Storm Forecast
Valid: Sun 24 Aug 2008 06:00 to Mon 25 Aug 2008 06:00 UTC
Issued: Sat 23 Aug 2008 20:18
Forecaster: DAHL

SYNOPSIS

Rather complex upper flow pattern existing over Europe ... with an upper trough/low over E Europe, attaining an increasingly negative tilt while making some eastward progress. A weaker upper trough will move from the Biscay region into the W Mediterranean. A weakening upper cut-off low is simulated to move from the Balearics to central Italy during the period. Quite intense and large upper cyclone and attandant SFC low are approaching the British Isles from the N Atlantic late in the period. At low levels ... subtropical air is present over the Mediterranean as well as over E Europe while central parts of Europe are dominated by modified polar air masses. SFC cyclogenesis is anticipated ahead of the E European upper trough over Belarus and the N Ukraine late in the period while quiescent SFC conditions prevail over the rest of continental Europe.

DISCUSSION

... E Belarus ... NW Romania ... SW Ukraine ...

Some threat for severe thunderstorms will exist E of the upper low affecting the eastern portions of Europe. CAPE is not expected to be particularly impressive, but sufficient for sustaining deep copnvection. DLS of 15 to 20 m/s suggests that multicellular storms with isolated/imbeeded mesocyclones may occur, capable of marginally severe hail/wind. Isolated tornadoes may also occur especially over north-central Romania and southern Belarus where more 10 m/s LLS are expected.

... E Spain ...

Rather strong CAPE should persist over the extreme W Mediterranean and the E Iberian peninsula. Indications are that thunderstorms will be very isolated, being tied to insolation/orographic forcing. DLS should be on the order of 10 m/s which may suffice to allow for weakly organized multicells capable of marginally severe hail/wind gusts. Storms should diminish after sunset.

... SW Mediterranean ... N Algeria ... N Tunesia ...

Ahead of the small upper low over the W Mediterranean, some instability should persist. Degree of instability is expected to be rather modest given only shallow low-level moisture and weak mean mid-level lapse rates. Still, DLS will be sufficient for organized convection capable of large hail and severe straight-line winds.