Storm Forecast
Valid: Thu 09 Sep 2010 06:00 to Fri 10 Sep 2010 06:00 UTC
Issued: Wed 08 Sep 2010 15:09
Forecaster: GATZEN

A level 1 was issued for southern Italy and southern Adriatic mainly for excessive rain.

SYNOPSIS

A broad high is present over northern Europe. To the west, a sharp mid-level trough spreads into Central Europe and cuts off over the Alpine region. This is associated with a strong mid-level jet curving around the troughs base into the west Mediterranean and further into the southern Adriatic Sea. A tongue of warm air spreads into the Balkans ahead of this trough, whereas cold low level air over northern and Central Europe advects into the west Mediterranean Sea.

DISCUSSION

Sicily to southern Adriatic

Cold air spreads into the west Mediterranean region. The cold front will slowly propagate eastwards during the period. A tongue of moist and warm low-level air is situated in the range of the frontal boundary and advects into the Balkans. Steep mid-level lapse rates present ahead of the mid-level trough will overlap the rich low-level moisture, and latest models predict CAPE around 2000 J/kg. Quite robust convective inhibition can be expected given very warm air atop of the boundary-layer. Increasing lift along the frontal boundary is expected during the day when the mid-level trough approaches and DCVA sets in. Showers and thunderstorms are forecast especially during the second half of the period and will spread north-eastwards. These thunderstorms are forecast to organize in the range of the south-westerly flow reaching 15 m/s at the 700 hPa level and 20 m/s at the 500 hPa level, leading to around 15 m/s deep layer bulk shear. Isolated severe weather including tornadoes is expected. A widespread severe weather event is not forecast as the thermodynamic profiles are relatively weak. The main threat will be excessive rain along the eastern Adriatic coasts.

Central Mediterranean

Underneath the trough axis, some showers and thunderstorms will likely develop during the day. Weak vertical wind shear and low-level forcing will not assist organized convection. Waterspouts are not ruled out in the weakly-sheared environment.