UK meteorology

Malcolm's thoughts part 1:
The outlook is for it to become very warm/hot and humid in SE/E regions whilst the NW/W is cloudier and cooler with some patchy rain/drizzle at times. This regional split is symptomatic of the slight adjustments to the pattern and may, as it slowly evolves, become more W/E It's all rather knife edgy.





It has been cloudy in many places overnight





And this patchy cloud is likely through the day but in areas with clear periods it will get quite warm in the light winds. Might be the odd shower in the north of England and southern and east Scotland. But through the evening some cloud and patchy rain will effect north west Scotland courtesy of fronts associated with a low east of Iceland.








The fronts and associated cloud and rain will push east overnight Thursday through Friday into the rest of Scotland, N. England, Wales and the west Midlands but all the time weakening against the ridge whilst the south east becomes increasingly humid and warm. This could well trigger some storms, particular along the convergence line.








 
Part 2:
Saturday sees the regional split developing as the weakening fronts stall the south and east become very humid and warm with perhaps the odd shower and relatively cooler elsewhere.








Sunday another warm day but another frontal system will bring some stronger winds and patchy rain to N. Ireland and western Scotland.





A not dissimilar story on Monday but a wave does start to form on the front establishing a more obvious delineation between the NW and SE where it becomes very warm


 
Beyond the limits of the short-range discussion in which Malcolm posts, the extreme heat has eased in the models this morning (though they could revert to the 36-39C range they showed yesterday). At present, the south-east should be around 30C by mid-week, with temperatures dropping-off sharply the further north and west you head and rain or showers in some north-western areas. Late next week into the final weekend of July, the current model runs suggest 35-36 in the south-east and more areas, even to the north-west being in the mid-high twenties.
 
Malcolm's thoughts part 1 (when he mentions det. runs, he means the usual deterministic models that I usualluy refer to - GFS, UKMO and ECM):
Just a brief look at last night's medium term anomalies just to keep abreast of the long wave upper pattern within which the det. runs are operating.


The main players remain the vortex over NW Greenland/N. Canada with associated troughs down through northern Russia and the other south through Greenland into mid Atlantic.Downstream to the latter is the continuing and very impressive block over eastern and northern Europe ably supported by low pressure to the south east.


With the centre of the high pressure temporarily a tad further east the main upper flow backs a little to the south west in the eastern Atlantic and over the north of the UK leaving the south in a much more slack, low pressure area,


This portends a N/S s[lit with some quite variable regional temps and weather albeit the former still above average, but particularly so in the south and east. This is of course where the det. runs come in to sort the detail





Back to the here and now and very much a NW/SE split today with the fronts and rain that were over N. Ireland and Scotland at 0300





tracking slowly south east during the day with the rain becoming quite patchy as the progress of the fronts becomes quite problematic.Meanwhile skies to the east and south of this remain clear and temps rise sharply which will trigger some storms in these areas. If you happen to catch one the rain could be quite intense for a brief period. Both the rain and storms will tend to fizzle out by late evening.


 
Part 2:












Cloud could well linger in western areas overnight and into Saturday but should burn off to some extent as the day progresses whilst again further to the the east temps will rise quite sharply once again and with the increasing humidity this could once more could trigger the odd storm





Sunday sees the upper trough to the NW developing and surface fronts bringing cloud and some patchy rain to the north west whilst in the south and east of England it will be hot and sticky with maybe the odd shower littered around.








On Monday not a huge change to this scenario except a more marked delineation between the NW and SE with the latter becoming hot. whilst the former still under cloud and patchy rain.








A similar story on Tuesday with upper trough established to the west (where we came in earlier) with the very sharp NW/SE delineation continuing.





 
Part 3:
One other quick point. I posted briefly last evening about the ecm and a fragment being ejected from the vortex lobe into southern Greenland where it develops and becomes absorbed in the main Atlantic trough and how this develops is of some importance. Well the same applies to the gfs this morning.


 
Well looks like I'm on the hot side of the line, which is nice.
I think the precise positioning of the fronts which will separate the two airmasses next week is, as yet uncertain. We're not even sure whether my area is going to see storms this afternoon or not, though this sort of scenario is one of the most difficult for even the short-range high-resolution models like the AROME and ARPERGE to determine.
 
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