Model Output Discussion - 31/8/14 Onwards.

[knocker]

Indications to night that the anomalies have a slackening of the heights to the east and a shallow trough developing in the eastern Atlantic although still retaining ridging in the west. This facilitates developing a slack low pressure area around the UK bringing unsettled weather although with HP still around in mid and west Atlantic and a relatively weak jet nothing one would call dynamic.

Edited September 26, 2014 by knocker

[skifreak]

Should I organise an Inverness pre-season BBQ for Friday 3rd October on the basis of the latest GFS offering…

[Polar Maritime]

Again the GFS shows the Atlantic making inroads from around the 5th.

 

Edited September 26, 2014 by Polar Maritime

[Polar Maritime]

Again more unsettled charts showing this morning by the GFS out in the run, A very unsettled/cool if not cold N/W pm flow showing. Autumn proper could well be arriving.

 

[IDO]

Again the GFS shows the Atlantic making inroads from around the 5th.

 

 

 

Not really seeing the Atlantic this morning. The GEM has a short wave trough crossing west to east around D10 with Atlantic HP soon moving back in:

 

 Even with HP dominating these temporary troughs are to be expected.

 

GFS op has HP in charge for most till D9-10:  But the LP does not arrive till T300: 

 

That does not look like heralding a zonal wash out pattern change as GFS follows with a N/S split. However the GFS control keeps most dry for the whole 16 day run and at D13:

 

 D16: 

 

Looking at the upper temps both the op and control, especially the former look close to outliers with the mean in FI >5c higher and some members double that:

 

 

So this morning's GFS op in FI was a worse case scenario and unlikely. The T300 charts for individual members show very little sign of the Atlantic charging in. Really more of the same, HP close by with a slack setup. As we know with that scenario surface conditions may be difficult to pin down till much closet to T0:

 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=300.

 

Again CFS for October not really going with an Atlantic dominated UK: 

 

There have been predictions for the Atlantic to return from mid-September but it hasn't and there is no clear sign from any LR model it is due back in the next few weeks. That may change in future runs but at the moment a continuation of a more settled long wave pattern. Plenty of time for the Atlantic in DJF

[Frosty.]

The GFS 00z op run shows a very Anticyclonic early october but we lose the warmth, temperatures return to average and chilly nights with widespread ground frost & slight air frost with fog patches which may be slow to clear in places. Early next week shows a less settled blip with a risk of isolated heavy and thundery showers on monday but with plenty of very warm sunshine across the uk, thereafter, high pressure builds strongly NE and intensifies over the top of the UK bringing a nationwide settled spell, the high then slowly migrates NE into scandi with a strengthening E'ly flow across the south but lighter winds in the north with an ongoing risk of frost but then later in low res there is a dramatic change to much colder, windier & unsettled weather, especially for the north.

Edited September 27, 2014 by Frosty.

[Gibby]

Good morning folks. A new day but any changes in the models. Here's my version of how I see the 00zs.

 

http://www.norton-radstockweather.co.uk/NEW-Model-Analysis(2859336).htm

[shaky]

Just when it looked like we were getting somewhere with the hint of unsettled weather on the ecm yesterday well well its no surprise to see high pressure back again until practically the end of the run!!!gfs has high pressure in total control till well after day 10 aswell!!!

[knocker]

Taking, I stress, a very superficial look it seems to me that while we keep the block in the western Atlantic we  are going to be subjected to the interplay of weather patterns concentrated mainly around the UK and the east.  Just looking at the hodgepotch the ECM ops anomaly has come up with this morning although the weak trough is apparent in the anomalies of last night.

Edited September 27, 2014 by knocker

[Summer Sun]

Away from NW Scotland where some rain & windier conditions are likely at times UKMO maintains the warm and dry weather

 

Edited September 27, 2014 by Summer Sun

[IDO]

The ECM mean anomaly suggests a blocked NH and I cannot see a return to a zonal flow in the next 10 days.

 

D10 ECM anomaly:    GEFS also eschewing the same pattern: 

 

Interestingly the models are still unsure for D5+ in how the current pattern evolves. On D6 the pressure spread from the GEFS for London is 16 hPa:

 

 Though all agreeing in a slow fall in pressure.

 

This is not confined to GFS, ECM at D5 has 6 clusters with the op/control being in the 5th highest cluster: http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa%21120%21pop%21od%21enfo%21enplot%212014011912%21%21

 

Ditto GEM:    

 

So still some uncertainty as to placement of higher and lower pressure from D6 on all models and no doubt that will influence the pattern after D10.

 

 

[Polar Maritime]

Some wild swings by the GFS out in the run this morning, A change in the current pattern to a cooler more unsettled outlook still looks to be there into week 2 of October. With some pretty extensive Northern blocking showing towards the end of the run over Iceland/Greenland, Dragging much cooler air down across Eastern Europe.

 

Edited September 27, 2014 by Polar Maritime
Wups.. Thanks Gav ;-)

[Frosty.]

The GFS 06z op run, like the 0z before it, becomes very anticyclonic during the course of next week and it's a little warmer than the earlier run with temperatures just above the seasonal average by at least a degree or two. The run becomes very blocked, so blocked in fact that atlantic lows are forced to slide SE to the west of the uk and undercut the block and then approach from the SE. After a mainly settled spell next week the run becomes more unsettled and cooler with a shallow trough in control but later in low res high pressure drifts to the north of the uk with a strengthening and rather cool E'ly flow, lots of northern blocking there, charts which would generate great excitement on here if it was january or february, it's certainly not a boring run, lots going on as we look towards early / mid october and beyond..a cooling trend.

Edited September 27, 2014 by Frosty.

