Storm Forecast
Valid: Tue 10 Nov 2009 06:00 to Wed 11 Nov 2009 06:00 UTC
Issued: Tue 10 Nov 2009 07:18
Forecaster: VAN DER VELDE

Level 1 and 2 were issued for parts of Greece, Bulgaria and Turkey mainly for tornadoes, gusts and local excessive rain.

A level 1 was issued for the Tyrrhenian Sea and Adriatic Sea for waterspouts.

SYNOPSIS

A low pressure area over Italy and Balkan moves eastward. A cold unstable airmass covers a large area in the central Mediterranean. This area is rounded by a jetstream with 300 hPa winds over 60 m/s, blowing over a frontal zone from Africa into southern Greece and Bulgaria. GFS develops CAPE also in the northern Aegean and surroundings under the axis and exit region of the jet.

DISCUSSION

...Greece, S Bulgaria, NW Turkey...

At the beginning of the period a cold front drags over southern Greece. At this point, CAPE is calculated by the model (GFS) but predicted EL values are still not cold enough. This improves during the afternoon and parameters look favorable for initiation of storms. In range of the jet exit, large upper forcing should be available, and when storms develop in the strong shear environment (30 m/s DLS, >15 m/s LLS, >200 m²/s² SREH3)supports storms with mesocyclones which may produce tornadoes as well as bow echoes with severe wind gusts. Isolated large hail and excessive rain are also possible. The intense moisture transport encountering higher terrain in N Greece could provide a focus for storm development and as well as more continuous stratiform rain.
The activity will shift to western Turkey during the evening and night with mostly the same threats. The best upper forcing should arrive in SW Turkey at the end of this forecast period.

...central Mediterreanean...

Waterspout chances are significant over the Tyrrhenian Sea and southern Adriatic Sea due to good low level buoyancy, superadiabatic lapse rates and weak surface winds and storm motion.