Model Output Discussion 01/09/17

[Cheshire Freeze]

22 minutes ago, Hocus Pocus said:

They’ve hardly covered themselves with glory over the years though, I’m not suggesting that they are wrong now but all long range modelling is pretty poor really. 

I've heard this one wheeled out before.

In reality the models (whichever you decide to look at) generally have a very good handle on situations which mirror long term climatology. With this in mind, when a model forecasts zonal, it's usually proven correct.

It's when it's the other way round the modelling tends to struggle. Seen many a time something 'juicy' has been shown, only to evaporate as the time nears.

[Geordiesnow]

11 minutes ago, CreweCold said:

I've heard this one wheeled out before.

In reality the models (whichever you decide to look at) generally have a very good handle on situations which mirror long term climatology. With this in mind, when a model forecasts zonal, it's usually proven correct.

It's when it's the other way round the modelling tends to struggle. Seen many a time something 'juicy' has been shown, only to evaporate as the time nears.

I think the issue is that we assume once the models show zonal, they don't change from run to run in the long term because they do but because we are not focusing every single run. Also the models may show zonal lasting a while but what tends to happen in the medium term, a new signal gets picked up and then something else is on the horizon, sometimes a set up that favours cold.

I don't think long term forecasting is too bad in general but its the details that just varies from run to run which produce different results, height rises over the poles is consistent but the strength and positioning keeps altering so how it may affect our weather remains to be seen. I havant seen too much evidence that any cold that may head our away will be all that potant but its something that can't be ruled out. What also can't be ruled out is that the blocking has very minimal affect on our weather on a cold perspective.

[jules216]

It comes to me as no surprise that models are churning out charts like this for November if you look at the last 30 years weak LA Nina reanalysis for November,-AO,-NAO, it then brings quite a zonal December,but both January and February blocked, good thing is that both solar and qbo are playing ball this winter,I am a little surprised that not enough weight and discussion is given to SST to our West as in USA the PDO is a major winter driver, if we struggle to achieve reasonable amplification from this potential considering that LA Nina and cool Novembers are good match,then my concern about unfavourable SST in N.Atlantic will increase

Edited November 11, 2017 by jules216
Typo

[NorthYorksWeather]

Large differences between GFS and UKMO at 144hrs.

[Daniel*]

As you can gather I’m not getting much sleep GFS 00z is looking a peach with a northerly flow swinging northeasterly, with renewed amplification of the ridge to west of British Isles retrogressing NW. Lack of cold air nonetheless overall synoptic evolution very promising for coldies. 

[knocker]

Regarding the weather today the UK can be divided into two sections. South of a line central Wales,south Midlands and towards the south east pulses of rain, sometime heavy, lasting most of the day as a slow moving front associated with the wave moves south, The wave is over Weston Super Mare by Sunday 00. Also quite breezy in the south west for a time. I can attest to that as currently moderate rain and very gusty here. Elsewhere much brighter but in Scotland a fair NW breeze with some squally wintry showers, of snow in the norther hills. Quite a temp contrast as well with much milder air south of the front. By Sunday the front has cleared and the wind has veered northerly over the whole of the UK so much cooler with wintry showers in Scotland and along the coasts.

By Sunday night the ridge has moved in leading to much calmer conditions and resulting in a widespread air frost Monday morning. The ridge is quickly brought under pressure by fronts and rain encroaching the north by late afternoon.

This battle between the high pressure and the energy emitted from the north west (although not exclusively) is the feature of the week which the former quickly loses and by Thursday 00 another developing low on a front has tracked north east and is 996mb just NW of Scotland bringing more rain and quite strong winds to the latter and N. Ireland. The low continues on it's merry way NE and the fronts and rain track south east across the UK on Thursday but at the same time another low has developed south west of Iceland and slipped into the general circulation and by Friday 00 is tracking east en route to Scotland.where it duly arrives Friday evening. So quite windy here, and N. Ireland, and quite possible some significant snowfalls, certainly on the high ground.

This is the signal for some renewed amplification with the Azores HP ridging north to the west and the trough plunging south all of which once again veers the surface wind northerly bringing wintry sowers to Scotland and the coasts  which is just about where wecame in so a good place to leave it. Humblest apologies for not mentioning winter but a double espresso is calling.

EDIT

The 8-13 GEFS anomaly is not adverse to this scenario

Edited November 11, 2017 by knocker

[knocker]

Although obviously varying in detail the ecm is pretty much along the same lines as the gfs

Edited November 11, 2017 by knocker

[northwestsnow]

Well looking at EC this morning we can safely say its below average all the way through really, here are the temp deviation plots-

a brief pause in the colder than average temps then back down she goes-

by day 10 there is some much warmer air being pumped up north towards Greenland.

All in all a cold and mainly dry EC

[northwestsnow]

And the 00z GEFS look to be generally below average apart from a small blip for a few days next week.

