Storm Forecast
Valid: Thu 10 Sep 2020 09:00 to Fri 11 Sep 2020 06:00 UTC
Issued: Thu 10 Sep 2020 09:42
Forecaster: GATZEN

A level 2 was issued across the west Tyrrhenian Sea and east Sardinia for heavy rain.

A level 1 was issued across the west Mediterranean and northern Algeria and Tunisia for heavy rain and large hail.

SYNOPSIS

A closed upper vortex is located across the west Mediterranean and slowly moves east. Ridging is present from Iberia towards the Alps and farther into the Black Sea just south of a strong polar jet that affects northern Europe. A weak trough is located across Turkey.

At lower levels, a plume of steep lapse rates has been advected ahead of the west Mediterranean trough towards Italy. Across the west Mediterranean, it overlaps with plentiful low-level moisture. Less moisture is present across the east Mediterranean where strong capping is present over many locations. Over Finland and north-west Russia, a strongly forced situation is ongoing, with a cold front moving into Russia and steep lapse rates following in the cold sector. Due some weak instability, storms have formed in a highly-sheared environment, but CAPE is very low and storms do not significantly contribute to the severe wind gusts threat.

DISCUSSION

West Mediterranean

Current storms are expected to go on and spread north and eastwards. With humid profiles, rather skinny CAPE, low LCLs and a deep warm part of the clouds, efficient rain production is forecast in these storms. Additionally, low-level inflow from the east can support some training to the east of Sardinia, where a level 2 was introduced for excessive rain. Additonally, some large hail is forecast in moderate to high (2000+ J/kg) MUCAPE and 10 to 15 m/s deep layer shear, especially in the southern parts of the risk area across northern Tunisia and Algeria.