Storm Forecast
Valid: Sat 24 Sep 2016 06:00 to Sun 25 Sep 2016 06:00 UTC
Issued: Sat 24 Sep 2016 02:28
Forecaster: TASZAREK

A level 1 was issued for Ireland mainly for severe wind gusts.

A level 1 was issued for N Tunisia and N Algieria mainly for large hail, severe wind gusts and in lesser extent for excessive precipitation.

SYNOPSIS and DISCUSSION

A blocking 1020 hPa high pattern covers CNTRL Europe, Balkan Peninsula, W and CNTRL Mediterranean. Low is centred over N Finland. Another low over E Ukraine is cutting off from the wave. A long-wave trough with strong horizontal pressure gradient and low dropping to 980 hPa approaches British Isles. Jet streak stretches from waters SW of British Isles up to W Scandinavia.

Single to multicell thunderstorms in low to moderate DLS and CAPE are possible within enhanced lapse rates and boundary layer moisture in the W Mediterranean basin. A favourable local overlap of 15-20 m/s DLS and 1000-1500 J/kg CAPE along Algierian and Tunisian coast create conditions for the development of multicell clusters and supercells capable of producing large hail and severe wind gusts. Thanks to PVA lobes and diurnal heating, CI should take place in the afternoon hours and within PW exceeding 30 mm may pose a local threat of excessive precipitation, especially over Tunisia where overlap is the most favourable. Single to multicell thunderstorms are also possible on the E flank of the ridge (E Poland, W Ukraine, SE Belarus) where a shortwave trough and frontal boundary passes. Chances for severe thunderstorms exist in NW Europe where within marginal instability, dynamic air flow with MLS up to 15-20 m/s and frontal lift factor, convection may organise into linear segments capable of producing severe wind gusts.