Storm Forecast
Valid: Thu 19 Oct 2006 07:00 to Fri 20 Oct 2006 06:00 UTC
Issued: Thu 19 Oct 2006 07:05
Forecaster: GATZEN

SYNOPSIS

Long-wave trough spreads from western British Isles to Bay of Biscay. A tongue of warm/moist air mass is present E/NE of this trough over southern British Isles and central France and is displaced today by propagating cold front. To the south ... unstable air mass is present over western Mediterranean that spreads into central Mediterranean during the day. Mentioned cold front is also expected to travel into western Mediterranean ... where models indicate deepening frontal wave ... yielding easterly low level winds over northern and north-western Mediterranean.

DISCUSSION

Western/northern Mediterranean

A frontal boundary spreads eastward over western Mediterranean. In the range of this boundary ... latest soundings indicate rich boundary-layer moisture that is also expected to spread eastward. Given steep mid-level lapse rates ahead of the cold front ... substantial amount of CAPE is forecast by latest models ... and thunderstorms have formed during the night hours over western Mediterranean. Today ... weak upper short-wave trough is forecast to travel eastward over western Mediterranean ... and QG forcing supports a frontal wave centered near Corse. To the east and north ... low-level winds backing to southerly/easterly direction lead to increasing warm air/low-level moisture advection and increasing vertical wind shear. Thunderstorms are forecast to go on over western/central Mediterranean and should be quite well-organized as DLS is moderate. MCS ... probably bowing lines ... are quite likely ... capable of producing strong or even severe wind gusts. North and east of the frontal wave ... veering profiles support embedded mesocyclones ... and a slight chance for tornadoes/hail is expected ... spreading into Italy. High precip should lead to local flash flooding.

France, British Isles

Tongue of moist air mass is present from southern British Isles to central France. Along propagating cold front ... showers and thunderstorms are forecast especially over British Isles. Given quite strong LLS today ... isolated severe wind gusts or tornadoes may occur. Limiting factor is quite cool boundary-layer ... and chance seems to be too low for a level 1, though.

Aegean/southern Turkey

Weakening cut-off travels eastward over the region ... and showers/thunderstorms are forecast to develop in the range of this trough due to remaining moist low-level air mass ... weak CIN ... and some QG forcing. Given weak vertical wind shear, quite steep low-level lapse rates above the warm sea surface, and rich low-level moisture ... slight chance for waterspouts is forecast today.