CONVECTIVE FORECAST
VALID Thu 21 Jul 10:00 - Fri 22 Jul 06:00 2005 (UTC)
ISSUED: 21 Jul 10:36 (UTC)
FORECASTER: GATZEN

There is a slight risk of severe thunderstorms forecast across northeastern Italy

SYNOPSIS

Unseasonably intense trough is present over southern Baltic Sea ... and cool maritime airmass dominates most of northwestern, northern and central Europe. Rather low geopotential is also present over eastern Europe, where warm and unstable airmass has spread northward into northwestern Russia. At the base of the European trough ... relatively stable airmass is present in the Mediterranean underneath a broad subtropical jet evident at the 200 hPa level.

DISCUSSION

...Northern Itlay...
A relatively weak jet streak (20 m/s @ 500 hPa) propagates southeastward over France ... leading to DCVA over northern and central Italy. In the wake of the Alps ... remaining warm boundary layer and quite steep mid-level lapse rates are present. Underneath the inversion ... moisture has recovered during the last couple of hours ... and CAPE is expected to reach around 1000 J/kg in the afternoon. Amount of moisture is unclear ATTM ... and low-level moisture should increase to the east, while it should be knee-deep in the western parts ... where CIN may be large and inhibits initiation. However ... isolated to scattered thunderstorms may form. Thunderstorms that form may be severe given easterly surface wind at the northern flank of low pressure system over central Italy ... yielding to vertical wind shear. Supercells and multicells are expected ... capable of producing isolated large hail, severe wind gusts and probably tornadoes. Thunderstorms should move eastwards, where low-level moisture will increase. However ... decreasing vertical wind shear will be more favorable for non-severe storms there ... and thunderstorms may merge into clusters ... with intense precip and strong wind gusts the most significant threat. However ... one or two reports are not ruled out over northeastern Italy, though.

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