[damianslaw]

I've refrained from looking at the charts over recent days, and whilst the reliable timeframe remains a continuation of the settled warmer than average weather we've had since the end of August - the overall longer trend is a cooling one (to be expected now we are entering October), with quite interesting developments suggesting a possible much colder source of air from the north - something we've not had since mid August.. Developments over North America with the shift of high pressure away from NW Canada are probably causing the models to show such possibilities - the downstream effect and a weak jet would certainly aid 'northern blocking' with energy transferred to the southern arm - this would be a major shift in the northern hemispheric pattern of recent weeks.

[Captain Shortwave]

So potential week 2 breakdown

Probably best at the moment to look a the mean charts, lets take day 10 and compare the GFS/ECM and GEM

GFS

ECM

GEM

It does look like a soft breakdown could occur with low pressure finally being allowed to drift towards Ireland with a ridge builds up the Eastern seaboard which will end the persistent broad Atlantic trough we have observed for nearly a whole month now. At this point though we can only speculate on how quickly this will occur, will heights to the east hold things up? Will a quicker breakdown occur? Or will this breakdown disappear like all the others this month. We will have to see.....

[Frosty.]

The experts view on things (met) continues to firm up on an unsettled and cooler further outlook with spells of wet & windy weather interspersed with brighter, showery days, proper autumnal weather appears to be on the way beyond next week, the further, further outlook is also for proper autumn weather with more rain and gales and in the settled interludes between depressions, cold nights with frost and fog.

 

As for the latest models, very good agreement now for an increasingly anticyclonic spell next week, even the northwest corner of the uk settles down for a time but as the high pushes further NE, the atlantic systems are likely to push up against the block and strengthen the sw'ly airflow across the far nw with unsettled weather returning, for most of the uk it looks like a decent spell of weather with pleasantly warm sunny spells, variable cloud and also a risk of overnight / early morning mist and fog, nights next week are also expected to become colder with a risk of ground frosts in rural areas, local air frost in prone frost hollows, a bit less cold in towns and cities.

Edited September 27, 2014 by Frosty.

[Summer Sun]

The first hints from UKMO of a potential breakdown of this high later next week especially in the north which ties in with today's met office update "Friday is expected to bring a return to rather unsettled conditions, with occasional wet and windy weather, and a risk of local gales. More settled weather towards the southeast"

 

 

GFS on the other hand keeps the high in place

 

[IDO]

Just to further highlight the uncertainty built into the models at the moment the cold upper flow on the 06z for N Europe has gone on the 12z and is displaced thousands of miles away towards Greenland:

06z: 12z:

HP most of the way on GEM 12z apart from a couple of days around D8 when an upper low forms, before HP builds back in:

GFS similar with the shallow upper low, but it sits further west, also around the same time:

It isn't till around D13 that it is pushed east across the UK:

Familiar by D16:

Shorter term; warm next week in the south:

D3: D4: D5:

Met latest 10 day also highlighting uncertainty for the end of next week but suggesting remaining relatively warm and dry for the South: http://www.bbc.co.uk/weather/features/29397066.

Edited September 27, 2014 by i'm dreaming of...

[Summer Sun]

Looking at t144 we have GEM and GFS going for high pressure

 

 

UKMO shows low pressure coming into play away from the south and SE

 

 

GEM and GFS both show the high declining but not as quick as UKMO

 

 

Just need to wait for ECM now and see what that brings at t144, will it follow UKMO or go towards GEM / GFS we'll soon find out

 

ECM is closer to UKMO than the other 2, next weekend is the current thinking for this high to breakdown

 

Edited September 27, 2014 by Summer Sun

[ANYWEATHER]

Ecm keen to bring the Atlantic in, during the later stages, gfs is rather half hearted.....

[Polar Maritime]

Can we please only discuss Model Output in here, There are other threads for MET forecasts.

 

Many Thanks, PM.

[MR EXTREMES]

one high declines but interesting seeing heights moving west to east or ne into greenland then possibly lower heights moving se be a server meltdown if this were mid nov or mid dec but interesting last few months with plenty of mid lat blocking.

 

and signs of high lat blocking allowing the first real unsettled autumn weather to make inroads on the uk.

although i feel this wont happen withing the next 10days delays in height removal have been some what common recently.

[knocker]

The feature of tonight's anomalies are the blocking HP in the western Atlantic, the possible weakening of the ridge to the east and the predominance of the fairly weak trough to the south west of the UK. The jet is meridional and fairly weak. This has all the atributes, as mentioned previously of no immediate dynamic Atlantic but a more localised low pressure area, albeit weak in the vacinity of the UK with some intermittent unsettled weather and about average temps. Further ahead no apparent major change.

 

[bryan629]

The feature of tonight's anomalies are the blocking HP in the western Atlantic, the possible weakening of the ridge to the east and the predominance of the fairly weak trough to the south west of the UK. The jet is meridional and fairly weak. This has all the atributes, as mentioned previously of no immediate dynamic Atlantic but a more localised low pressure area, albeit weak in the vacinity of the UK with some intermittent unsettled weather and about average temps. Further ahead no apparent major change.

 

Thats one cracking image for northern blocking knocker....if only it was December/January,,, 

 

I`ve been watching the model output for a few days now and it is non conclusive that as many are expecting the weather will be coming from the atlantic.... ECM and GFS have been through different runs hinting at an easterly type of pattern. 

 

It wouldnt take much for the high to our east or scandi to push northwards...given the slack flow of the PFJ

[knocker]

Borderline colder air next weekend with a trough just west of the UK orientated SW/NE

 

Edited September 28, 2014 by knocker