This week will be by far the UK’s wettest in many months and most turbulent since possibly all the way back to February.

This highly active pattern with moisture plume seen in infrared extending all the way back to the Gulf of Mexico is all thanks to a strengthening +NAO induced trough digging down over the North Atlantic increasing the thermal gradient, jet stream, baroclinicity and cyclogenesis.

Check out the warm waters this long fetch moisture stream is originating from. Warm water releases greater volume of water vapour into the atmosphere, hence bigger rainfall when tropics or subtropics are involved.

500mb height anomaly (note trough extends down over warm water!

+NAO typically means Greenland turns frigid beneath a cold high while Europe is mild, settled under a warm high. In between, a lot of rain falls and the boundary extends from tropical Atlantic to UK.

Clear, very cold at Summit Camp, Greenland. Currently -47C (-53F).

East of approaching lows, it can turn unusually warm and yesterday was a classic example with St Jean de Luz, France reaching 28C in the sunshine. Incredible for November.

Europe maximum temps and anomaly yesterday. Note the exceptional warmth over western mainland Europe, AHEAD of the approaching cold front bringing the rains today!

Same low which brought the heat to mainland Europe has dropped over 4 inches of rain in the Cumbrian Fells through the past 24 hours while winds have gusted to 112 mph over Cairngorm in the Highlands.

SSW winds continue to drive moisture into the western UK upslopes but check out the rain shadow effect further east, created by Cairngorm, Grampian and Pennines this afternoon.

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The incubation region this week is way out over the central Atlantic at the base of the cold trough that extends down into the subtropics from north of Greenland. Cold air over warm water is the perfect breeding ground for upward motion and cyclogenesis and with a cross Atlantic jet racing straight across Ireland and the UK at over 200 mph, depressions quickly form and hit in quick succession.

The two strongest jet streaks globally at this time is over the central N Pacific and northeast Atlantic into UK.

Atlantic view

160+ knot jet is crossing the Northern Isles/Faroes today.

Atlantic surface chart shows the broader picture. Note towards day 5 through 7 how the high over Canada lifts up into Greenland!

Total accumulated rainfall next 7 days. Plume very noticeable from tropical west Atlantic to UK.

Similar Pattern To November 2009

This setup was seen back in November 2009 when the subtropics were plugged as big dips in the jet down over the Atlantic tend to allow mid-latitude features to collect greater amounts of moisture and energy and drive it NNE in the form of one wave after another streaming right into the west facing upslopes of the UK. Rain totals quickly build and flooding becomes an increasing problem. his highly active setup will drive a parade of depressions across the UK over the next 5-7 days, likely leading to some quite significant flooding in areas.

As you can see, the GFS shows a 180+knot (200mph) jet crossing the UK.

Within a 2 day stretch (late Saturday through Tuesday), we will see 3 systems impact and by Friday, as many as 5 separate systems running the conveyor will have crossed the UK. Winds overnight last night into today have been strong affecting road travel quite a bit. Low level gusts of up to 60 mph have been reported but in exposed coastal areas of the NW, gusts have reached 80 mph with a 112 mph gust clocked on Cairngorm. Models show Thursday into Friday rather stormy again with gusts to 80 mph likely on exposed Scottish coasts. Gales expected quite widely.

GFS surface.

System 1 (yesterday)

System 2 (today)

System 3 (moves in later today)

System 4

System 5

Rain totals will mount up through the week and by this time next Sunday, parts of the western upslopes of the Highlands, Southern Uplands, Cumbrian Fells, Snowdonia may wind up with as much as 7 inches of rain.

See this afternoon’s video for the discussion.

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Tags: jet stream, november storm, uk flood, uk flooding, uk rain, UK Storm