Model Output Discussion 01/09/17

[Frosty.]

Models are looking exciting to me, proper autumn weather.

[Summer Sun]

The ECM London ens maintains a steady rise in pressure from Tuesday

[knocker]

[mb018538]

The main trough may begin to lift out and push east by day 9/10, but that's a long way off at present. For the meantime, prepare for plenty of wind and rain!

[ACCOUNT DELETED]

One thing that has been shown by GFS and a few other models for the last few days is high pressure building in from the West by mid September, so hopefully a big improvement for many areas with relatively mild sunny days and cool nights. 

[ACCOUNT DELETED]

GFS 6z has got the high building in from next Friday, a day earlier from the 0z. No guarantees of course but it's been showing this trend now for a few days. 

[Summer Sun]

A growing trend for a few runs now is that Tuesday will be a fairly decent day with a ridge of higher pressure and just a few showers

[Summer Sun]

GFS and ECM both in agreement for a ridge of higher pressure on Tuesday UKMO getting there

 

[knocker]

The gfs and ecm are more or less on the same page with a continuation of the unsettled weather in the reasonable time frame albeit differences with the detail.

This evening the ecm has the next low 974mb centred south of Iceland 12z on Sunday with associated fronts lying Scotland/west Irish Sea. Over the next 24 hours they all move east bringing rain followed by hefty showers  and strong W/NW winds particularly in Wales , N. Ireland and England. Thus by 12z Monday the low is over Scotland.

On Tuesday some brief transitional ridging before the next set of fronts, and rain, arrive by 00z Wednesday in the strong WNW flow with the jet in the region of 130kts. These track quickly east and the depression north of Scotland tracks SE into southern Norway introducing a coll showery airstream over the UK. In this fluid pattern one suspects that this is open to changes still next week.

 

[Frosty.]

A really good / happy ending to the Ecm 12z with high pressure building in strongly and settling our weather down nicely for mid month and hopefully beyond.

[SMU]

Worth a mention....

ECM 192 shows an area of -2- -3c uppers covering Scotland in a brisk North west wind

certainly an opportunity for a Frost T'up north - maybe even some wintryness over the Scottish mountains!

[Summer Sun]

Not a great deal of change from Monday's London mean to tonights for the 11th

4th it was around 993mb

Tonight it's around 995mb

Edited September 7, 2017 by Summer Sun

[phil nw.]

A mid-month Atlantic high toppling in seems the favoured option on current modelling.

As SM pointed we can expect a much fresher and cooler feel from that nw wind

So an early chill in the air with temperatures dropping quite low at night in some places.

Edited September 7, 2017 by phil nw.

[Frosty.]

Beyond the next week or so of generally unsettled weather there are very promising signs of a more settled period of high pressure and tonight's Ecm 12z ensemble mean shows this. It would be nice to have a spell of fine days with long sunny spells and light winds and chilly nights with mist / fog and a risk of slight frosts from mid september..fingers crossed. 

Edited September 7, 2017 by Frosty.

[knocker]

The  Atlantic trough(s)/Azores High pressure complex continues to nudge east during last evening’s ten day anomalies, and in to the ext period, but there is no agreement on the pattern whilst doing so.. By this I mean the orientation and intensity of the Azores high pressure and trough in the eastern Atlantic. The ecm appears far more bullish with the HP for example. Quite important as this will dictate how much influence the Azores will have on the UK and direction of travel of any troughs in the medium term.

At the moment the percentage play, in general terms, remains unsettled with the upper flow from the NW with temps below average before the end of next week becoming more settled for a time, particularly in the south, with temps picking up quite well but quite a diurnal variation. As usual the detail will be sorted by the det. runs

Back to the here and now and more detail. The low currently to the NW of Scotland will drift south east during the day and at some point most areas will be subject to heavy showers or longer periods of rain Tomorrow the showers will be less frequent but by Sunday the next low has arrived 978mb to the north west of N. Ireland with the associated fronts lying down the west of the UK. These will track east bringing rain to most areas, followed by frequent showers, with some strong westerly winds.

