The midweek wind and rain forecast continues to bring uncertainty for Thursday. A low centre was forecast to develop along the waving front, which would bring heavy rain and strong, even gale-force winds with high gusts to southern Britain and particularly the English Channel. Today, there seems to be a shift eastwards, taking Cornwall out of the firing line for the gales, but bringing miserable conditions for the evening commute for the M25, London and the Home Counties.
There are two heavy rain warnings over southern Britain. The one for southwest England highlights a very low likelihood of Medium impacts occurring, whereas the warning for southern England shows a higher likelihood of Low impacts. This requires some understanding rather than just looking at the two as plain yellow.
We have the main frontal boundary across the UK with mild air to the southeast. There is colder air to the northwest, which will arrive during Thursday night. We await the returning warm front from the south this morning and the wave along the front. This uncertainty about a deepening low or a more open wave, lowers confidence about the spread of the heavy rain and how high the totals will be and if there will be a core of gales and high gusts. The warm sector will bring mild air, lifting the temperatures to around 10 to 13C for parts of England. Temperatures will be closer to average for the rest of the UK today.
Rain
Southwestern upslopes will see large rainfall totals, in south Wales and the moors of SW England. There has already been a good amount of rain so this will only add to the puddles as 20 to 50mm of rain falls today. The Met Office warning continues from Wedensday adn throughout Thursday as the first signs of heavy rain appear on the radar.
Northwestern Scotland has seen a rash of showers through the night. The trough line will edge away northeastwards as another frontal band extends from western Ireland. There have been lightning strikes along this today, although it hasn’t moved much. By Thursday night, it will have swept across the UK. This line running north-south will bring sudden heavy rain, with gusty winds as it edges over Northern Ireland this afternoon and into western Scotland this evening. Another pulse looks to run up the Irish Sea into SW Scotland heading for Glasgow this afternoon. The western band shows signs of line convection for Wales and western England by the evening on the UKV, so again there could be sudden, difficult conditions on the roads.
The ECM model takes the main rain from SW England, over much of southern and central Britain, missing western Wales, though. Away from North Yorkshire this evening.
The GFS model takes more rain over southern England this morning but misses much of Wales. The southeast of Wales, including Cardiff and for the West Country and the Midlands it will be a wet afternoon with slower progress away from eastern England.
Some parts of northern Britain will escape this rain. Northeastern Scotland (which could do with some rain) will see sunshine and other parts could miss the rain band from the west and the main rain area which will edge away over the North Sea.
Wind
The GFS takes a core of high gusts near the Channel Islands this afternoon, to the Isle of Wight and then across southeastern England this evening. The Arpege model is a bit slower but brings gales over the Brest Peninsula, where Météo France is warning of strong winds, heavy rain, flooding and coastal inundation. The gales and high gusts move across the Channel later in the afternoon with inland windy weather for southeast England and East Anglia in the evening.
Channel ferry crossings will be quite lively this afternoon and the Channel Islands shipping area has an orange wind warning with an F8 gale.
Through Thursday night, there is a trend eastwards of the frontal bands but also some of the rain reaching northwards to the Northern Isles overnight. Colder air will follow as the night becomes drier and clearer until heavy showers appear from the west, ready to interrupt the sunny Friday.
