Storm Forecast
Valid: Thu 17 Mar 2016 06:00 to Fri 18 Mar 2016 06:00 UTC
Issued: Wed 16 Mar 2016 19:44
Forecaster: GATZEN

A level 1 was issued for the Ionian Sea mainly for excessive rain and to a lesser extent large hail.

SYNOPSIS / DISCUSSION

Quasi-stationary blocking over the British Isles and an intense arctic trough over north-east Europe yield a strong jet from western Scandinavia to the Ukraine and south-west Russia. Cold and dry air masses limit storm potential over the north-east, whereas mid-level ridging is not supportive across the British Isles and the North Sea / southern Baltic Sea region, where rather moist air masses are located.

Southern Europe is dominated by low geopotential and cold mid-level temperatures. An intense vort-max over south-western France leads to strong dynamics over the Mediterranean thanks to a 30 m/s mid-level jet at its southern periphery. The French trough weakens gradually, and vort-maxima travel east across the south Mediterranean providing QG forcing.

Affected air masses are rather moist and continue to spread north-westward into the Ionian Sea region. Overlapping with steep lapse rates and frontogenetical forcing, thunderstorm activity is forecast to go on through-out the period. Vertical wind shear is weak over the northern portions of the region, where main severe threat is excessive, albeit partly non-convective precipitation from training, slow-moving clusters. Further south-east, 0-3 km vertical wind shear increases strongly near an elevated mixed layer that advects north-east ahead of the trough center. Storm organization will be better, including well-developed multicells. Surface-based storms become unlikely in this warm air as it spreads over the cool sea surface, but large hail may be possible.

Showers and thunderstorms are also forecast over most portions of the central and also west Mediterranean. Weak vertical wind shear limits storm organization. Waterspouts are possible with these storms.