Storm Forecast
Valid: Fri 02 Apr 2010 06:00 to Sat 03 Apr 2010 06:00 UTC
Issued: Thu 01 Apr 2010 19:46
Forecaster: TUSCHY

SYNOPSIS and DISCUSSION

Near neutral NAO conditions are present during the forecast with low geopotential heights over most parts of Europe as extensive cyclonic vortex persists over / north of UK/Scotland. Weak geopotential height gradients persist over the Mediterranean and E-Europe with cool mid-levels atop regionally better BL moisture, enhancing the thundersorm probabilities over certain areas, mainly SE-Europe and S-Norway/Sweden. Shear/instability remains weak at best, but an isolated large hail event over Bulgaria can't be ruled out. However, there is no indication of anything more organized, so no level will be issued.

A cold front crosses UK and NW/N-France during the daytime hours from west to east with a classic postfrontal shower/thunderstorm set-up. A plume of well mixed maritime air and temporarily diabatic heating support adequate updraft strength during peak time heating for showers/thunderstorms. Marginal hail and strong wind gusts accompany those storms with the first risk probably being the more dominant one, given the lowering WBZ level. An isolated waterspout/tornado may develop mainly along the S/SW coast of UK, as LL lapse rates increase somewhat, but there are no indications for a more elvated tornado risk. Onshore activity diminishes after sunset with ongoing activity offshore (e.g. the English Channel). A large thunderstorm area may be the best choice with such a pattern and during a season, where insolation may assist in initiation over various places. Isolated thunderstorms may occur well to the east of the highlighted area over central France, but coverage will be negligible.

Some models indicate a low-end chance for isolated thunderstorms over parts of the Alps, but recent snowfall and mostly snow covered mountains may suppress heating/anabatic winds enough to stick with no thunderstorm area.