Storm Forecast
Valid: Tue 26 Mar 2019 06:00 to Wed 27 Mar 2019 06:00 UTC
Issued: Mon 25 Mar 2019 23:08
Forecaster: DAFIS

A level 1 was issued for Poland for severe convective wind gusts.

A level 1 was issued for Italy and parts of Corsica mainly for large hail or large amounts of small hail, and waterspouts.

A level 1 was issued for parts of Greece, Bulgaria and Albania for large hail or large amounts of small hail, and severe wind gusts.

SYNOPSIS

A positively tilted long-wave trough is extending from NE Europe towards Italy and is under the influence of the strong ridge more to the west, and their interaction is about to result in a wave-breaking and the formation of a cut-off low in West Mediterranean. A secondary wave is found in the southeastern part of the trough and brings a PVA over the S Balkans. At the surface, the high-pressure system in West Europe is intensifying and the blocking pattern seems that will last for at least the following 5 days. On the eastern periphery of the anticyclone, several low-level vortices are driven by upper-level forcing (embedded short-wave troughs) and some thunderstorms are expected, mostly in the Balkans, but the limited amount of moisture and generally weak thermodynamics limit the potential for widespread severe weather events.

DISCUSSION

.... Poland ....

Strong baroclinicity is expected over Poland as cold arctic air masses have found a way to travel south to Central Europe. The strong northerly flow over the Baltic Sea will enhance the moisture content of the air mass and some CAPE is forecast from various models. Several short convective cells are expected, few of them weakly electrified, but able to produce severe wind gusts. The 15-20 m/s 850hPa wind speeds can easily be translated to the ground within these convective cells. Locally large amounts of graupel or small hail cannot be ruled out.

.... Italy and Corsica ....

A cut-off low destabilizes the area, especially the air masses over the Tyrrhenian Sea. Large-scale lift is expected under a strong vorticity lobe that enters the Mediterranean. A cyclone near the surface is developing as a response to the upper-level disturbance, but low-level fluxes of moisture and heat don't seem impressive, with models showing only meager MLCAPE, so thunderstorms are not expected to organize in long-living MCSs. Locally thunderstorms may produce large amounts of small hail or graupel due to low wet-bulb temperatures and steep low/mid level lapse rates. Moreover, some waterspouts may form, especially near the coasts of W Italy where 0-1km shear is minimized and winds are the weakest.

.... Greece, Bulgaria, Albania ....

A short-wave impulse is making its way from S Italy towards the Balkans, bringing low geopotentials with steep lapse rates. We expect diurnally driven thunderstorms into this unstable environment. Weak storm motion with skinny CAPE profiles support the forecast of large amounts of small hail. Forecast soundings also show areas with dry mid-level air masses, where enhanced downdrafts through evaporation, may result in severe convective wind gusts at the surface.