Storm Forecast
Valid: Wed 28 Apr 2010 06:00 to Thu 29 Apr 2010 06:00 UTC
Issued: Tue 27 Apr 2010 19:48
Forecaster: KOROSEC

SYNOPSIS

An omega like ridge pattern with large high pressure area builds over Europe. On its eastern side, weak geopetential falls within the large but weak upper low will persist and will be moving southwards into SE Europe. On the western side of the ridge, a large trough with an attendant surface front digs into western Europe and Iberian Peninsula.

DISCUSSION

... NW Iberian Peninsula ...

Ahead of an approaching trough/front, moist and warmer airmass advects across the Iberian Peninsula. It seems that destabilization is likely in the afternoon hours as the mid-level lapse rates become steeper. Both QG forcing ahead of the trough and strong diurnal heating should be enough to overcome the weak capping inversion and convective initiation is likely just ahead and along the surface convergence/cold front. About 500-800 J/kg of MLCAPE seem reasonable to release and overlap with moderate deep layer shear in range of 15-25m/s. Therefore, some organized multicells or even supercells can be expected with the main threat for large hail and strong wind gusts.

Due to simulated quite limited coverage of convective activity on today's model runs, a severe threat level has not been issued at this moment. But situation will be closely monitored for a possible upgrade tomorrow if coverage will be more widespread than currently anticipated.

...highlighted areas in southern Italy, the central Balkans and eastern Europe...

Some areas will again see mostly diurnal driven convective activity as cold mid-levels still persist within the large but constantly weakening upper-level depression. Still healthy BL moisture and good temperature insolation should yield several hundreds J/kg of MLCAPE and locally, again most likely along the complex terrain, showers and thunderstorms will initiate. The strongest cells could pose a threat for marginally large hail and intense convective rainfalls due to weak wind profiles and mostly pulsating nature convective cells.