're not going to get an exact replica of the op at 10 days out as a mean chart.

 

I don't agree. Comparing the deterministic with the ensemble mean should be part of the approach.

 

See the (not-unquestionable) Bible here: http://www.ecmwf.int/products/forecasts/guide/user_guide.pdf

[Cheshire Freeze]

I don't agree. Comparing the deterministic with the ensemble mean should be part of the approach.

 

See the (not-unquestionable) Bible here: http://www.ecmwf.int/products/forecasts/guide/user_guide.pdf

 

We'll agree to disagree then. It's impossible to tell whether the op run has no support (as Gav put it) without seeing the spreads and the individual perturbations. Unless you have psychic abilities that is.

[Cloud 10]

A high spread around the UK at day 10 from the ECM ensemble mean.

 

[draztik]

The ensembles are continuing to show a trend towards a neutral/weak positive NAO this evening. So by mid month, we could see a pattern change away from the unsettled conditions of the last few weeks.

Conversely, the AO is not showing a similar decline. It continues with a fairly positive signal through its forecast period. (make of that what you will)

Edited November 2, 2013 by draztik

[Captain Shortwave]

The pub run like many recent GFS operationals is trying to get heights in towards the UK during week 2

 

A more neutral NAO with a positive AO would leave this as a pretty reasonable solution. Of course any heights near or over the UK will bring chilly conditions at this time of year with some frost and fog around.

[Frosty.]

I see signs of potential polar maritime incursions on the models today and even a chance of arctic air being drawn south if the highly rated ECM 12z verified..there would be a mid november cold snap, at least we are in with a chance. :- )