Storm Forecast
Valid: Tue 12 Nov 2019 06:00 to Wed 13 Nov 2019 06:00 UTC
Issued: Mon 11 Nov 2019 22:08
Forecaster: DAFIS

A level 2 was issued for S Italy, S Croatia, Bosnia and Herzegovina, Montenegro, W Albania and parts of Greece for excessive precipitation, severe wind gusts, large hail, and tornadoes.

A level 2 was issued for S Italy, Croatia, Bosnia and Herzegovina, Montenegro, W Albania and Greece for excessive precipitation, severe wind gusts, and tornadoes.

SYNOPSIS

A deep trough with an axis over the western Mediterranean associated with a thinning PV streamer over Italy is destabilizing the largest part of the Mediterranean basin. On Tue 12/11 a cut-off low will form over Tunisia and Libya, while the PV streamer will attain a shape like "hook" of "treble clef", an indication of the formation of warm seclusion in the low-mid troposphere. Some NWP models show explosive cyclogenesis in southern Italy with up to 17 hPa drop in 24 hours. Nevertheless, a vigorous cold front is about to cross southern Italy and western Balkans resulting in severe weather events discussed below.
In northern Europe, several short-wave troughs bring unseasonably cold air masses and only weak instability is expected close to the coasts of France, Belgium, the Netherlands, and Spain.

DISCUSSION

.... S Italy, S Croatia, Bosnia and Herzegovina, Montenegro, W Albania, and Greece ....

An elevated mixed-layer in the warm sector of a cyclone currently placed in the Gulf of Sirte, creates large values of CAPE in the Ionian Sea and Greece. The cold front will propagate fast east towards Greece and the Balkans providing strong lift to unstable air masses. Several storm clusters will probably form on this boundary and will pose a threat first to southern Italy on the morning of Tuesday and then in the afternoon to the western coasts of the Balkans. Locally more than 100 mm of accumulated precipitation is expected in less than 6 hours. Given the high values of SREH and MLCAPE, some storms may become supercells able to produce all kinds of severe weather. Tornadoes are well possible in South Italy in the morning and later in Greece. At the coasts of the Tyrrhenian Sea the main threat will be the severe wind gusts.

During the evening and late-night of Tuesday, the severe weather threat will be mostly found in the Aegean Sea and in Crete where more than 1500 J/kg MLCAPE will overlap with 15-20 m/s DLS and more than 100 m2/s2 SREH0-3km. Supercells may produce large hail, severe wind gusts, excessive rainfall, and tornadoes. Especially the persistent southerly flow may lead to flash floods in many areas.
Some waterspouts are also expected in the Ionian Sea in the early morning of Wednesday 13/11.