CONVECTIVE FORECAST
VALID 06Z THU 04/11 - 06Z FRI 05/11 2004
ISSUED: 03/11 21:37Z
FORECASTER: GATZEN

There is a slight risk of severe thunderstorms forecast across southeastern Mediterranean

General thunderstorms are forecast across Iberian Peninsula, Mediterranean, northwestern Europe

SYNOPSIS

Long-wave ridge placed over eastern Europe, while upper trough is present over northwestern Europe. Two cut-off lows are expected to affect the Iberian Peninsula and the southern Mediterranean. Warm and unstable airmass remains over the central and southeastern Mediterranean.

DISCUSSION

...Southeastern and central Mediterranean ...
Warm and unstable airmass will remain over the Mediterranean to the east and north of a cold front moving eastward over southern Mediterranean. This airmass is characterized by rather rich low-level moisture and stepp lapse rates aloft, creating CAPE values in the order of several hundred J/kg over the central Mediterranean and up to more than 1000 J/kg over southeastern Mediterranean. On Thursday ... synoptic forcing is expected at the eastern flank of propagating upper cut-off low ... and thunderstorms should go on over southeastern Mediterranean. 20+ m/s deep layer wind shear will be present and organized convection is expected. Supercells should be possible capable of producing large hail and severe wind gusts as well a few tornadoes due to low LCL heights in the range of the cold front. Over central Mediterranean ... vertical wind shear will be weak ... and organized convection is not likely. However ... modified low-level vertical windshear near coastal regions may be sufficient for a mesocyclone or two ... and one or two tornadoes are forecast.

...NWrn Europe ...
In the range of the upper trough ... well mixed maritime airmass will destabilize during the forecast period ... and thunderstorms are expected. Increasing deep vertical wind shear may be sufficient for isolated severe convection ... capable of producing severe wind gusts and a tornado or two.

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