After the flooding, a cold northerly flow before an Atlantic low arrives

What a lot of rain. Social media feeds have been full of scenes showing deep wide water across major roads in Bedfordshire and that unfortunate car boot, along with the high street flooding in Dunstable. The past few days have presented lashing rain, hail and thunderstorms, frequent lightning, and significant surface water flooding. 

Tuesday morning National Highways EAST “The A421 Bedfordshire remains closed in both directions between A6 Bedford and M1 Brogborough due to flooding following heavy rainfall. Our area team continues to work at the scene taking water away using tankers.”

There has been over 100mm of rain in places. Think about all that concrete and soil sealing, where would all the water flow to or be stored? Overwhelming drains as well. Vienna was recently hit hard by Storm Boris but has crucial flood management schemes with overland canals and underground tunnels. Trees, parks and green spaces are important. 

“it is the UK's turn to experience serious flooding due to intense rainfall. A reminder that UK rainfall intensity has increased markedly over the past 60+ years. All consistent with the physics of a warming atmosphere which is now more humid.” Ed Hawkins

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Woburn in Bedfordshire had its wettest day on record on Monday seeing more than twice the average rainfall for September. The Environment Agency and local councils will continue the clear-up, but Tuesday does look drier for the flood-affected areas with the low pressure now clearing off over the North Sea to Denmark. 

As the low pulls away a colder northerly flow tucks in, following a weather front over northern Scotland. This cold front will push rain against the Grampians and into Lothian as the chilly wind picks up. South of a line from The Wash across to Pembrokeshire there will be a light easterly breeze, a good deal of cloud but a dry afternoon as the last of the lingering rain fades. For the rest of Wales, northern Britain and Northern Ireland, there will be bright spells and scattered showers. Temperatures in England will be around 14 to 18C today.

The showery outbreaks along the fading front become more scattered as they reach Liverpool across to Whitby and the colder air follows. It will be cold in the north with a touch of frost in rural spots. Showers will appear over southwest England edging towards Cardiff overnight.

Later on Wednesday the Atlantic low pressure will move over the Irish Sea and remain close to southern Britain until Friday. 

The UKV forecast 24 hour rainfall totals for Thursday and next Met Office weather warning, for Rain

Midweek wind and rain

There has been a strong signal on the forecast models showing this incoming Atlantic low pressure with strong winds and heavy rain but lower confidence about the regions of Britain that would be affected. The main frontal rain looks to reach over SW Britain later on Wednesday. Into Wales, the Midlands and northern England during Wednesday evening and northwards into southern Scotland overnight. The cold front will follow with more heavy rain in Cornwall across to Norfolk on Thursday morning as heavy rain curls over Northern Ireland and more of northern Britain. The ECM Model takes the rain over the southern half of Scotland but the UKV just brushes the border. Winds will rotate around the low but northern England looks windy and wet in places on Thursday. Southern parts could reach 16 to 18C but Scotland and Northern Ireland will be around 11C.

The Weekend

As the rain sinks southwards, the cold northerly winds dig in on Friday with the chance of frost in the north for Friday night. As the low heads away towards the Alps, high pressure will build in from the southwest settling our UK weather for Saturday. There are differing solutions for the start of the new week. The ECM Model showers a lively Atlantic low pressure heading for Ireland later on Sunday. This one looks lively with potentially gale-force winds by Monday morning. Other models keep the high pressure nearby and a more settled outlook.