Model Output Discussion 1200 hrs 30/09/14

[Milhouse]

http://modeles.meteociel.fr/modeles/gfs/runs/2014101306/gfs-9-150.png?6

 

One or two getting a bit carried away about this weekend's so-called "Heat wave". I would imagine 21c has been reached on any number of occasions in mid-October over the past twenty years and to be honest the 6Z Operational output doesn't look that brilliant for heat. What we don't know (but can suspect with experience) is that the fetch will bring in a lot of cloud and drizzle to south-west facing coasts so for the high temperatures we need to see cloud breaks and sunshine develop inland.

 

Simply having an 850 of 16c over us under cloud and drizzle means nothing - the synoptic set up may get us to 20c but without significant cloud clearance (and I don't know if we can predict that yet) we won't get much higher at this time of year.

 

We can only go on GFS predictions so far and a look in the October CET topic will show some daily records are under threat going by the 6z.

[Captain Shortwave]

Very touch and go with respect to how warm and bright the weekend will be. Central/Southern England looks ok at the moment with enough of a southerly element to allow sunshine to break through. Not so good for the north and west with rain at times.

The GFS does have temperatures into the low twenties over the weekend

22/23C possible in the south east on both days. Not bad for mid-October.

Beyond there is a lot of action near the Eastern seaboard which needs watching as this will determine how our weather will be like next week.

 

As PM says conditions over the pole still look decent enough with the weak Arctic heights still in place throughout low resolution. GEM likewise.

Edited October 13, 2014 by Captain shortwave

[Ali1977]

Nothing remotely cold in the GFS forecast, however it is only mid October. The PV looks to remain a little broken throughout the rest of Oct, this gives hope going into November that something colder may materialise for those hoping to see some early cold. It wouldn't take much to get colder weather in November than the whole of last year in my neck of the woods; I think I only scraped the car twice.

[knocker]

Yet another TS

Edited October 13, 2014 by knocker

[Polar Maritime]

 

GEM likewise.

 

And ECM to CS 

[Captain Shortwave]

ECM if anything trumps the others for this weekend

12C isotherm covering the whole of England with 850s in the mid-teens in the south east. With the flow from the south then temperatures could soar in any sunshine. 

Into week 2, whilst the Euro ridge loses its grip on the UK, the ridge still continues to benefit us with a decent pulse of WAA towards Svalbard.

Edited October 13, 2014 by Captain shortwave

[Yarmy]

Yes, at this time of year my attention is drawn east to see if a decent cold pool is being built. The ECM is certainly showing that:

http://www.meteociel.fr/modeles/ecmwf/runs/2014101312/ECH0-192.GIF?13-0

Something for everyone on this run.

[Man With Beard]

ECM if anything trumps the others for this weekend

12C isotherm covering the whole of England with 850s in the mid-teens in the south east. With the flow from the south then temperatures could soar in any sunshine.

yep I'm with you CS, should the ECM verify (and that's a big if), the direct southerly would mean temps over France will be nearly matched in the SE, so maybe just maybe 25C could be reached. When was the latest ever 25C in the UK? Touch and go though, it requires the Atlantic front to wait until evening to move in. I still think the decent weather will be far more limited to eastern regions.

[Newberryone]

Ecm 12z op ending a second run on a potentially less unsettled note with further ridging from the southwest a distinct possibility

[knocker]

Tonight's anomalies showing little change in the general pattern. Troughs south Iceland and eastern Europe, ridge N. America with warmer air orientated west/east Atlantic to N. Europe.

 

Both the GEFs and ECM have a surface analysis consistent this giving an Atlantic dominated by low pressure with a low situated to the NW of the UK. Thus a continuation of the unsettled conditions with average temps.

 

Further ahead little change with this except perhaps warmer air to the east and the hp to the south pushing further north but given the time frame this is not of great significance still giving the low pressure dominating the Atlantic.

 

The ECM has the jet pretty much zonal and very static.

 

[Captain Shortwave]

yep I'm with you CS, should the ECM verify (and that's a big if), the direct southerly would mean temps over France will be nearly matched in the SE, so maybe just maybe 25C could be reached. When was the latest ever 25C in the UK? Touch and go though, it requires the Atlantic front to wait until evening to move in. I still think the decent weather will be far more limited to eastern regions.

