UK Weather Advisory
Issued: 12:30 12th June 15
Valid Until: 09:00 13th June 15
Elements: Heavy Showers and Rain, Thunderstorms, Localised Flooding
Has we have been forecasting and discussing for some time the combination of high temperatures and humidity today with increasingly unsettled conditions will lead to the risk of some potentially severe weather during the latter stages of Friday and overnight into Saturday. Showers and longer spells of rain will develop across parts of Wales and SW England during Friday afternoon and into Friday evening with some locally very heavy rain possible of which may bring some localised travel disruption and poor driving conditions during the evening rush hour period. Further east, across more central and southern areas of England, there is a risk of some isolated or scattered severe thunderstorms developing into Friday evening as well. These will be ‘hit and miss’ as usual and not everywhere will see them, but where they do develop then some localised severe weather is possible due to the risk of torrential rainfall leading to possible surface water flooding, hail and lightning.
As Friday evening and the first part of Friday night progresses a more organised region of heavy showers and longer spells of rain will develop across Wales and the Midlands and then slowly move northwards into N England. Some further localised thunderstorms remain possible into the overnight period, but generally the risk of thunderstorms will ease into Friday night and with just a region of moderate and heavy rain potentially leading to some large rainfall totals and some localised surface water flooding.
At the moment, given latest higher resolution model data, it will be parts of Wales and SW England that see the largest rainfall totals through the next 12 to 18 hours or so with perhaps up to 30mm to 40mm rain possibly falling within quite a short period of time. Equally if the isolated or scattered thunderstorms develop across more central and southern areas of England then these too could produce similar rainfall totals but clearly on a very localised scale. The more organised region of rain that will develop and move northwards into Wales, the Midlands and N England overnight will generally produce 10mm to 20mm of rainfall quite widely but with locally higher totals.
The advisory graphic below highlights a broader area at risk of potential severe weather in yellow through the advisory period, but the amber region is the primary region at risk of severe weather due to thunderstorms and longer spells of heavy rain.
Chief Forecaster: MH