Model Output Discussion 01/09/17

[knocker]

Quite a good illustration of the split upper flow adjacent to the UK which could influence the direction of travel of depressions east then south east.

[Frosty.]

The Ecm 12z shows some welcome respite from all the changeable / unsettled weather later in the run with high pressure building / ridging in during early october.

Edited September 25, 2017 by Frosty.

[ANYWEATHER]

Hello Folks , the Calm before the storm...Perhaps , but a few days of benign weather before we enter a very turbulent and aggressive  jet streamLate weekend into early next week the potential of a major Autumn storm , remnants of the ex hurricanes etc. A strong jet stream of 200 mph plus may well lead us into the most stormy Autumn storm for a good many years   .

[Newberryone]

Latest Ecm indicating quite a rapid settling down or at the very least overall improvement from day 8 with the jet being pushed further north, unlike the previous run. Question remains as to how much credence one can give this sudden change considering the present volatile weather picture. 

Edited September 25, 2017 by Newberryone

[knocker]

 I was about to post on the same lines. The EPS anomalies tonight are also indicating a pattern change with Atlantic trough weakening and the Azores pushing north in the vicinity of the UK. And equally to the point in the ext period (can't post) it rapidly loses the strong ridging to the east so a weakening Atlantic flow backing south west with the Azores building wand positive anomalies over the Atlantic and Greenland with temps over the UK edging above average The GEFS is nodding in that direction

 

Edited September 25, 2017 by knocker

[Iceberg]

Both ec ops and ctrl have quite a potent storm sun/mon kind of time. Mean speeds of 40-50 mph in the south, but eps puts the winds anywhere from Scotland to north France. 

[knocker]

I suspect I may have been grabbing a little at straws last night leaning very much towards the latest EPS without NOAA being that keen. Need to wait and see what today brings forth for the medium term

Meanwhile today and tomorrow are not looking at all bad for most areas. With a light S/SE drift temps in some areas could reach 23C and with the front fizzling out it could be quite sunny once early morning mist has cleared. The caveat to this is that by tonight and tomorrow morning the next low will arrive west of Ireland and the associated fronts encroaching so wind and cloud will increase from the west as tomorrow progresses but still time for most places away from the west to have a pleasant day.

The aforementioned fronts cross the country later on Weds and overnight to be in the North sea by 12z Thursday with the next depression 970mb and associated fronts to the west of Ireland. The low drifts up towards Iceland and the fronts, after some transient ridging Thursday, bring more rain to most areas on Friday.before clearing into the North Sea by evening. Thus by 12 Saturday we again have transient ridging but ex tropical storms Maria and Lee are girding their loins out west.

They quickly get organised and form a deepening depression that tracks quickly ENE on a very strong upper flow and could well bring gusts in excess of 70 kts to northern Scotland in the early hours of Monday.Windy and wet for the rest of the UK on Sunday as well  But it must be stressed that this depends on the precise track and intensity of the low and this is not as yet anywhere near definitive and for the moment  the more southerly track and the duck southeast does appear to be off the table.

.

The low clears away to the NE as quickly as it arrived leaving the Azores to ridge in but best left here. So all in all after a good couple of days then changeable with rain and gales over the weekend and beginning of next week.

 

Edited September 26, 2017 by knocker

[johnholmes]

I suspect I may have been grabbing a little at straws last night leaning very much towards the latest EPS without NOAA being that keen. Need to wait and see what today brings forth for the medium term

Yes I think it needs aday or two to be more sure of just which way the anomalies will go. Although the EC-GFS outputs have twice this month ourdone NOAA, something that never used to happen.

[knocker]

As I said earlier nothing definitive about next weekend.and ex tropical storms as yet

The ecm is completely different to the gfs even at this range. By 12 Saturday it has developed the nest system swinging in from the west far more than the gfs and has a low NW of Ireland with fronts and rain into same, The fronts sweep across the UK developing little disturbances as they (it) go thus a very wet and windy Saturday night and Sunday before the fronts reach the North Sea.

At the same time Lee has lost it's identity to the west and Maria a way west of Cornwall and  is about to drift south east and do the same.

[Summer Sun]

Once the weekends low pulls away UKMO and GFS have a similar idea showing higher pressure edging up from the southwest

ECM has a different idea with the low centred to the NE bringing northwesterly winds our way

[knocker]

The EPS this morning is still indicating a weakening of the HP/trough axis towards the end of the 10 day period and into the ext with the Azores ridging from the SW in the vicinity of the UK. Thus the upper flow backing SW and temps rising to maybe a little above average, This would at least portend drier conditions in the south but it's a bit on it's own at the moment.

[knocker]

For another variation on a theme the gfs this evening does not have Lee and Maria merging but gradually tending to lose their identity and ending up has frontal features, one down Ireland and the other further to the west, by 12 Sunday with the main low just SW of Iceland. Still potential for a very windy and wet Sunday/Monday particularly in Scotland (60-70Kts gusts) and possible developments on the front(s).

 

 

Edited September 26, 2017 by knocker

[Dorsetbred]

50 minutes ago, knocker said:

For another variation on a theme the gfs this evening does not have Lee and Maria merging but gradually tending to lose their identity and ending up has frontal features, one down Ireland and the other further to the west, by 12 Sunday with the main low just SW of Iceland. Still potential for a very windy and wet Sunday/Monday particularly in Scotland (60-70Kts gusts) and possible developments on the front(s).

