Rain is heavy and persistent over the Northwest UK right now and you can see in the visible satellite imagery below, that cloud and moisture extends way out into the Atlantic with sub-tropical origin. The sub-tropical or southern branch jet stream is at work. The polar jet or northern branch is to the north.

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Water vapour

This stream is not just saturated but warm too. Temps across the board are between 10-13C over the UK today.

Snow melt is causing local flooding in the Highlands. Just look at the difference between Friday morning and now.

This strongly zonal pattern is part of a large-scale hemispheric pattern. We’re seeing the same setup in the Pacific with a deep moisture plume extending from far out in the Pacific which is affecting the North American West Coast. A nice teleconnection.

There’s little change through the first half of the week as the pattern remains stuck with the hose of moisture holding firm, bringing a continuation of today’s deluge. The 5-day rain totals off the QPF says it all.

Look at the similarity on the North American West Coast. This flow is flooding both continents with mild, maritime air.

The reason for the current setup is simple, both the Arctic Oscillation and North Atlantic Oscillation are positive which means all the bitter cold is bottled up over northeast Siberia and the Arctic. See the negatives over Alaska and Greenland with a westerly/zonal flow underneath.

In the 7-10 day we see change as positive heights develop over the very areas there are negatives just now and so these bubbles of high pressure extending north will allow arctic air to come south.

Look at the difference in the height field.

ECMWF 144 hrs

GFS 168 hrs

The next 48-72 hours supports a straight westerly flow with mild, moisture rich air which will really mount of rain totals on west facing upslopes of the UK and Western Europe.

GFS surface

We still see a sharp pattern shift just ahead of Christmas as the stalled frontal boundary sinks south, allowing colder air back in.

Snow showers (if any) will be confined to the North and high ground. Potentially a cold start to Christmas Day with a sharp frost thanks to a clear overnight sky.

The GFS has shown a pretty deep storm centred over southern Britain at the end of the week into next weekend. This may be a snow as well as strong wind producer.

GFS snow forecast

500mb height anomaly positioning looks favourable. This would be a cold one for much of Europe if true.

Finally, the models might now be seeing the onset of an SSWE…

ECMWF EPS

GFS en

Until we see something happen, the wait continues. It’s got to happen eventually…

Some are saying there’s no real cold across the north.

Well it’s near -70F over NE Siberia just now and later down the road, we along with North America may receive air from this region if the above happens.

Will have a new video again tomorrow.

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