Storm Forecast
Valid: Sat 27 Feb 2016 06:00 to Sun 28 Feb 2016 06:00 UTC
Issued: Fri 26 Feb 2016 21:58
Forecaster: TASZAREK

A level 1 was issued for E Sardinia, E Corsica and W Tyrrhenian Sea mainly for the severe wind gusts and in lesser extent for large hail.

A level 1 was issued for NE part of Spain mainly for the excessive precipitation.

SYNOPSIS and DISCUSSION

A large mid-level low with cold air of polar origin sinks southeastwardly to W Mediterranean and increases thermodynamic instability mainly over the marine areas. A polar jet stream stretches from N Atlantic through NW Africa, up to CNTRL Mediterranean where it weakens. A minor trough is placed over N Scandinavia and provides northwesterly flow along Norwegian coast where an isolated lightning is possible. A considerably higher lightning threat falls on W Mediterranean where thunderstorms are likely within approaching cold front and behind it (cold sector). A boundary layer's moisture content up to 4-6 g/kg and a steepening lapse rates result in a few hundredths of CAPE - mostly in the low sheared environment. The highest threat for the thunderstorms lies over marine areas because of higher boundary layer's temperature. Exception is a NE part of the Spain where a strong QG-lift may support the development of TS over the land surface in the afternoon hours. As with time the trough becomes stationary, a superimposing convective and a large-scale precipitation, pose a threat for the excessive precipitation. Thunderstorms over W Mediterranean basin should go on until late nighttime hours. In the end of the forecast period, an increasing boundary layer's moisture (up to 10 g/kg) converging beneath steep lapse rates (~ 7 C/km), and a secondary signal of PV advection over W Tyrrhenian sea will create a good conditions for the development of longitudinally arranged DMC. Within these storms, a 20 m/s DLS and a favorable vertical moisture profile creates a small threat for the severe wind gusts and a large hail (up to 2 cm). The threat is mostly confined to the marine areas and less likely over Sardinia and Corsica. It should continue in the next day.