Storm Forecast
Valid: Thu 11 Aug 2022 06:00 to Fri 12 Aug 2022 06:00 UTC
Issued: Wed 10 Aug 2022 15:38
Forecaster: TUSCHY

A level 2 was issued across Sicily into S Italy mainly for heavy rain.

A level 1 surrounds that level 2 for heavy rainfall and isolated hail events. A few waterspouts are possible.

A level 1 was issued for parts of the CNTRL Ukraine mainly for large hail and heavy rain.

A level 1 was issued for the mountainous regions of Greece into Bulgaria mainly for heavy rain.

SYNOPSIS

Static pattern with positive height anomalies over Scandinavia persists during this time frame. A pronounced cold-core vortex over the W-Ukraine moves W towards Austria, whereas its radius of influence also covers most of the CNTRL Mediterranean with lowered thickness values. Another cyclonic vortex is hanging around to the W of Portugal and this one advects a hot and dry African air mass towards France.

Despite a dissolving synoptic-scale front over far E Europe/W Russia, no recognizable boundary plays a role in today's thunderstorm forecast.


DISCUSSION

... S-Italy and surrounding areas ...

Certainly the main show is once again forecast over this region. The main story is both the diurnal see breeze activity but also a passing mid-level wave.

First, isolated offshore activity from the previous night persists for some time, before onhsore convection dominates the picture once again (CI from 9-10Z onwards). Onshore moving sea breezes warm up and push BL moisture in the upper tens/lower twenties with coastal MUCAPE in the 1000-2000 J/kg range. DSL in the 4-8 m/s range is once again present with clustering mountain convection pushing strong outflow boundaries offshore towards the Tyrrhenian/Adriatic Sea with some offshore CI during the evening onwards. Heavy rain with flash flooding is the main hazard next to isolated hail. In addition a spotty spout risk exists along offshore convergence zones. Convection diminishes beyond sunset.

The same for Corse and Sardegna.

A potential impactful overnight thunderstorm scenario may evolve over the Tyrrhenian Sea towards Sicily and surrounding areas. A passing vort max with enhanced Q-vector convergence may induce an uptick of offshore thunderstorm activity along residual outflow boundaries and clustering/slow moving convection may overspread the S Tyrrhenian Sea and approach Sicily beyond midnight from the N. Excessive rain may become an issue as forecast profiles indicate impressive moisture within most of the troposphere and BL mixing ratios atop the anomalous high SSTs with 14 g/kg readings. Although most models keep highest QPF amounts offshore until 06Z we see no reason why this activity should not affect the coastal areas (e.g. as cold pool driven forward motion increases). A confined level 2 was added where we expect an augmented risk for flash flood producing thunderstorm events and we expanded it NE for the daytime activity.

... CNTRL Ukraine ...

A level 1 was added as 12 g/kg LL mixing ratios to the S of the dissolving boundary pool beneath neutral mid-level lapse rates. Combined with diurnal heating, this setup offers 1-2 kJ/kg MLCAPE in a 10 m/s DLS environment. Initiating storms pose a large hail and heavy rain threat before clustering convection turns the risk more to heavy rain with strong to isolated severe wind gusts. A weakening trend is forecast around sunset.

... Rest of Europe ...

Numerous regions with augmented thunderstorm chances exist with local flash flood issues due to slow storm motion (e.g. Greece to Bulgaria, where a level 1 was added) but most of the thunderstorm activity should stay sub-severe for most of the time.