Short range model discussion - into 2018

[knocker]

Quite nippy up north at 05 with a fair amount of mist and fog

[knocker]

The ecm has the low moving east over the weekend as the ridge starts poking it's nose north east but as ever the amount of energy flowing north east keeps a lid on this

Edited September 4, 2018 by knocker

[knocker]

Some min temps from the SYNOPS this morning

http://www.met.reading.ac.uk/~brugge/06.html

[knocker]

The 0900 geostationary sat. image

[knocker]

The high res. MODIS at 1230 UTC. Cracking day in the Scotland, west England and Wales although not that warm in the former at midday

[knocker]

Cool and unsettled Thursday and Friday and quite wet in the south on Saturday according to the ecm

And still this evening the problem remains with the ecm of too much energy exiting North America with the twin arms of the jet swinging around the very strong Aleutian ridge and low in the eastern Pacific intensifying across the atlantic and suppressing the attempts of the sub tropical high to ridge north

[knocker]

Merely an observation but a noted feature of last night's outputs was the continuing strength of the Aleutian ridge and the vortex over N. Canada. Something that also featured in the lower strat.

And also, and of more immediate interest, the imminent change to unsettled and cooler weather that has been well signposted of late.With that in mind the NH profile at Midnight and the surface analysis.

So today will start with clear skies in many places with a touch of frost around in the usual spots but some cloud lingering over some central areas where the weakening front is lingering and early om some showers in the south east, courtesy of the trough in the southern North Sea. But by late morning and through the afternoon cloud and rain will effect n. Ireland and western Scotland spreading east and south to north west England by evening.

As the ridge recedes overnight and through Thursday the front will continue to move slowly south east with the band of rain tending to peter out but introducing much cooler and unstable air in it's wake which initiates some very heavy showers over Scotland and later in northern England. Remaining drier in the south.

By Friday low pressure is centred over the North sea with a plethora of fronts/troughs running around the circulation which portends a cool day with plenty of showers, and some longer periods of rain as they merge, interspersed with sunny intervals.

A not dissimilar day on Saturday with perhaps some more persistent rain over England and Wales courtesy of a waving front

A pause here to have a look at the NH profile as it has some relevance to my opening comment with the Aleutian ridge and another offshoot from the vortex south east of Greenland and a very strong jet traversing the Atlantic keeping the sub tropical high pressure in check

Thus on the surface on Sunday the situation is quite mobile and although the North Sea low has filled the next one has arrived north of Scotland and a not unfamiliar scenario is becoming established of a N/S split with showery, breezy, conditions in the north and warmer and more settled conditions in the south as the ridge does manage to gain some purchase

.

 

 

[knocker]

Wet in the southern half of the UK on Saturday as a frontal system tracks east and then the familiar picture

The 0600 sat image

[knocker]

And my earlier comment vis the vortex remains very valid this morning

[knocker]

MODIS at 1134 UTC

[sparky1972]

im so hoping the weather for the south coast this weekend is not going to be as bad as i fear, we are at goodwood for the motor racing, so far the bbc forecast, met office and the weatheroutlook all say something different

[knocker]

The rain associated with the occlusion, currently effecting the west of Scotland

will move slowly south east during this evening and overnight becoming weak and patchy by morning. But the front trails back all the way to a low east of the tip of Greenland and a burst of more moderate rain might just impact N. Ireland as the triple point crosses Ireland during the early hours. Elsewhere the rain associated with another front just brushes the south east coast otherwise a pretty clear night for most and thus quite a cool start to the day tomorrow. But after a clear start patchy rain will move into Wales and the south west and frequent showers will kick off over Scotland.

 

[knocker]

This evening's gfs unfolding pretty much as expected

[knocker]

A frontal system crossing the UK on Saturday with perhaps the main rain belt concentrated over Wales and the Midlands

And then more systems track east as the twin flows across North America merge across the Atlantic largely suppressing the sub tropical highs attempt to expand very far north.

Edited September 5, 2018 by knocker

[knocker]

Much where the day stated. Strong Aleutian ridge and Canadian vortex, ably supported by the east European ridge and subsidiary low in the Iceland area resulting in a string westerly upper flow and no change in the outlook

[knocker]

No need for further comment on the outlook this morning so straight to the NH profile and surface analysis for midnight.