We will have to wait and see, the ens show a weaker pulse along with a more south westerly flow. But at just 5/6 days away, it is more than just a tease. Will await the 00z suite with interest. I would also love to see the ECM and other models throw out a Svalbard/Scandi high like tonight's ECM did too to help build snow cover in Russia.

[Gibby]

Large rainfall totals likey to amass across parts of the UK in the coming weeks as the Jet flow ratchets up with warm moist air over the UK and Low pressure coming together to deliver the potential for very wet and windy conditions at times for the coming 10-14 days at least.

Edited October 14, 2014 by Polar Maritime
I've moved a chunk over to the Winter/hopes thread, Can we stick to Model Output Discussion in here please, Many Thanks.

[Bobby]

Yes cyclonic westerlies look to dominate for the forseeable, ECM mean at day 10. Nearest below average uppers in N. Africa

 

 

Day 12 NAEFS surface temp anomalies, very mild across all Europe.

 

Edited October 13, 2014 by Bobby

[knocker]

A glance at the ECM weeklies. Look familiar.

 

[Captain Shortwave]

UKMO looks quite keen on keeping high pressure close by into next week

The warmth would be retain as well.

 

GFS/GEM, not so keen on even much of a warm up this weekend as we receive more of a moist South westerly flow.

 

What way will the ECM side?

[knocker]

Not much different to GEM

 

[Polar Maritime]

Some very Wet and Stormy weather showing for around the 26th this Morning. The S/W would get a real battering out of this.

 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY OCTOBER 14TH 2014.

 

NEXT UPDATE WEDNESDAY OCTOBER 15TH 08:00

 

THE CURRENT GENERAL SITUATION. A weak Low pressure near East Anglia will fill up as a front attached to a deep mid Atlantic Low pressure moves NE over England tomorrow.

 

MODELS-2 WEEK HEADLINE  Changeable weather with some rain at times but with some dry and very mild weather likely in the South and East for a time. Windy at times.

 

THE JET STREAM ENSEMBLE FORECAST The Jet flow will strengthen somewhat across France tomorrow before trending North across the UK on a SW to NE axis towards the weekend before returning back South on a more West to East axis for a while next week. Clarity becomes more clouded later in the period but the general theme is for a relatively strong flow to continue to lie in the vicinity of the British Isles in a undulating pattern.

 

GFS The GFS operational today shows a deep mid Atlantic Low pressure moving slowly NE towards the weekend enabling a mild or very mild but strong SW flow to establish over the UK with troughs delivering some heavy rain at times especially across the West and North. Through the weekend and week 2 the flow veers more towards a Westerly point with cooler conditions developing but no less changeable with spells of string winds, rain and showers all featuring for all areas on occasion in week 2 with temperatures returning to more average levels.

 

THE GFS ENSEMBLES. The GFS Ensembles are in agreement with the operational in format with the caveat that next week will see a typical Westerly type Autumn setup with Low pressure areas crossing East to the North of the UK each delivering bands of rain followed by showers and fluctuating temperatures between somewhat above average in the strong and mild SW'lies and rain to somewhat below in the colder NW'lies behind each departing Low pressure.

 

UKMO UKMO this morning shows High pressure holding firm over Southern Europe at the weekend with an active trough of Low pressure out to the West making slow and erratic progress West to East feeding rain in from the West and displacing the mildest of the conditions away from the SE

.

THE FAX CHARTS  The Fax Charts indicate a very mild or even warm SW flow over the UK towards the weekend. The atmosphere is shown to be littered with troughs feeding NNE in the flow and tempering any thoughts of sunshine as cloud and outbreaks of sometimes heavy rain continually feed NNE in the very mild flow.

 

GEM The GEM operational today shows a very mild SW flow in the short term gradually veering Westerly later in the weekend and making for changeable Westerlies next week between Low pressure to the North and High pressure to the South. All areas would be at risk of rain next week in average temperatures with the sometimes strong winds delivering most rain to the North and NW with longer drier spells towards the South.

