The best way I think to describe our week ahead is, classic autumn! The Atlantic is dominant this week with a series of fronts sweeping through. However what’s interesting is the upper level trough dropping down with temperatures cooling considerably. In other words we have increasingly cold air dropping down while fronts bring bands of rain followed in between by squally, chilly showers across Ireland and the British Isles.

Last night saw a front sweep through Northern Ireland, Scotland in Northern England, today it’s leaving N England and heading southeast.

A Wet Night/Monday AM for South

The boundary attached to a 978 mb low centred near Iceland marks the leading edge of a new weather system and often, the weather is either slightly or dramatically different. In this cause, sun with blustery showers follows in behind. This front will drag a persistent and at times heavy rain band SLOWLY across Wales and the Midlands through this afternoon.

Tonight it brings rain, which could be heavy and persistent across Southern England, causing a wet, windy Monday morning commute, including London. Winds will and are turning fresh to strong from a southwest direction.

Here’s the GFS precip chart for tomorrow AM.

Rain totals could mount up over next 5 days

The issue with this pattern is that with a slow moving parent or mean surface low to the between Iceland and Scotland will act like a wheel, spinning fronts into the UK. Following tonight and tomorrow’s soaking across the South of England, blustery showers follow for tomorrow from the Midlands north.

Here’s a look at early on Tuesday. While the current front will take time to push away from the South Coast, the next front with a well organised rain band will arrive into western areas.

That front like the current one will push southeast and bring another soaking to southern areas by early on Wednesday, the rains after weakening slightly on it’s southward journey, may pep up across Southern England. A lot of that is because of the depth of trough coming down on the backside of the front with VERY LOW HEIGHTS showing VERY COLD AIR at 5,000 feet. This energy pushing into a milder atmosphere can ignite bigger rains and this is something we need to watch for especially during the mid week timeframe.

Here’s early Wednesday. Note the HEAVIER rains as the front becomes more potent with the cooling to it’s north.

Here’s the current 500 mb heights for today.

Now look at the 500 mb heights for Wednesday! Note the speed max ripping across the South of England right where the surface front is… That’s why rains could be significant Wednesday AM.

This cold air aloft will be felt in the breeze and with passing, squally showers you’ll notice the temperature dropping, perhaps from 10C to 4-5C within the shower. Could there be sleet mixed in with the rains in the heavier bursts even down to lower levels with snow showers above 1,000 feet? Yes, that’s quite possible during Wednesday, Thursday given the cold air which can get projected downwards when precipitation falls heavily.

First HARD FROST on Wednesday & Thursday night?

Later on Wednesday, isobars will spread out and so winds should ease off and so too should the showers. With this setup and very cold air aloft with a trough positioned directly overhead, we should see a widespread frost and this could be a pretty hard frost with towns and cities dropping below freezing and rural areas falling to between -2 and -6C. Perhaps the first -7 or -8C in the sheltered Highlands?

Here’s the precip chart and below it, the ECMWF 850 temps AT 500mb.

Another batch of heavy rains for South Friday, courtesy of Nadine?

The GFS shows more weather moving into western areas later Thursday as another front swings in from the stubborn low to the north but as Thursday becomes Friday there is interesting info coming out of the model for Southern Britain.

The compact system which can be seen caught in the flow of a much larger low is Hurricane Nadine. The current run of the GFS has this spinning around and up the east side of the more dominant, larger low and appears to head our way.

Interestingly, Friday sees a pulse of heavy rains spreading out of Nadine and spreading across the southern half of Britain. If this scanrio played out. This would certainly bring some tremendous rains and likely flooding. It’s important because this will have already been a very wet week across the South.