Storm Forecast
Valid: Thu 24 Jul 2025 06:00 to Fri 25 Jul 2025 06:00 UTC
Issued: Wed 23 Jul 2025 22:05
Forecaster: PUCIK
A level 2 was issued across SE Spain and the Balearic Sea mainly for large to very large hail, severe wind gusts and heavy rainfall.
A level 1 was issued for NE France, SW Germany and central to N Switzerland mainly for heavy rainfall.
A level 2 was issued for NW Italy and NE Italy, N Slovenia, Austria mainly for large to very large hail, severe wind gusts and heavy rainfall.
A level 1 was issued for N Austria and W Hungary mainly for large hail, severe wind gusts and heavy rainfall.
A level 1 was issued for E Czechia and W Slovakia mainly for severe wind gusts and heavy rainfall.
A level 1 was issued for Corsica mainly for large hail.
A level 1 was issued for central Finland mainly for severe wind gusts and large hail.
A level 1 was issued for Romania and Bulgaria mainly for large hail and severe wind gusts.
A level 1 was issued for SW Norway, S Sweden, Denmark, NE Poland, Lithuania, E Latvia, S Estonia, NE Belarus and W Russia mainly for heavy rainfall.
DISCUSSION
... SE Spain to the Balearic Sea ...
Pronounced synoptic-scale lift will overspread the area from the early morning hours, related to the deep trough approaching from nrothwest and warm air advection overspreading the cool air at the surface. Both orography and the cold front and its anabatic circulation will act as mesoscale lifting mechanisms. Near the surface, easterly flow is simulated with cool and moist airmass spreading far inland. With strengthening westerly flow aloft, long and straight hodographs are simulated. Given cool boundary layer, much of the convection will be elevated, with MUCAPE values ranging from 1000 to 2500 J/kg. Majority of CAPE will be in the cold part of the troposphere. A mix of supercells and mesoscale convective systems is forecast. Supercells will result in large to very large hail and severe wind gusts. The latter threat will be more pronounced over the southern half of the area. Numerous rounds of storms are anticipated, with a chance of very heavy rainfall event in case convective system aligns with the flow in the absence of stronger cold pools. Storms will exist over the sea already in the morning hours. An increase in the activity over land is expected later in the afternoon and storms will persist into the night as they spread south and east.
... Corsica ...
A small probability exists that a supercell with large to very large hail and severe wind gusts will develop over the island given intense vertical wind shear and solid CAPE over the coastlines. While this scenario is unlikely, the overall probability of severe weather surpasses the Lvl 1 criterion.
... NW to central-N Italy ...
The first round of storms is anticipated in the morning hours with lingering threat of heavy rainfall and large hail. The next round of activity is anticipated after 15 UTC with initiation over the mountains and storms spreading over the plains, starting near Torino and moving towards Milan, as suggested by several high-resolution models. With MLCAPE between 1000 and 1500 J/kg and 0-6 km bulk shear around 25 m/s, severe storms are likely, including supercells capable of large to very large hail and severe wind gusts. Towards the mountains, storm interaction may lead to larger clusters of storms capable of heavy rainfall. Further southeast, CAPE-shear parameter space will be still supportive of severe storms, but initiation is less certain. Some models suggest a new round of storms in the early morning hours of Friday, which would again bear the severe weather risk. The uncertainty leads to a gap between the Lvl 2 areas.
... NE Italy through Slovenia, Austria, W Hungary into Slovakia ...
Morning storms from NW Italy will continue moving eastwards, resulting in redevelopment over NE Italy. Strong vertical wind shear exceeding 20 m/s in the 0-6 km layer suggests a mix of supercells and linear segments. Storms will spread east and northeast in the afternoon hours with further initiation over the mountains. CAPE and shear parameter space will be most conducive to severe storms in a belt from NE Italy to extreme W Hungary. Here, large to very large hail and severe wind gusts, combined with heavy rainfall threat, are forecast. Very large hail will be mitigated to some degree by rather skinny CAPE profiles. Severe wind gusts will be limited by rather low LCLs and will be conditional on the formation of a linear segment. Further north, WAA regime along the frontal wave will lead to another round of storms starting north of the Alps and spreading towards E Czechia and W Slovakia. The first storms that form may be supercells. ICON-EU shows impressively curved hodographs in the evening hours over SW Slovakia, but this is not reproduced in other models and also the SRH will not be effective for storms due to their elevated nature late into the evening. Thus, it seems that a Lvl 1 is sufficient for an initial large hail threat transitioning to wind/rain threat as storms cluster and move north.
... Switzerland through SW Germany into France ...
Across S Switzerland, well-organised storms are still expected given stronger vertical wind shear. Given moist profiles, main risk will be heavy rainfall, with an exception of southernmost tips, such as Ticino, where large hail will be possible. Further north and northwest, towards Germany and France, weaker shear, moist profiles and weaker mean wind will yield the dominance of heavy rainfall.
... Romania ...
Isolated to scattered storms will initiate over the mountains in an environment of MLCAPE around 1000 J/kg and bulk shear around 15 m/s. Isolated large hail and severe wind gusts are forecast with stronger storms, some of which may become transient supercells. The highest threat will be between 12 and 15 UTC.
... Bulgaria ...
A marginal Lvl 1 is necessary for the mountainous parts, where there is a chance of isolated storms developing in the afternoon hours. While the probability of initiation is rather low, developing storms can become severe and produce large hail or severe wind gusts due to the 0-6 km bulk shear around 15 m/s, deep boundary layer and majority of CAPE below -10 deg C.
... Finland ...
WAA regime will yield curved hodographs with 0-6 km bulk shear of around 15 m/s and SRH over 200 m2/s2 in the 0-3 km layer. Supercells are expected to develop with threats of large hail and severe wind gusts. Questionable degree of initiation and also the magnitude of CAPE precluded the issuance of Lvl 2.
... SW Norway, Denmark, S Sweden ...
Moist profiles featuring low LCLs, substantial CAPE in the warm part of the cloud and weak mean tropospheric wind will result in enhanced threat of heavy rainfall.
... NE Poland into the Baltics into Russia ...
Scattered to widespread storms will initiate in a tongue of moist airmass and in the core of a cut-off low. Forecast profiles show low LCLs, abundance of CAPE in the warm part of the cloud, high RH till the upper troposphere and weak mean wind. The combination of these factors will result in another day of storms bringing heavy rainfall.
