Storm Forecast
Valid: Thu 18 Oct 2007 06:00 to Fri 19 Oct 2007 06:00 UTC
Issued: Thu 18 Oct 2007 05:25
Forecaster: GATZEN

SYNOPSIS

A high amplifies over W Europe, while an outbreak of polar air mass is directed towards central Europe. Along the periphery of associated sharp trough, a strong northerly jet streak will cross the Alps today, leading to strong QG forcing over the northern Adriatic. Warm and unstable air mass over south-western Mediterranean will be replaced by cooler air mass during the period.

DISCUSSION

Northern Adriatic

A tongue of warm and moist low-level air mass is present from the Tyrrhenian Sea to northern Adriatic region in the range of a weak low pressure area. It will remain until katabatic winds will lead to cold air advection in the afternoon/evening hours, while mid-level air mass is expected to cool substantially in the range of the propagating trough. Although latest ascends show a strong inversion, it is expected that some instability will develop in the afternoon/evening hours, and given QG forcing, thunderstorms are expected to form. Convection may be organized as strong vertical wind shear is forecast. While low-level veering is not strong, at least multicells are expected, capable of producing isolated large hail and strong to severe wind gusts. Thunderstorms will likely merge into clusters in the evening/night hours over the Adriatic Sea, spreading southwards, where vertical wind shear is expected to weaken and severe thunderstorms are not expected at this time.

Southwestern Mediterranean

Steep low-level lapse rates and strong low-level buoyancy are indicated by latest ascends. Thunderstorms are forecast to go on during the day, posing a threat of tornadoes and/or waterspouts, dependent on small-scale favorable vertical shear profiles although synoptic scale shear that does not look favorable. Later in the day, a cold front will enter the region, and thunderstorms will likely cluster along this front moving southward, while chance for tornadoes is forecast to decrease.