Thursday 29th January
Wednesday gave us the first totally dry day since the 17th and only the sixth dry day this month. The welcome sunshine eventually dispersed the valley radiation fog that had become widespread by 08.00 and cleared by 09.30, raising the temperature to a peak of 8.4C by 14.29 being 1.3C above average. The cloud cover overnight was variable but there were sufficient breaks to allow the temperature to drop to a low of 1.1C in the very early hours at 00.06, being 0.1C below average. An indication that although we are under mainly cloudy conditions, the light, when the sky is clear, is getting slowly stronger, as yesterday the high solar radiation was the highest since 13th November with 410 W/m2 at its peak, logged at 12.01.
First light on Thursday revealed very misty, in fact foggy conditions, that limited visibility to around 400m. The temperature had risen a fraction to read 1.7C at 08.00. With thick cloud likely to dominate our weather today and relatively high humidity, it will be a cooler and duller day.
The high temperature contrast over America is still driving a powerful jet stream across the Atlantic hustling depressions towards the UK. The forecast in the next twenty-four hours will see a total of five centres of low pressure surrounding the UK. By tonight two warm fronts with arrive and traverse the UK producing yet more rain, there will be several hours starting during the evening, heavier towards midnight. Yet more yellow warnings for rain have been issued, however, they are just to the west of or area.
The powerful jet stream is intensifying ares of low pressure moving towards us, pulling in warm, moist air from the Atlantic, which in turn ramps up the strong winds, heavy rain and stormy conditions.
The jet stream doesn’t necessarily create more low-pressure systems; it supercharges them, making them faster and stronger.
In a nutshell, the stark temperature contrast north to south across the USA supercharges the jet stream, which has the effect of ‘bigger weather’ here in the UK; wetter, winder and wilder than it would otherwise be.