Storm Forecast
Valid: Mon 19 Nov 2012 06:00 to Tue 20 Nov 2012 06:00 UTC
Issued: Sun 18 Nov 2012 21:56
Forecaster: TUSCHY

A level 1 was issued for parts of the Ionian Sea mainly due to an heavy to isolated excessive rainfall risk and an isolated tornado event.

SYNOPSIS

A broad upper trough over the C-Mediterranean shifts to the east and becomes more or less stationary atop the Ionian Sea. Unsettled conditions continue over most parts of the Mediterranean.
The frontal zone is far displaced to the north with numerous strong low pressure areas affecting Ireland and Scotland during the forecast period. Any thunderstorm activity west of Ireland/Scotland remains very sporadic.

DISCUSSION

... Ionian Sea and surrounding areas ...

The quasi-stationary upper low advects a moist and weakly capped air mass from the far S-Mediterranean towards the Ionian Sea, where a pronounced NW-SE aligned convergence zone becomes the main trigger for persistent CI mainly from far S-Italy to Crete. High-level divergence beneath the left exit of a 50 m/s upper jet and the approaching trough insert adequate forcing, so scattered to widespread DMC development is anticipated. Despite supportive CAPE for longer lived and deep convection, 6 km bulk shear remains below 10 m/s for most parts despite the far E-Ionian Sea where 15 m/s DLS occur. With persistent development of showers and thunderstorms, heavy to isolated excessive rainfall amounts will be the main hazard. In fact, far S-Italy may see a training cluster of DMC due to a persistent 15 m/s LLJ along a pronounced LL convergence zone and increasing LL instability from noon onwards before another cluster may affect the southern parts of the level 1 area during the overnight hours, where isolated 100 mm/24 h are possible over S-Greece.

An isolated tornado event can occur either along the W coasts of Greece (marginal enhanced LL directional shear) and along the southern coasts of Italy (better LL CAPE and enhanced vorticity). Latest data prints somewhat higher tornado probabilities over S-Italy with evolving convergent flow pattern.

Isolated to scattered thunderstorms are forecast within the area of influence of this low (W-C Mediterranean), but nothing severe is anticipated.

During the end of the forecast, an heavy upslope rainfall event may start over the far NW Aegean Sea (e.g. SW of Thessaloniki), but expected rainfall amounts remain below a level 1 (beside missing electrified convection until 06Z).