Model Output Discussion - 31/8/14 Onwards.

[ANYWEATHER]

I think the Iberian low will pose more problems than expected from tonights runs. I think there is a greater chance for the unsettled conditions to move further North, so thundery showers and a lot more can be expected during late week.  Ecm is keen to bring a change of weather at T+168, Gfs is not!  So will this month go out with out with a bang, or a whisper?

[Frosty.]

There are signs of change on tonight's Ecm 12z op run with the atlantic becoming much more active / aggressive during next week but before that, it's turning very warm from the continent with +10 T850 hPa extending quite a long way north but it's southern uk which turns hot for the time of year with mid to upper 20's celsius on thurs, fri and into the start of the weekend, cooling off a little from sunday but staying warm. The south is also the zone where heavy showers break out later this week with thunder very likely as very warm and increasingly humid air wafts further north but there will also be plenty of sunshine between the downpours, further north it will probably stay dry and as an atlantic high topples eastwards during the weekend it should fine up everywhere for a time, the atlantic high is important because it breathes new life into the blocked pattern across the southern half of the uk whereas scotland & n.ireland are never as warm as further south and then turns gradually cooler and fresher from the atlantic with increasingly changeable and breezier conditions.

 

Later next week turns progressively unsettled to the northwest with high pressure squeezed further south. There appears to be mounting evidence to support a marked pattern change later in the month with a more typical autumn pattern eventually becoming established, tonight the gfs and ecm 12z are pretty similar through low res...changes in the not too distant future

 

PS..sorry about the charts being out of sequence, I put them in the correct order but the computer says NO

[Captain Shortwave]

Still certainly a window (looks like Wednesday to Saturday) in which we could see temperatures reaching the mid-twenties. It does look like we will lose the robust ridge we have been enjoying for the past couple of weeks with a more defined breakdown to westerly conditions signalled for week 2. At that timeframe you would still wouldn't call the end of this settled spell for sure as a slightly weaker jet than forecast could result in high pressure remaining close to the UK.

Either way enjoy the summer-like conditions, this will almost certainly be the last this year.

[knocker]

Yes a long way ahead but the ECM ens is indicating a change by the end of the run. The Scandinavian block is giving away to the Greenland trough, Azores high pushed south and the jet established almost zonally central Atlantic (relative to the UK) bringing low pressure across the northern part of the Atlantic. At this stage the GFS is not in agreement. It's really a case of watch this space. It's loaded the charts backwards.

Edited September 15, 2014 by knocker

[Polar Maritime]

The Atlantic seems to be edging ever closer in the outputs, With the GFS showing the doors open around the 23rd, Maybe this time it will win out, The Models certainly seem to be playing with the idea, And more so than recent attempt's with some very Autumnal charts towards the end of 18z.  

 

 

Edited September 15, 2014 by Polar Maritime
From right to left.

[knocker]

The GFS 00z has a different take on the travels of Eduoard to certainly the METO and GFDL. Looking at a quick sequence it appears to have it absorbed by a low south of Greenland instead of nipping SE. Taking this at face value ( rather a big if ) is this disturbing the upper pattern sufficiently to bring about the change in status quo of which there are indications just down the line? Above my pay grade I'm afraid.

Edited September 16, 2014 by DiagonalRedLine
Charts re-ordered.

[Polar Maritime]

The GFS is showing a pretty cold Northerly by the 26th this Morning, Maybe even a chance of Snow for the Highlands/Mountains. Would certainly be a shock to the system if it materialised, Some "interesting" Model watching over the coming days as the Atlantic gains momentum.

 

Edited September 16, 2014 by Polar Maritime

[knocker]

The GEFS ens has joined last nights ECM in breaking the block.

 

[Frosty.]

It fills me with hope for the winter ahead when I see charts like this from the Gfs 00z for late september, cold air plunging south from the arctic is what I want to see regularly as we get closer to winter

 

In the meantime, an atlantic high to the northwest drifting southeast bolsters the blocked pattern during next weekend into the first ½ of next week, at least for southern uk but heights then fall to the northwest which heralds a more unsettled and much cooler spell, the azores high fights back but builds in further south, so I think as time goes on, high pressure won't have things all it's own way, atlantic low pressure (s) will feature more and more through late september onwards in my opinion.

[Summer Sun]

UKMO shows high pressure staying with the bulk of us into next week the one exception could be north west Scotland where pressure begins to fall slightly so increasing the risk of some showers or rain but else where its shown to remain dry and warm into next week

 

 

For once we have a full house for the 850's

 

[knocker]

The ECM appears to have thrown a bit of a wobbler this morning But then who knows!!!

 

Edited September 16, 2014 by knocker

[IDO]

^^^^ Hopefully they have thrown a wobbler with their Winter forecast as well:

 

 

  MattHugo81
Mid-Sept update of ECMWF Seasonal model shows a mild and wet winter overall, not a whiff of blocking. Same from EUROSIP, we shall see...
16/09/2014 11:41

 

Shorter term we still have no resolution with the post TS outcome. The 06z GFS op has the TS link with the lower heights to the NW, pumping up the low there: 

 

  That keeps the jet to the north allowing the Azores to ridge NE: 

 

So when the PV starts to establish itself we keep the higher heights in play a little longer: 

 

T300:   D16: 

 

The control sends some of the TS energy as per the op but some sinks south towards the Azores: 

 

Again by T300 we still have the PV getting organised and higher pressure close to the UK: 

 

So still indications are that this more settled weather has a fighting chance of holding out for most of September, more so for the south. Mostly showers on the GFS 06z op apart from one frontal pricipitation spike on D10. The jet remains to the North of the UK keeping the washout flow clear. Also a continued signal for a few runs now for another potential transient (2-3 days) warm spell at the end of the month (too early to take seriously).

