Further Wind & Rain To Come This Week. Flooding Will Worsen Before Easing
The flooding situation, caused by relentless spells of rain since since early December, has become increasingly serious over the weekend across southern England. Now there are 14 Severe Flood Warnings for the Thames in Berkshire and Surrey and 2 for the Somerset Levels this Sunday evening - these warnings are for severe flooding and danger to life. Not to mention the 158 Flood Warnings in places across England and Wales, most of them across SE England, The Midlands and SW England.
So a new week arrives, but the rain and wind problem won't go away, with another week of low pressure systems rolling in off the Atlantic, unleasing yet more rain, strong winds and even snow across the UK. It's been a rather windy weekend, with gusts in excess of 80 mph across SW Wales and a further 20-40mm of rain in southern areas. The winds are easing now and the rain in the form of showers are now confined to the west. Monday should see a drier day for most away from rain across the far southeast and showers in the north, with winds lighter and more sunshine in store for many.
But another area of low pressure approaches the NW of Britain Monday night into Tuesday, which will spread a band of rain and strong winds east across all areas, bringing a further 10-20mm widely, with 30mm+ possible across the higher parts of SW England and south Wales. With little time for watercourses to drain the rainfall of the last few days, this is not good news. Although rain will be the main concern, colder air surging east across the Atlantic directly from NE Canada will turn the band of rain to snow on its western edge - more particulary across higher ground of north Wales, Northern England and Scotland - where we could see 5-10cm settle above 200-300m, but we could see wet snow falling at lower levels across central and northern Britain too. Winds won't be a great issue inland as this weather system passes through on Tuesday, but we could see the south to southwesterly wind ahead of the frontal system gust to 50-60mph around southern and western coasts Tuesday morning.
A cold and strong polar maritime westerly flow looks to follow the frontal system bringing rain and snow clearing the east coast Tuesday afternoon, with wintry showers moving in from the west, bringing further snow to high ground across the north. Barely 24 hours after Tuesday's band of rain and strong winds clears, the next Atlantic system rolls in hot on its heels. A deepening low pressure system looks to move northeast across Ireland on Wednesday, reaching Scotland by midnight, bringing another spell of rain (10-20mm) east across all areas in the evening. Winds look to be an issue too with this system, with gusts of 60-70mph indicated for southern Britain, even inland, perhaps up to 80mph along southern and western coasts. With cold air in place across northern areas and more cold air coming in from the west behind this system, we are likely to see further significant snowfall higher parts across Ireland, northern England and Scotland - with snow falling and settling perhaps even to lower levels for a time Wednesday night.
There is some uncertainty from model output for later in the week, ECMWF indicates a west to southwest flow with further spells of rain or showers across southern England and NW Britain on Thursday, otherwise dry elsewhere. GFS brings in another low across southern England bringing rain and hill snow across southern England, while drier further north. UKMO brings the low a little further north, bringing rain east across southern and central parts. Wind not an issue on GFS - with strong winds over France, UKMO more an issue with winds with a deeper system and further north.
However, GFS, ECM and UKMO do all bring aother low pressure system northeast somewhere across England and Wales Friday night into Saturday morning, GFS worryingly developmental with the low deepening rapidly across Sern Britain, ECM and UKMO less so with a shallow low. All would bring alot of rain again, whatever the depth.
GFS accumulation charts are indicating 50-60mm across southern counties of England, south and west Wales over the next 7 days - so I regret to say, the flooding is likely to get worse before it gets better.
Beyond this coming week, there are indications from the models of more amplitude in the flow developing across the Atlantic, which may mean the Atlantic storms finally ease and we could even see high pressure build across southern areas, at least for a few days, which would bring a break from the rain and allow rivers to empty and floods to subside. These are only tentative signs and are thus not a guarantee of an end in sight.