 

 

Well, these two like to keep everybody guessing don't they? 

[knocker]

7 minutes ago, Dorsetbred said:

Well, these two like to keep everybody guessing don't they? 

Don't they just. Be interesting to see what the ecm comes up with. I'm thinking it's all to do with how they engage with the jet at the end of the week, In this chart you can see they are still to the south.

Edited September 26, 2017 by knocker

[knocker]

The ecm is more or less sticking to the last run where it doesn't engage either Lee or Maria with the main trough and has them south of the Jet. Lee loses it's identity and Maria slips south east and does likewise

The main impact on the UK is from the main trough which tracks east and deepens riding on the jet  The associated fronts with heavy rain and very strong winds impact the UK Saturday evening through Sunday with the center of the low 974mb adjacent to the Hebrides by 18 Sunday.

Needless to say the detail  is still a long way from being done and dusted.

[ANYWEATHER]

Evening All , Massive differences between gfs and ecm at the T+96 to 120 timeframe  All I can say is "WOW" gfs clears exMaria into the jet stream much quicker than ecm , will be interesting viewing in the next few days , all I can say is be prepared .....

[Meteorite58]

Interesting how the latest GFS and the UKMO are beginning to look similar Sun into Mon. Very strong winds showing up in the GFS and the system begins to stall as it gets sandwiched in by blocking HP , that could mean strong winds for longer and more rain for longer. 

 

 

 

Edited September 26, 2017 by Meteorite58

[mb018538]

GFS and UKMO look a bit blowy today as ex-Maria/Lee make their way across the UK, with gales in the NW for a time, and higher pressure building in behind (best in the SE, as usual). This one is still going to  take a number of days to sort out, as we still don't know how these systems are going to fully interact with the jet.

[knocker]

Today dawns fine for all apart from mist and fog patches in some areas but increasing amount of cloud in the west as a complex frontal systems edge east bringing rain to the far west this morning.(The rain band is currently just reaching St Just). This will track east during the day clearing the east overnight to to give a pleasant enough day tomorrow with little wid.

This brings us neatly on to the gfs and by 06 on Friday sees the next Atlantic depression south of Iceland 974mb with the associated fronts and rain lying down the western side of the UK. These traverse the country during the day and clear east to be replaced on Saturday by some transient ridging as the main low tracks east  At the same time the next Atlantic low is tracking east with associated fronts along with ex tropical storms Maria and Lee.who are both just south of the Strong WSW jet.

Fast forward 24 hours and the main low is just south of Iceland 975MB with fronts and rain down the Irish Sea and Lee has lost it's identity. (the gfs has been pretty consistent with this) ans Maria is also about to. Not forgetting of course that they have been absorbed into the main system which continues to bring another heavy band of rain into the UK and strong winds through Sunday into Monday. With the main low tracking slowly east and the Azores ridging behind the passage of the lows the jet is pushed south over the UK.

From here a rather breezy, showery north westerly. before the next system arrives midweek and the analysis has a very familiar NW/SE look about  it.

[mb018538]

ECM quickly whistles the low through before building a nice anticyclone to settle things down:



Also turning very warm with 850s above 12c:



Temps into the low 20s, with overnight fog more than likely given it will be October!

Very different to the 12z last night.....more runs needed!

Edited September 27, 2017 by mb018538

[knocker]

The gfs and ecm are still a long way from being on the same wave length even within a short time frame.

At midday Saturday the latter has a small low over Ireland which moves quickly across the north of England Scotland bringing copious amounts of rain and heavy blustery showers to Wales and England in it's wake.

By 00 Sunday the main low and fronts have reached western Ireland and these sweep across the UK during the day bringing more rain and strong winds (gales?)

Whilst this is going on Lee has lost it's identity and what is left of Maria is a fair way west of Cornwall about to swing south east and perhaps bringing some rain to the south west on Monday

They never engage with the strong jet running just the north into the UK.

Edited September 27, 2017 by knocker

[Frosty.]

The Ecm 00z is a pleasant surprise this morning with high pressure building in strongly during next week..I think most of us would be happy with this in early october!

[weatherguru14]

4 minutes ago, Frosty. said:

The Ecm 00z is a pleasant surprise this morning with high pressure building in strongly during next week..I think most of us would be happy with this in early october!

how can they or you  predict that? when on Monday (two days ago) they had wide spread sunshine for today. Most likely that   will be cloudy high.. Because its IMPOSSBLE..to get a day that as clear skies from dusk to dawn

[ANYWEATHER]

3 minutes ago, weatherguru14 said:

how can they or you  predict that? when on Monday (two days ago) they had wide spread sunshine for today. Most likely that   will be cloudy high.. Because its IMPOSSBLE..to get a day that as clear skies from dusk to dawn

It won't happen there is a very high level of Shannon entropy or very uncertainty ,charts posted like that are merely for amusement 

[Frosty.]

The Ecm 00z ensemble mean / like the operational shows high pressure in the ascendancy during next week with increasingly pleasant surface conditions developing, especially across the southern half of the uk with warm sunny spells and light winds followed by chilly nights where skies clear with mist / fog patches. 

Edited September 27, 2017 by Frosty.