Storm Forecast
Valid: Sat 02 Jun 2012 06:00 to Sun 03 Jun 2012 06:00 UTC
Issued: Sat 02 Jun 2012 06:03
Forecaster: SCHLENCZEK
A level 2 was issued for central Francde mainly for large to very large hail and to a lesser extent for excessive precipitation and severe wind gusts.
A level 1 surrounds the level 2 for large hail, excessive precipitation and severe wind gusts.
A level 1 was issued for the N Maghreb States mainly for large hail and severe wind gusts.
SYNOPSIS
A hot and moist airmass from Iberia is advected northwards. As the environment of this plume of very unstable air becomes more baroclinic, deep layer shear also increases. The focus for severe convective storms in Europe on Saturday will be central France.
Other regions with some possibly severe convection in a subtropical airmass are the N Maghreb States, Iberia and N Italy.
In the vicinity of a strong cyclonic vortex centered over the N Baltic Sea, some cold air convection is expected. It is not very likely that storms will profit from locally augmented deep layer shear and some LL shear and might produce a tornado.
DISCUSSION
...France and Iberia...
Moderate to high instability is expected with the hot airmass which overspreads S and central France during the day. GFS indicates some 1-2 kJ/kg MLCAPE partly overlapping with 15 - 20 m/s of 0-6 km deep layer shear which will create favourable conditions for severe multicellular and supercellular storms. Any storm that evolves in such an environment should be capable of producing large to very large hail. Severe wind gusts and local flooding are possible as well, given a steep vertical gradient of Theta-E and a high amount of effective PWAT.
Further south and west, instability is somewhat lower which reduces the chance of very large hail. This area is covered by a level 1.
...N Maghreb States...
Moderate MLCAPE due to an EML and a moist boundary layer combined with 10 - 15 m/s of 0-6 km shear may allow some isolated multicellular storms and maybe also a few supercells which may produce isolated large hail and severe wind gusts. As also seen the day before, clustering is not very likely and therefore a level 1 is issued as the hail/ wind gust threat will persist throughout the whole afternoon and evening.
...NE Poland, Lithuania, Belarus...
Only marginal instability is expected with the cold front and upper trough of the developing low pressure system over the Baltic Sea. Nevertheless, locally strong 0-1 km shear and SRH1 in order of 150 mē/sē may allow an isolated tornado event. No threat level is issued as the probability of such an event is too low.
