Storm Forecast
Valid: Wed 15 Nov 2017 06:00 to Thu 16 Nov 2017 06:00 UTC
Issued: Wed 15 Nov 2017 07:02
Forecaster: PUCIK

A level 2 was issued for Southern and Western Greece mainly for excessive precipitation, large hail and tornadoes.

A level 1 was issued for Greece mainly for excessive precipitation and to the lesser degree for tornadoes.

A level 1 was issued for N Tunisia and parts of Central Italy mainly for excessive precipitation.

SYNOPSIS and DISCUSSION

A strong zonal flow is observed over much of northern Europe with a series of short-wave troughs that progress over the region. Lacking lower tropospheric moisture will preclude more widespread thunderstorm risk, but isolated thunderstorms will be possible e.g. over the Baltic states as a short-wave crosses the region during the evening hours.

More prominent risk will be confined to the Mediterranean, where a cut off low resides, centered over Sicily. Particularly at its forward flank, in southerly flow, more abundant lower tropospheric moisture will be advected towards Greece, the Ionian and Aegean Sea. At the same time, a short-wave trough will eject from south, including a jet-streak. Increasing synoptic scale forcing for ascent, advection of EML from south and increase in the vertical wind shear will enhance the severe thunderstorm risk over the region, particularly over the southwestern coastline of Greece towards the overnight hours. Excessive rainfall will be the primary risk, but large hail may occur as well with supercell thanks to the advection of steep lapse rates over the area. At the same time, tornadoes will be possible too given LLS around 10 m/s. A lvl 2 is introduced for an area with the biggest overlap of all 3 mentioned severe weather threats.

Lvl 1 for excessive precipiation was also introduced for parts of N Africa and Italy, where a strong lower tropospheric flow will impinge on the coastline, resulting in a forced ascent over the coastline / mountains and repetitive development of cells over the area.