Storm Forecast
Valid: Sat 29 May 2010 06:00 to Sun 30 May 2010 06:00 UTC
Issued: Sat 29 May 2010 02:28
Forecaster: VAN DER VELDE

SYNOPSIS

A body of unstable air is present over the southeastern quarter of Europe, including Italy, Hungary, Slovakia, much of the Balkan and Ukraine. Weak high pressure is present over Germany and Poland, France and the Iberian Peninsula. A weak low is present over Scandinavia with the corresponding cold front moving over the Baltic states. Meanwhile, an intensifying low moves from the Atlantic over UK, Benelux, northern France to Germany, and will settle over central Europe the following days.

DISCUSSION

...Hungary, Slovakia region...

Slow storm motion could cause local flash floods, though it may not exceed our excessive rain criterion. The western limit of the thunder area sees decent deep layer shear (10 m/s 0-6 km) and storms will tend to be more clustered than elsewhere. An isolated landspout also is quite likely given strong 0-3 km CAPE (in GFS). Hail of 1-2 cm is likely.

...southern UK, Netherlands...

Very slight instability, probably elevated, could yield some showers possibly with thunder embedded in the warm air advection zone, also during the night. Convective cloud tops could reach -10°C or a bit colder in GFS. Shear and helicity are rather large, but the situation seems too marginal convection-wise to pose a threat.

...northeast Algeria and central Tunisia...

Almost off the map, but will mention that CAPE combines with strong lifting and large SREH values (>300 m²/s²) with potential for supercells (large hail) and large MCS (gusts, sand storms). It appears that SBCAPE is offset to the north and west of SREH and most convection may be elevated and not profit from all the helicity.