Over Monday the low swings NW towards Norway veering the SW north westerly and continuing showery and then some very transient ridging on Tuesday before the next quite intense low arrives 983mb NW of Ireland by 1800. The low continues to move east over the next 24 hours with the fronts traversing the country and by 18z Wednesday is over NE Scotland with the country once again in a showery north westerly.

From this point the not totally unexpected amplification of the Azores HP to the west occurs and it is here that the orientation of the surface high  is critical. and on this morning's  gfs it's looking okay with more settled weather generally, the far north perhaps the exception, with temps rising above average but with a fair diurnal range.

 

 

 

Edited September 8, 2017 by knocker

[mushymanrob]

10 hours ago, Steve Murr said:

Worth a mention....

ECM 192 shows an area of -2- -3c uppers covering Scotland in a brisk North west wind

certainly an opportunity for a Frost T'up north - maybe even some wintryness over the Scottish mountains!

just what we need before things warm up, thus producing a real 'indian summer'
 

[knocker]

By 12z Tuesday the ecm has the new low centered over NW Ireland with  the fronts impinging Wales and the south west. So plenty of rain on Tuesday and by 00z Wednesday the low is over NW England and the fronts just clearing the south east.

Twenty four hours later the low is in the eastern North Sea and the UK in a Showery NW/N airstream  This continues through Thursday/Friday but the showers become far fewer as the Azores ridge pushes north east by saturday 00z. This could produce some quite cool overnight air temps down as low as 4C in the south even.

Given the differences between the gfs and ecm towards the end of next week merely highlights the uncertainty and neither taken as gospel at this stage.

 

[Summer Sun]

Sunday see's a deep low moving into Scotland this will give some rain and gusty winds during Sunday and overnight into Monday

By Monday it's self this low pulls away and the rain becoming far less widespread with temps ranging from 15c in Edinburgh to around 20c in London

[ACCOUNT DELETED]

Doesn't look as though we'll see a decent day next Tues on the GFS 6z as was forecasted yesterday but high pressure slowly builds by Thursday especially in the south. This has been indicated for a good few days. 

[Summer Sun]

12 minutes ago, DJ RY said:

Doesn't look as though we'll see a decent day next Tues on the GFS 6z as was forecasted yesterday but high pressure slowly builds by Thursday especially in the south. This has been indicated for a good few days. 

Still looks dry for most away from the west well into the afternoon or early evening

 

Edited September 8, 2017 by Summer Sun

[ACCOUNT DELETED]

8 minutes ago, Summer Sun said:

Still looks dry for most away from the west well into the afternoon or early evening

 

Yes better weather further East but for my location near Swansea it looks wet and often very windy with no dry day at all between now and Thurs if the GFS 6z is correct.  

[Summer Sun]

GFS 12z has Tuesday's low a bit further west than the 06z did which keeps the rain further west

12z                                                                  06z

[knocker]

Quite a nifty looking low next week. The ecm has it over N. Ireland by 18z Tuesday with rain and fronts already into western parts. By 00z it is over SW Scotland with the fronts clearing to the east and the possibility of gales, briefly,  in the Lancashire area in the westerly airflow behind. We could be looking at a couple of inches of rain in the NW.

Edited September 8, 2017 by knocker

[Frosty.]

Following the generally cool, breezy unsettled conditions for most of next week the Ecm 12z shows a wonderful recovery later with high pressure building in with increasing day time warmth and sunshine from towards the end of next week onwards, especially further south.

[knocker]

Some consolidation this evening of perhaps a more settled spell towards the middle of September. Can't post the EPS but it is also looking okay.

Just to reiterate the position of the surface high is paramount but at this stage looking okay except possible for the north at times. Temps should rise above average a tad later in the period but  keeping in mind a fair diurnal range is on the cards.

Edited September 8, 2017 by knocker