Storm Forecast
Valid: Thu 23 Jul 2026 06:00 to Fri 24 Jul 2026 06:00 UTC
Issued: Wed 22 Jul 2026 20:16
Forecaster: TUSCHY

A level 2 was issued for parts of SE Italy towards the Ionian Sea and adjacent areas mainly for large to very large hail, damaging gusts and heavy rain. An isolated (strong) coastal tornado is possible.

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

A level 1 was issued for Slovenia into Croatia mainly for some hail, gusts and heavy rain.

A level 1 was issued for parts of NE Italy and the N Adriatic Sea mainly for large hail, severe gusts and an isolated coastal tornado event.

A level 1 was issued for parts of E Spain mainly for isolated large hail and severe gusts.

A level 1 was issued for SW Russia mainly for large hail and severe gusts.

SYNOPSIS

The static pattern over Europe persists. The subtropical anticyclone and a strong NE Atlantic ridge connect over W Europe and face a deep trough over E Europe. A progressive short wave trough circles the main longwave trough while crossing CNTRL Europe towards the CNTRL Mediterranean.

Numerous cold fronts push E towards Russia as otherwise not much input from synoptic-scale fronts is anticipated. Much of the forecast DMC activity arises from the mesoscale (like convergene zones and the orography).

DISCUSSION

... E Spain ...

What an impressive setup with a barotropic ridge still centered over SE Spain, revealing negative PV values along the 320 K isentrope. 12Z sounding from Murcia (22nd July) embodies this environment perfectly!

The ongoing marine heatwave supports a very moist marine layer with dewpoints in the mid to upper twenties, which advects onshore with regional upslope transport into the mountains. Again, we talk about an impressive 25K and more zonal dewpoint gradient along the coast towards CNTRL Spain, where LCLs push in excess of 4km AGL.

Similar to the previous days it remains very challenging to pinpoint the area of CI, as not much (if any) synoptic-scale lift is forecast. A weak wave circling the tip of the ridge could induce spotty CI, also reflected in ENS data with somewhat augmented QPF probabilities in the maximum range. This area was highlighted with a lightning area and level 1 to indicate a local hail and gust risk. The lightning area was expanded S to catch some elevated activity in response to weak isentropic lift along the western edge of the ridge. Similar to the past few days it remains unclear, if any cell can root into the extremely unstable airmass along the E coast (elevated MUCAPE up to 7000 J/kg !). Confidence is low as are the signals in the deterministic and ENS runs, so we keep the level area pinned to the orography.

Nowcasting is once again needed to catch an augmented severe risk in case we see an updraft rooting into the CAPE-rich environment along the coasts.

... S Italy into the Ionian Sea ...

A 2 sigma anomaly H25 jet affects the area of interest. Initially undisturbed, synoptic-scale lift improves during the evening and overnight hours with an approaching trough from the N.

An ongoing 4-5K (positive SST anomaly) marine heat wave assists in BL dewpoints in the mid twenties or mixed BL mixing ratios in the 16-18 g/kg range. As the trough approaches from the N, BL winds veer and push this very moist air further E towards the Ionian Sea

The mentioned trough sparks numerous elevated convection during the evening onwards over CNTRL Italy towards the Adriatic Sea, which turns near surface based offshore, where 2000 J/kg MUCAPE and 15 m/s support organized multicells and a few supercells.

Beyond midnight, an upscale growing cluster with embedded bow echoes and supercells races S, affecting Puglia in Italy and thereafter the E Ionian Sea/coasts of SW Albania and W Greece as this convection interacts with the high energetic airmass. MUCAPE in the 2000-3000 J/kg range and DLS in excess of 25 m/s (15 m/s 3 km shear) support organized DMC with swaths of damaging gusts and large to very large hail. Heavy rain is another concern next to a coastal tornado event.

We expanded the level 1 and 2 far W towards the SE Tyrrhenian Sea. CI is less certain but reflected in EPS/ENS data (median and maximim of QPF). Any initiating cell would be explosive in 3000 J/kg MUCAPE and 25 m/s DLS in a virtually uncapped environment. A few damaging supercells with very large to giant hail and damaging gusts area forecast next to heavy rain. In addition, if we see a supercell traversing the coastal areas SE, a strong tornado event would be possible.


... NE Italy and N Adriatic Sea, Slovenia and parts of Croatia ...

A southward swinging upper trough axis adds abundant lift on the synoptic scale to initiate scattered thunderstorms over Slovenia during the afternoon onwards. This convection evolves in weakly capped 400-1000 J/kg MLCAPE and 15-20 m/s DLS. A few organized multicells and transient supercells bring isolated large hail, strong to severe gusts and heavy rain on a local scale. The attendant outflow spreads S but also SW towards the N-Adriatic Sea.

The combination of the SW ward surging outflow, mid-level cooling and ongoing northward advected marine air towards a weak low over N Italy create a confined area with 2000 J/kg MUCAPE and 20 m/s DLS atop the Gulf of Venice. This could support numerous left moving right movers (admit an unsual hodograph geometry for this time of year) and a few supercells could bring large hail, severe gusts and heavy rain to the N Adriatic Sea and adjacent areas like S Veneto and E Emilia Romagna. An isolated tornado event along the coastal areas is not ruled out, where weak CIN faces impressive SRH in an adequate LCL environment.

... SW Russia ...

A belt of favorble CAPE/shear exists and organized high-based convection brings a large hail/severe gust risk and a level 1 was added.