Storm Forecast
Valid: Mon 13 Oct 2025 06:00 to Tue 14 Oct 2025 06:00 UTC
Issued: Sun 12 Oct 2025 13:54
Forecaster: TUSCHY

A level 2 was issued for heavy to excessive rain mainly for the coastal/offshore areas of the Gulf of Sant Jordi to the N Balearic Sea.

A level 2 was issued for the Gulf of Venice to the Balearic Islands mainly for large to isolated very large hail, severe gusts, a tornado risk (with a significant event not ruled out) and heavy rain.

A broad level 1 surrounds both (combined) level 2 areas with similar hazards but lowered probabilities.

A level 1 was issued for parts of the Atlas Mountains mainly for some hail and strong gusts.

A level 1 was issued for far SW Greece and offshore areas mainly for heavy rain and an isolated waterspout risk.

SYNOPSIS

An omega-block par excellence persists with rather hostile conditions for DMC activity over most parts of Europe. The main focus on an augmented severe risk evolves along the S fringe of the blocking anticyclone. A strong and de-amplifying wave crosses Spain E and enters the W Mediterranean during the overnight hours. Another upper trough affects the Ionian Sea, where clustering convection is forecast.

DISCUSSION

... Far E/NE Spain and the Balearic Islands ...

The difficult to forecast pattern regarding potential QPF maxima continues during this forecast period and even culminates in a bimodal severe weather risk.

The first area of interest will be the coastal/offshore areas of the Gulf of Sant Jordi to the N Balearic Sea, which reside along the apex of the eastward travelling upper wave. Ongoing mass response to lowering height fields to the SW cause an ongoing E/NE-erly BL flow event, where a moist marine airmass advects W. DLS resides at or below 5 m/s for most of the time, although a temporal increase until the afternoon is possible. During the daytime hours, with missing signals of more focused BL convergence, expect numerous N/NE ward drifting clusters from the S with locally heavy rain. From the afternoon into the overnight hours, the BL wind field breaks apart into a messy field of various convergence zones as the center of the upper wave shifts atop the area of interest. Scattered erratic moving clusters with heavy to isolated excessive rain are forecast.

Regarding QPF peaks, there is certainly a chance for a few excessive rain events. The past few days revealed 1h peak amounts in the 50-60 l/qm range. With offshore CAPE in the 500-1500 J/kg range and TPWs up to 40 mm, there is no reason why not to expect similar hourly peaks in slow moving clusters. Missing LL/3km shear precluded the more focused and quasi-staionary clusters during the past 2 days and this issue continues today. Hence we nudged the (probably rather aggressive) offhore level 2 near the coasts and expanded the level 1 more inland to account for isolated rain issues with slow moving convection.

The second area of interest will be atop the Gulf of Valencia and E towards the Balearic Islands. Overlapping rich BL moisture and a N-ward fanning EML create a belt of 1500 to 2500 J/kg MUCAPE with a sharp CIN gradient along the N fringe of the thermal ridge (with 850 hPa temperatures in the 15C + range). The passing mid-/upper-level impulse creates enough background support for CI although models still diverge regarding cap strength next to the Balearic Islands with a spread of 1-3 K in the 850 hPa layer. As most models show CI near/over the Gulf of Venice around noon onwards, we see no reason, why not to expcet eastbound shifting clusters, which move into rich CAPE/moisture.

EZ driven forecast soundings show locally nice loaded-gun-type signatures with MLCAPE up to 3000 J/kg and 3/6 km shear up to 20 m/s. This certainly favors supercells with all kind of hazards, including a strong tornado event (with LLCAPE in excess of 200-300 J/kg and curved hodographs), large to isolated very large hail, severe gusts and heavy rain. ICON is a bit less aggressive (MLCAPE up to 2500 J/kg and 15 m/s shear), but well organized multicells/supercells are certainly possible. It is not often that we see numerical convection evolving and moving into an EHI 6-8 and STP 2-3 setup so if everything comes together, we could also see a significant/long-tracked tornado event (offshore and/or onshore). Upscale growth into a RIJ driven MCS/bow is possible and even further upscale growth into an MCV event is not ruled out (with swaths of damaging gusts). Hence a broad area of outcomes with tracks well N/over or S of the Balearic Islands are possible. A broad level 2 was added right now and nowcast dictates the final/maximized severe risk.

As convection clears to the E, we could see a few lingering thunderstorms/showers with locally heavy rain near the Islands, but overall a noticeable lowering of the severe risk is forecast.

... Parts of the Atlas Mountains ...

A level 1 for a few high-based/elevated thunderstorms is forecast, which develop ahead of the approaching impulse. Strong downdraft gusts and some hail will be the main issue.

... SW Greece and offshore areas ...

A passing broad upper trough sparks numerous slow moving thunderstorms offshore and next to the coast. Weak to non-existent shear points to a heavy rainfall risk with clustering convection. An isolated waterspout is possible.