Storm Forecast
Valid: Thu 29 Sep 2011 06:00 to Fri 30 Sep 2011 06:00 UTC
Issued: Wed 28 Sep 2011 14:55
Forecaster: GATZEN

A level 1 was issued for northern Algeria and Tunisia mainly for large hail and excessive rain.

SYNOPSIS

High pressure dominates central Europe, whereas a trough amplifies over east Europe and will affect the Black Sea region. Weak geopotential is also present over the Mediterranean. Given the weak diurnal heating depending on the season, CAPE is absent over most places except for the Mediterranean.

DISCUSSION

South-west Mediterranean and Atlas mountains

Rich low-level moisture is indicated by latest soundings over the west Mediterranean Sea. Given relatively cold mid-level air, neutral to unstable lapse rates have developed. CAPE in the order of 500 J/kg is expected over a rather broad region. Low-level forcing is limited and will be best at night when land-sea-circulations will lead to low-level convergences. Scattered thunderstorms are forecast capable of producing locally excessive rain.

Along the boarders of Algeria models agree about favourably veering profiles. Low-level winds will likely turn northward during the day, while the wind will turn from easterly directions at 850 hPa to westerly at mid-levels. Supercells may develop capable of producing large hail and excessive rain.