First and foremost, on this day back in 2003 we set a new UK all-time record high of 38.5C at Faversham, Kent. Scotland also witnessed it’s hottest day with 32.9C at Greycrook.

Today is quite different beneath a fresh northwest air flow. Following a new summer minimum of -1C last night at Dalwhinnie, it’s a cool and increasingly wet day across Scotland while showery further south. Temperatures 2-3C off the seasonal average for August 10th.

We’ll have a hard time reaching 20C even in London this afternoon and beneath the cloud and rain streaming in off the Atlantic, parts of Argyll, Lochaber and NW Highlands may struggle to see 12C.

A strong Azores high positioned SW of Ireland will nudge east allowing warmer air back in across the southern British Isles, however a low drifting in between Greenland and Iceland is drawing on moisture from the warmer subtropical waters of the Atlantic to the south. As this moisture lifts up, it’s channelled in the upper steering flow between low and high into Scotland. This will present a multiday flooding rain event to Western Scotland.

The below GFS sea level pressure chart displays the situation nicely.

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A wave running the westerly flow will enhance the rainfall for NW Scotland, enhanced further by orographic influence.

The leading edge of that moisture plume with subtropical origin is currently spreading into Western Scotland.

The GFS precipitation chart from now through Friday shows the persistent and heavy nature of this rain, particularly for the west facing slopes of the Northwest Highlands.

Heat surge arrives

As we progress through this weekend, secondary low departs Canada and heads into the North Atlantic and deepens into a significant storm system. It’s this feature that will help pump heat and humidity north over ALL of the UK Sunday through Tuesday of next week. As the trough deepens in the North Atlantic, so the high shifts east allowing a nice south to southeast aire flow to develop and draw on some very warm, humid air. Low 30s for southern England and mid perhaps upper 20s for Scotland is possible.

Midweek breakdown

That very low which helps give, will take away towards mid next week as another low forms at the base of the trough over the Atlantic. That lows lifts in over Ireland and breaks the heat and humidity with thunderstorms.

See today’s video.

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