UK meteorology

Malcolm's post for 9th (part 1):
After a relatively cool night today will dawn quite dry and bright in most places but frontal rain will ingress N. Ireland and the Western Isles by 0900 and will slowly cross the country during the day and evening. Thus most of the eastern half will remain dry and pleasant with temps still above average before the rain arrives and clears unto the North Sea by Thursday morning.









So once rain has cleared Thursday wil generally be a dry and sunny day with showers, more frequent in the north, as a transient ridge becomes briefly influential, witrh temps back to around average.



But by Friday the battle between the eastbound energy exiting North America and the block gets underway in earnest with the block to the east unrelenting and the Bermuda high amplifying in the Atlantic deconstructing the trough. Thus the surface low south of Iceland is almost stationary as the associated front struggles to push east across Ireland in the gently southerly flow over the UK. So again the eastern half of the UK remaining dry and generally temps still around average.



 
Part 2:
The front eventually clears into the North Sea early Saturday and as the low south of Iceland slides SSE and loses it's identity all is pretty quiet over the UK with sunshine and showers, probably more frequent in the west with the odd trough popping up, with temps still around average.





And thus by 00 Monday we are left with this intriguing position vis the battle between the energy and the block


The ecm has the filling low sliding down west of Ireland Saturday with slack low low pressure over the UK with the front slow to clear East Anglia on Saturday. Quite interesting how this morning's runs are migrating the Scandinavian ridge.

 
Malcolm's thoughts as of the 10th Part 1:
The front and rain belt has continued to track east across the country overnight giving some heavy bursts of rain in places and it will be slow to cleat East Anglia and the south east this morning and probably wont until early afternoon. Behind the front a much cooler airmass for all but probably plenty of sunshine albeit interspersed with showers, particularly in Scotland where they could be quite heavy, and possibly thundery in the east later. The showers will tend to subside overnight thus a clear night, on the cool side in places, before the front and next belt of rain arrives over Ireland by 1200.







The front will stagger east across the country during the rest of Friday decaying as it goes bringing patchy rain in western areas and freshening winds in the north but again not too bad in the east

 
Part 2:
The general analysis at 1200 Saturday finds that the Atlantic trough has been split by the burgeoning Bermuda high pressure and the continuing resilience of the block to the east creating a cut off upper low just to the west of the UK. All of this results in a surface low north west of Ireland with the UK in a very slack gradient and rather cool changeable conditions with heavy showers, perhaps thundery, in the south west and south.





A not dissimilar scenario on Sunday but the filling low to the west has slipped over Ireland and the associated occlusion will continue to bring showery rain to the south west.and generally temps around average.



Monday finds the block continuing to be resilient to the energy from the west so once again a rather diffuse analysis with the UK in a very slack gradient which portends another sunny day with some showers with temps around average, perhaps a little above.



 
Part 3 (bold text my annotation):
The GEFS 3-8 anomaly this morning gives a pretty good overview of the above.

The key players, the Hudson Bay vortex/lobe, the Scandinavian block ridging north west, low pressure over Europe and the Atlantic trying to ridge north east. Thus the westerly upper flow diverging west of the UK leaving the latter virtually in a col.


The ecm (EPS anomalies) quite similar for Saturday and the beginning of next week with slack gradient over the UK portending sunny intervals and showers, perhaps heavy and thundery in places, with temps around average.

 
Malcolm's thoughts for the 19th:
The weekend will be warm and sunny with some exceptions.

Today after a chilly start it will warm up quickly with plenty of sunshine. It may be a little filtered still in north west Scotland where the front is still adjacent and low cloud and mist will still be a feature along the south east coasts so temps down here. As they will be a tad in other coastal areas as the sea breeze kicks in. The low cloud and mist may become more extensive through the evening and overnight which again will be quite cool under clear skies. But by 00 Sunday cloud and rain with a freshening wind will encroach N. Ireland and western Scotland as fronts associated with the low over Iceland track east.





Through Sunday the front tracks a little further south east thus continuing patchy rain with cooler temps and quite breezy in the north west whilst elsewhere the ridge continues to dominate and another warm and sunny day will unfold with the same caveat vis low cloud in the east and sea breezes.



Monday will be another very warm and sunny day for most, the exception being the west of N. Ireland and the Western Isles where the front is still loitering. But changes are afoot to the west. Another cut off upper low has formed west of Iberia, courtesy of renewed ridging north east of the Atlantic high pressure, which invigorates the low pressure to the south which moves north introducing an easterly and perhaps some convective activity.in the south as the ridge is pushed north east.





By Tuesday this has resulted in a high cell north of the UK and with the aforementioned low pressure safely ensconced to the south there is a light easterly over the UK leading to another very warm day, apart from the north of Scotland where the front is still lingering. Still a risk of some thundery outbreaks over central England and Wales.



A not dissimilar story on Wednesday except the high pressure has shifted north east over Scandinavia albeit still maintaining the easterly over the UK and still the possibility of convective activity in the south in what will be another warm and sunny day for everyone.



According to the gfs around now is rather a key time as the upper trough to the south gets a further boost which tends to establish an anticyclonic/low pressure north south split but which will prevail?

 
Malcolm's thoughts for the 20th:
Summary

Fine, warm, and dry but there are exceptions

Currently a band of light rain is across N. Ireland and central Scotland which will not progress much further south east against the block during the day. On the contrary it will move back the way a tad this evening and over night resulting in a substantial accumulation over the western Isles. Elsewhere it's been a clear night apart from the east and south east coasts where low cloud pushed a little inland. also some patchy mist/fog along the south coast. This will generally clear during the day So another very warm day beckons for but cooler where the sea breeze in. The gfs temps are probably under cooked but it does give an idea of the range.







So tomorrow continuing wet over the north west although it may slowly clear later and once the low cloud has cleared the east anther very warm day with the chance of thundery showers developing in central/southern areas, and the usual caveat vis sea breezes and of course across N. Ireland and the north west of Scotland where the front and rain severely depresses the temps.





But a key move on Monday vis the overall evolution is the high pressure once again amplifying north east creating another cut off low that slips south east towards the low pressure in the western Mediterranean



On Tuesday the result of all of this sees a new surface high cell north of Scotland with a broad area of low pressure to the south thus an easterly regime over the UK which will bring cooler temps the east coast and perhaps some mist/low cloud whilst elsewhere will have another warm and sunny day with a continuing risk of thunderstorms in southern areas.



A very similar story over the next two days as the high cell relocates over Scandinavia and the area of low pressure persists to the south with the continuing risk of thundery outbreaks in the south and west



 
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