Overnight the front and patchy rain tracking south eeast down the country has weakened considerable so a fairly clear start to the day for many areas but there are exceptions. Still some showers in the east from the front in the North Sea and also creeping into western Scotland but the main area of rain, currently effecting Ireland

will track east across Wales and the Midlands courtesy of the triple point and cold front whilst at the same time the showers over Scotland will beef up a tad, with the possibility of some hail and thunder. Avoiding all of this the south will be sunny and quite warm whilst elsewhere cool with the temp a little below average.

Overnight the rain should clear from England heralding a generally sunny day but cloud will pop up during the day giving the odd shower in places but the developing low and associated front is adjacent to the east coast of Scotland so more concentrated rain will effect this area and even further down the east coast. And another generally cool day.

During Friday night and through Saturday the low moves east across the North Sea to Denmark but the front is still close to northern Scotland so patchy rain will persist here but the main problem will be the next frontal system arriving over Ireland by midnight and tracking east during Saturday accompanied by a large area of rain, heavy at times, generally concentrated over Wales, the Midlands and the north but not exclusively so.

By Sunday the rain would have cleared resulting in a broken cloud and sunny intervals day apart from the north west which will have some patchy rain, courtesy of the adjacent occlusion. Warming up a tad in England and Wales

But come Tuesday the next st stem is winging in from the west and by the afternoon cloud and rain are into N. Ireland and western parts of the mainland. Very much a N/S split vis the temp

Which brings us to the NH profile at T120 which is pretty much as has been alluded to in previous posts.

 

Edited September 6, 2018 by knocker

[knocker]

This morning's fax updates have modified the analysis for Saturday although the ecm has the rainfall much as before

And the next system arriving on Monday

[knocker]

The 0900 geostationary image

[knocker]

Good illustration of the front and showers on the 1500 sat image

[knocker]

The front and patchy rain should clear this evening along with the quite frequent showers further north resulting in a generally clear night for most and thus quite chilly by morning. The exception being the eastern coast areas of Scotland and north east England where it will be rather wet as the fronts curl around in close proximity.

[knocker]

Monday evening sees a frontal wave bring rain, and briefly quite strong winds to Scotland, and western regions as twin energy flows merge around the the high pressure All leading to a N/S divide

Edited September 6, 2018 by knocker

[knocker]

Not strictly just in the short range but the ecm is not without interest this evening. As far as I can see it takes the remnants of Gordon at T48 and then runs it up the east side of North America out into the baroclinic zone around Newfoundland where it merges with another low and then engages the left exit of the jet and deepens very quickly in mid Atlantic.

[knocker]

The outlook still generally unsettled but trending towards a N/S split in this emerging pattern.

The NH profile and surface analysis at midnight.

The front finally cleared the south coast resulting in a mainly clear night with just some bits ans bobs of rain in the north west and south west of England and more persistent showers around eastern and central areas of Scotland

The latter will persist during to today and slide a little further south to north east coastal regions of England where it will tend to be a tad cool in quite a stiff breeze. Elsewhere sunny intervals with maybe some fair weather Cu bubbling up so generally not a bad day.

But by 2100 the next frontal system will have brought cloud and rain into Ireland and this will spread ENE overnight and through Saturday mainly effecting Wales, the Midlands and the north of England with some heavy bursts on occasion. Much of Scotland and the far south should stay dry. Temps around average.

The rain belt clears into the North Sea by evening but at the same time another little wave is bringing some more rain to west Wales and this tracks north east overnight and through the early hours of Sunday.before clearing the east coast of Scotland by early afternoon, by which time some hefty showers are starting to impact the west coast of Scotland as the front associated with the main low to the NW edges closer. Further to the south and east sunnier and drier.

Monday and Tuesday we are very much in the N/S split territory with Monday starting breezy and sunny, apart from northern Scotland, but the next frontal system is on it's way tracking very quickly east north east

which brings rain to the north on Monday which slips further south on the trailing front on Tuesday. The front very much the dividing line between the airmasses

And the not unfamiliar NH profile at T120

 

Edited September 7, 2018 by knocker

[knocker]

The gfs has the remnants of Gordon connected to our trailing front on Monday before finally merging it with the other low in mid Atlantic. The gfs is quite bizarre in the latter stages as it struggles with an intensifying Florence and the other TSs following.

[knocker]

The ecm not dissimilar to the gfs Mon/Tues

And the 0600 geostationary image