Storm Forecast
Valid: Sat 24 Nov 2012 06:00 to Sun 25 Nov 2012 06:00 UTC
Issued: Fri 23 Nov 2012 22:52
Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

A low pressure area moves from the Bay of Biscay to the NE and crosses S-UK during the overnight hours. Placed beneath a coupled high-level jet configuration, constant strengthening of this feature is likely and even a transient warm-seclusion event may occur during the forecast period. This might insert some uncertainties regarding the final strengthening trend as this one will be a compact system with a chance of rapid pressure fluctuations. Also, with deep WAA forecast, only weak MUCAPE evolves which might induce convectively enhanced rainfall amounts beneath the deformation zone (interesting for those areas, already affected by flooding). However no DMC or electrified convection is expected right now. In addition, we monitor the eastward movement of dry high-tropospheric air towards the back-bent occlusion during the night, which could increase the overall severe wind gust risk (e.g. SE UK during the night). We will watch the area between the occlusion and the backside of the cold front/or triple point for enhanced DMC chances, which would mix severe wind gusts down to the surface.

For the rest of Europe, a quiet November day will be in store (in respect of thunderstorm development). Only W/SW Portugal may see an heavy rain risk with repeatedly onshore moving showers and isolated thunderstorms. The risk remains below our level 1 threshold. I also do not want to exclude an isolated spout event with gradually increasing LL CAPE.