 

The uncertainty remains prevalent in the ECM as well with D5 standard deviation and normalised SD indicating a very fluid setup, as we would expect from the introduction of the TS into the equation:

 

 

The ECM op is in cluster 2 (20 members total) at D5 so anything after D5 on this morning's run should be treated as no more than 40% likely and probably a lot less based on the suite as a whole. These TS do tend to bring a lot of flip flopping in the models and with the current slack flow producing poor verification stats any signal in FI should be treated with caution:

 

 The last few 10 day verifications showing very poor performance (even negative!).

[Frosty.]

 

 

 

  MattHugo81

Mid-Sept update of ECMWF Seasonal model shows a mild and wet winter overall, not a whiff of blocking. Same from EUROSIP, we shall see...

16/09/2014 11:41

 

I thought mild and wet was what we normally have in a british winter..nothing new there, at that range I will take that prediction with a large pinch of rock salt

 

As for current output, I think a change to more typical late sept / early october weather is on the way.

 

Edited September 16, 2014 by Frosty.

[johnholmes]

Is it possible to put the 'winter' outlooks in the winter thread please and keep this to model no further than 384h please?

[Polar Maritime]

Yes as John says, Can we keep all references to Winter in the Winter hopes thread please. And continue to discuss the Model Output in here. I have deleted a few off topic posts to keep this thread clean..

Many Thanks, PM.

Edited September 16, 2014 by Polar Maritime

[phil nw.]

Our slow moving pattern continues for the next week or so by the looks with a lot of high pressure across our side of the Atlantic.Just a few showers from that Iberian low over the next few days with some added warmth especially for the southern half.

 

Looking around the Northern hemisphere just a sign of the Polar regions starting to cool with quite a dig of colder air bringing some snow to parts of N.Siberia this week.We can see that deep trough over there modelled at T72hrs.

 

Little changing for us yet then but as the month advances signs already of a growing pool of cold further north.

 

[Bobby]

The most zonal run for a long time on the GFS starting from about +192, looks like momentum for a pattern change is building

 

Day 10

Edited September 16, 2014 by Bobby

[Summer Sun]

UKMO keeps high pressure going into next week

 

 

No 850's available this afternoon but I'd guess that temperatures will still be very pleasant for the time of year though temperatures in the south will probably be slightly lower than this week so low 20's rather than mid 20's

[Bobby]

GEM also showing the Atlantic roaring in with vengeance

 

[Frosty.]

The Gfs 12z op run shows the mini hot spell going out with a  BANG  across england & wales on saturday, lots of heavy showers and thunderstorms, with persistent rain for southern scotland, further north, a marked difference as it looks much cooler but brighter and drier as an atlantic high builds east, becoming cold at night across the north with widespread ground frosts for a time. The high drifts southeast to bring fine weather back to the south from sunday until midweek but much cooler and fresher compared to this week.

 

The already weakened block then crumbles in the face of an atlantic onslaught with cool, windy and unsettled conditions spreading from the west to all parts of the uk but especially for the north and west but later in the run the azores anticyclone builds strongly to the south of the uk and sets up home just to the SE across the near continent bringing warmer, drier and sunnier but still breezy weather,  however, the north and west stays windy, relatively cooler and generally unsettled, certainly the outlook has a good variety of weather.

Edited September 16, 2014 by Frosty.

[damianslaw]

GFS and others continue to show a change to something much more unsettled as we move through next week - with the Jetstream reinvigorating and heading straight to our shores. Jetstream forecasts also show this with an active flow moving into the country. Consequently this would be cooler windier and much wetter conditions for all, more so the north and west.

 

It is a case of waiting for the inevitable as we see cold pooling developing to the north and a marked temp gradient develop over NW atlantic fuelling the jet.  The current synoptics are preety abnormal for the time of year.

[Cloud 10]

Our slow moving pattern continues for the next week or so by the looks with a lot of high pressure across our side of the Atlantic.Just a few showers from that Iberian low over the next few days with some added warmth especially for the southern half.

 

Looking around the Northern hemisphere just a sign of the Polar regions starting to cool with quite a dig of colder air bringing some snow to parts of N.Siberia this week.We can see that deep trough over there modelled at T72hrs.

gfsnh-0-72.pnggfsnh-1-72.png

 

Little changing for us yet then but as the month advances signs already of a growing pool of cold further north.

 

An early taste of winter for parts of Scandinavia if the 12z ECM verifies at day 6,which gets the pulse racing a bit.

 

Edited September 16, 2014 by Cloud 10

[knocker]

Not putting this forward as a viable scenario at this range but the Atlantic may be cranking up a bit.  Cold air over Greenland pushing east with a ridge west Atlantic and HP to the east of the UK giving some quite bold winds at the 500mb level south quadrant of the low. Still slightly above average temps.

Edited September 16, 2014 by knocker

[Captain Shortwave]

ECM looking the least unsettled as we head into week 2

In fact the south probably would receive no rain at all with high pressure drifting west to east across southern Europe and the south of the UK. Is the ECM overdoing this or are the other models over-egging the strength of the jet coming off the eastern seaboard?

[ANYWEATHER]

Thundery rain for southern uk is likely and as been upgraded from previous and earlier runs, for late week. then High pressure builds making it settled for a time and colder, the Atlantic wakes up  for late month......

Edited September 16, 2014 by ANYWEATHER