NAVGEM NAVGEM simplifies the general theme of very mild SW winds and rain at the weekend veering Westerly next week and cooling down somewhat in a continuing basic unsettled theme. 

 

ECM The ECM operational today also underlines the theme shown by most output that after the deep mid Atlantic Low moves NE and away to the North at the weekend it opens the door for cooler and unstable Westerly winds to take command next week with rain at times. After some very mild values at the end of this week and start to the weekend temperatures will fall off to average next week in a blustery West wind.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend is still towards the milder weather later this week being replaced by something cooler and still unsettled next week but the options are widely scattered within this general theme.

 

MY THOUGHTS  The general theme of less mild weather moving across the UK from the West at the weekend is maintained this morning as a deep mid Atlantic Low moves NE to the North of the UK and tilts the SW flow to a more direct Westerly later delivering changeable weather with rain at times next week as successive troughs and Low pressure areas move East across the Atlantic and over or close to Northern Britain. There are small variations shown between the models on this basic theme mainly hinging on the possibility of higher pressure ridging up close to Southern Britain on occasion and bringing brief spells of drier and less breezy weather in the South before the next Low and troughs displaces it. With this Westerly aspect to the weather temperatures will never fall low and frost and fog will be very limited to ridges behind passing Lows. Equally there may be periods of strong winds when gales are a possibility but it looks unlikely that anything out of the ordinary given the time of year is likely. So putting a broad brush over the next few weeks it looks like typical mid Autumn weather with rain and showers at times along with occasional strong winds and some drier and brighter periods, these chiefly over the South in average temperatures overall once the up and coming very mild interlude gives way later in the weekend.

[Frosty.]

I take a lot more interest in low res output from this time of year onwards when it shows different shades of blue building up to the NW and the Gfs 00z op run shows a trend towards colder weather with temperatures slipping below average through FI, colder and stormier at times..it's only a matter of time before that mass of bottled up arctic air is uncorked and covers the uk in lovely blues..Please make it so..I mean snow..it can snow in late october as we have seen in recent years

[knocker]

One could say a very disjointed jet

[Nick L]

The latest monthly ECM shows a fairly zonal picture continuing, with cool and unsettled weather the theme of the next few weeks. Hardly any hint of a first taste of winter as we go into November on the first of this week's update.

[phil nw.]

The latest monthly ECM shows a fairly zonal picture continuing, with cool and unsettled weather the theme of the next few weeks. Hardly any hint of a first taste of winter as we go into November on the first of this week's update.

 

Not much to add really.We only need to look at recent modelling to see the way the NH pattern has evolved.

Yes there still +ve height anomalies over the pole and can appear quite alluring but when the one area of lower heights are to our NW towards Greenland with a corresponding Euro/Azores +ve anomaly then it can mean only one thing.

The ECM mean charts at day 10 anomalies/and 500 pattern along with last nights NOAA mean forecast for days 8/14.

 

it may cool off somewhat in week 2 after the weekend warm pulse as the jet flattens out bringing in the flow more from the west or north west at times but really we are just looking at our normal Autumn set up.

[Frosty.]

The latest monthly ECM shows a fairly zonal picture continuing, with cool and unsettled weather the theme of the next few weeks. 

cool and unsettled is a good solid base to build on and brings an increasing risk of occasional wintryness to northern hills, hopefully we will see the jet tilt more towards northwest / southeast during late oct / early nov..the cold will come, I don't anticipate the type of mild dross we had for most of last winter this time.

[Nick L]

cool and unsettled is a good solid base to build on and brings an increasing risk of occasional wintryness to northern hills, hopefully we will see the jet tilt more towards northwest / southeast during late oct / early nov..the cold will come, I don't anticipate the type of mild dross we had for most of last winter this time.

 

Yeah the unusually warm temperatures this weekend will certainly be a temporary thing, with a more west-northwesterly flow following the weekend and for the foreseeable. Although it wasn't really *that* mild last winter to be honest, rather the total absence of cold that was notable. But that's for another discussion!

[knocker]

The temporary weekend at 06Z