The strong signal for a surge of heat over the weekend has diminished somewhat. It’s still possible and it will feel warmer at the weekend (although that isn’t too difficult with all these showers and the cool westerly flow).
A dominating Atlantic low pressure will slide north of Scotland, from Iceland to Sweden, and hamper the high pressure building over southern Britain. A cooler flow around that low pressure will feed down the North Sea. Although there is still the potential for temperatures to rise into the high twenties Celsius, even passing 30C, confidence is lower. Hopefully the signal will firm up over the next day or so.
Netweather Radar 11:15 showing scattered heavy showers and sferics (coloured dots -lightning strikes), high cloud out west
Eastern Britain and Shetland have seen a fine start to Wednesday with sunshine. Elsewhere, there is more cloud and showers are getting going once more. Later today, it will be eastern counties seeing most of the showers with hefty downpours as they ease off further west. On the radar and satellite image, there is high cloud appearing from the Atlantic, this is a low pressure which will bring wet weather across the UK on Thursday.
It’s another day of bright or sunny spells but then the skies darken and along comes a shower. Again, there will be some heavy, even thundery showers.
“Heavy showers … develop widely through the morning inland, thunderstorms will develop as surface heating steepens low to mid-level lapse rates, greatest CAPE values towards eastern England /eastern Scotland in the afternoon – so here most likely see the greatest risk of thunderstorms while convection eases towards the west. Storms will be generally short-lived given weak vertical shear – though localised E-W aligned breeze convergence zones may organise showers/storms into bands” Convective forecast
Yesterday, a village in Aberdeenshire turned white as a blanket of hail covered streets and gardens. It almost looked like June snowfall at first glance. Temperatures today will be around 14 to 17C but feeling much cooler in the hefty downpours. By early evening, there will still be clusters of showers for eastern Britain but elsewhere the weather will be settling down. With a slight rise in pressure ahead of the incoming low, there will be a calmer lull with drier conditions and clear skies and it will feel cool this evening.
Tonight
Showers will continue in the far north of Scotland as high frontal cloud arrives over Ireland. It will turn wet with a southerly wind for Northern Ireland overnight.
Thursday
Wales will have a wet Thursday with heavy rain over the mountains and for western counties. First thing on Thursday, the frontal rain won’t have reached northern Scotland or Norfolk and Suffolk but there will be blustery wet conditions around the Irish Sea and for SW Britain.
The warmer air from the south will be caught up in the warm sector, so if breaks appear in the cloud cover, temperatures could jump up to 19C or 20C. Southeastern Britain will be wet by lunchtime as the rain eases from Northern Ireland and southwest England, although still with a lot of cloud. Through the day the blustery winds will veer from a southerly to a westerly. The main rainband will move from NW England and western Scotland across more of Scotland into the evening with a wider grey and damp picture. Gaps in the cloud could appear to the lee of high ground and you will feel that warmth in any sunshine.
The occluded front (and rainband) heads north to Shetland as the cold front moves over Britain. This is the main dividing line into the weekend with the very warm air to the south and the cooler air to the north.
Friday will be a more settled, but windy day. There will be sunshine for northern areas, more cloud in the south and a scattering of showers in a brisk westerly wind. It will feel cooler in the northwest but as sunny spells appear over England and Wales, temperatures should move into the high teens and low 20sC.
During Friday night, the low pressure heading towards Scandinavia will steer cooler air down over Britain with blustery showers for Scotland.
Warmer air to the S/SW and cooler air further north. Possible temperatures on Saturday although uncertainty
The Weekend
Then it is a case of push and shove as the high to the south tries to build over southwest Britain, allowing more sunshine, warmer air and temperatures to climb. Whereas the low to the northeast continues to steer the cooler air from the north. Scotland, particularly in the northwest, will have an unsettled Saturday with showers or outbreaks of rain but these should fade by the evening. Elsewhere should be drier over the weekend. Temperatures could be 17 to 26C on Saturday and 18 to perhaps 28C by Sunday.
The main uncertainty is around this boundary between the cooler air to the north/NE and the warmer air from the southwest as it tries to surge north over the UK. Any sunshine will feel very warm and the weekend outlook is drier, after the heavy showers and Thursday rain.
Top image – Bass Rock in the Firth of Forth