UKMO continues to look different at 144 so i guess we are non the wiser.

[That ECM]

low confidence in detail but higher confidence in general theme of a blocked pattern and interesting start to winter. The output is giving coldies hope and makes for good viewing which I guess we should enjoy as these may be the best/interesting output we see for the season!!

[NO LONGER POSTING]

Well with charts coming out like this... 

It's safe to say winter 2017-2018 is going a bit different to the last 3? 4? Keeping the faith.. Certainly beats the mild dank crap that we have endured for so many winters. Although last winter I did have a frost eartlier than this year and some very cold nights.

 

 

[mulzy]

The extended (11-15 day) eps definitely look better than last night's set with a stronger signal showing higher than normal heights to the north west and lower than normal heights to the east/south east.

Edited November 11, 2017 by Polar Maritime
Removed chart on request.

[northwestsnow]

5 minutes ago, mulzy said:

The extended (11-15 day) eps look definitely better than last night's set with a stronger signal showing higher than normal heights to the north west and lower than normal heights to the ease/south east.

Ext Eps are fickle beasts- personally i pay little attention to them.Nnot demeaning those that post them but id always treat them with a huge bucket of grit

And that goes both ways for me, whether they change for the better, or worse.

Edited November 11, 2017 by northwestsnow

[sebastiaan1973]

Latest EC plume De Bilt shows nothing special.

[Ravelin]

Let's play Spot the Difference with this mornings D8 GFS and ECM... 

 

Quite an impressive match at that range. But of course, now that they both agree that means both are likely to be wrong. 

[northwestsnow]

3 minutes ago, sebastiaan1973 said:

Latest EC plume De Bilt shows nothing special.

Yes, nothing out of the ordinary - no deep penetrating cold to tap into, i would suggest in a NW flow NW Britain is better placed for PM air then De Bilt.:)

[knocker]

Looking at the 10-15 GEFS and EPS anomalies this  morning and the general idea of the pattern (Atlantic ridge and trough) moving a tad east I'm wondering whether this is the precursor of the METO thinking and the Azores ridge eventually being parked in the vicinity of the UK initiating some cold and settled conditions. Just a thought as I have absolutely no idea what they are thinking and why.

[Rocheydub]

As long as UKMO are not singing from the same hymn sheet, confidence in this remains low. Need all 3 on board before we can start ordering rock salt!

[I remember Atlantic 252]

54 minutes ago, That ECM said:

low confidence in detail but higher confidence in general theme of a blocked pattern and interesting start to winter. The output is giving coldies hope and makes for good viewing which I guess we should enjoy as these may be the best/interesting output we see for the season!!

Flown by! cannot believe 5 years since your username!

Edited November 11, 2017 by I remember Atlantic 252

[Bristawl Si]

3 minutes ago, northwestsnow said:

Yes, nothing out of the ordinary - no deep penetrating cold to tap into, i would suggest in a NW flow NW Britain is better placed for PM air then De Bilt.:)

NW flow late November, with the North and its higher parts at risk of wintry showers.......isnt that bulk standard late Autumn weather for the UK?

[northwestsnow]

2 minutes ago, Bristle boy said:

NW flow late November, with the North and its higher parts at risk of wintry showers.......isnt that bulk standard late Autumn weather for the UK?

yes

[Polar Maritime]

16 minutes ago, Bristle boy said:

NW flow late November, with the North and its higher parts at risk of wintry showers.......isnt that bulk standard late Autumn weather for the UK?

Yes absolutely It's just been a few years since we have had even a standard Autumn!

Edited November 11, 2017 by Polar Maritime

[bluearmy]

34 minutes ago, mulzy said:

The extended (11-15 day) eps definitely look better than last night's set with a stronger signal showing higher than normal heights to the north west and lower than normal heights to the east/south east.

 

 

Unless someone with a license has tweeted that chart then you could get weather.us in a bit of bother by posting that  mulzy. 

Ukmo trying to play devils advocate but in general the direction of travel is one where the jet will likely undercut mid Atlantic ridges and feed into a euro torugh. Almost the holy grail of winter patterns - however in November (and certainly next couple weeks), drawing in cold enough undercutting air to produce snowfall will be a struggle. the trend is to push the ridging further east to cover the uk and given the propensity for the nwp to overstate European low heights, I'm beginning to lose my mojo on this particular phase of potential wintry conditions. 

Edited November 11, 2017 by bluearmy

[Summer Sun]

UKMO extended (right) isn't a great deal different from t144 (left)

[Ice Day]

Improving set of overnight runs, remaining cold throughout the next 7-10 days which ties in with the Met updates.  Nothing notable for lowland areas YET. But cold is building to our east / north east, so if the pieces do fall into place we're in business and have some proper cold to tap into. Tremendous model watching at the moment, as Alan Partridge would say 'ten on ten'!