Storm Forecast
Valid: Fri 13 Apr 2012 06:00 to Sat 14 Apr 2012 06:00 UTC
Issued: Thu 12 Apr 2012 22:12
Forecaster: TUSCHY

A level 1 was issued for the E-Ionian/SE-Adriatic Sea mainly for heavy rainfall and an isolated large hail / waterspout event.

A level 1 was issued for the SW-coast of Italy mainly for heavy rainfall and an isolated large hail / waterspout event.

SYNOPSIS and DISCUSSION

A deep meridional upper trough covers most of Europe. Numerous disturbances round this feature and result in various places with enhanced convection.

At the surface a deepening low enters the Tyrrhenian Sea from the SW. Only slow movement to the E/NE is forecast.

During the forecast, CAPE and shear fields remain displaced over most of the time. Hence, the main hazard will be marginal hail and gusty winds onshore, heavy rainfall and an isolated waterspout event offshore and along the highlighted coasts.

A more robust thunderstorm event is forecast over the Ionian Sea, S-Italy and S-Adriatic Sea after midnight, as the LL depression advects a warm/moist airmass to the NE and the left exit of a 30 m/s mid level streak moves in from the SW. A level 1 was issued mainly for heavy rainfall and isolated large hail, next to an isolated waterspout.

Another level 1 was issued for SW Italy next to the center of the well structured LL depression. Training storms may affect the highlighted area, where models show enhanced probabilities for locally up to 70 mm/12 h (after 18 Z).

The Balearic Islands may see an upgrade due to an isolated large hail risk during the evening hours onwards, but lack of LL moisture keeps forecast CAPE low. However, mid-level lapse rates are steep with 20 m/s NW-erly flow, so any stronger storm may pose a large hail risk. Confidence in a more concentrated hail swath is still too low for a level 1.