Storm Forecast
Valid: Sat 18 Oct 2025 12:00 to Sun 19 Oct 2025 06:00 UTC
Issued: Sat 18 Oct 2025 12:07
Forecaster: TUSCHY

A level 2 was issued for parts of Tunisia and offshore areas E of the Gulf of Gabes and S of the Malta Channel for severe gusts, large hail, excessive rain and a tornado risk.

A level 1 surrounds the level 2 for similar hazards with lowered probabilities.

A level 1 was issued for parts of the Galite Channel with a few waterspouts and heavy rain.

SYNOPSIS and DISCUSSION

This late written SWODY1 reflects a growing concern for an partially already ongoing and eastward spreading severe thunderstorm outbreak over parts of the S-CNTRL Mediterranean, which continues during the night.

A positive tilted trough with various vorticity maxima affects most of E into S-CNTRL Europe. A mobile low-amplitude wave races E along the S fringe of that upper trough and crosses the Ionian Sea E during the overnight hours.

During this time, weak BL mass response causes a gradually structuring and eastward shifting surface low, which passes by Malta just to the S and interacts with an unstable airmass with 1000-2000 J/kg offshore MUCAPE.
Kinematics within the depression's periphery are impressive to say at least: EZ point source soundings/hodographs just S of Malta with 30 m/s 0-3 km shear and up to 400 m^2/s^2 SRH3 show strongly looped hodographs with extreme near BL inflow into deviating storms. Long-tracked supercells with all kind of significant hazards are forecast, which temporarily back-building along existing convergence zones not ruled out. If this occurs near Malta or other offshore islands, we could see extreme onshore rainfall amounts. Otherwise damaging gusts, large hail and a tornado risk exits with this activity, which spreads E during the night. However it remains still uncertain how far N the warm sector expands and if Malta resides just to the N of the front with more elevated convection. Latest IFS-ENS takes the warm front near or over Malta during the night with most members.

A strong depression over the far NE North Atlantic advects a modified subtropical airmass N, which creates adequate MUCAPE during the night for scattered thunderstorms in the highlighted area during the passage of a partially occluded frontal system. Heavy rain (offshore) and strong gusts will be the main hazard.

A small level 1 was issued for ongoing and partially organized convection just N of NW Tunisia/NE Algeria. Slow moving thunderstorms bring heavy rain and a few waterspouts.

Elsewhere, numerous lightning areas were added but only with a lowered severe risk (e.g. a few waterspouts and isolated heavy rain).