Storm Forecast
Valid: Fri 13 Jun 2025 06:00 to Sat 14 Jun 2025 06:00 UTC
Issued: Thu 12 Jun 2025 22:16
Forecaster: PUCIK
A level 2 was issued across parts of Spain, France and Belgium mainly for large to very large hail, damaging wind gusts and to the lesser extent for heavy rainfall.
A level 1 was issued across these countries for the same threats but with lower probability.
A level 1 was issued across England mainly for heavy rainfall and large hail.
A level 1 was issued across NW Italy and S Switzerland mainly for heavy rainfall and large hail.
A level 1 was issued across Greece mainly for heavy rainfall and large hail.
A level 1 was issued across central Russia mainly for severe wind gusts and large hail.
A level 1 was issued across parts of the Caucasus region mainly for large hail.
DISCUSSION
... E Spain ...
A system of local convergence zones is simulated between the valleys/sea and the higher terrain with the most pronounced one in between of the Ebro river valley and the Sistema Iberico. Here, a pronounced dry line will establish. Majority of models simulate convective initiation in MLCAPE around 2000 J/kg and 0-6 km bulk shear around 20 m/s. Coverage of storms should be rather isolated, but any sustained storm will likely become a supercell capable of large to very large hail and severe wind gusts. Convective initiation is less certain further south, but the conditional risk of severe weather given initiation success remains high, warranting an elongated Lvl 1.
... Pyrenees towards Massif Central ...
Scattered storms will form on the mountains in the afternoon hours. Conditions will be conducive to severe weather with MLCAPE around 1000 J/kg and 0-6 km shear around 20 m/s. Large hail will be likely and very large hail is possible with supercells. Towards the evening and early night hours, storms may spread towards the lowlands of southern France, where MLCAPE values of 3000 to 4000 J/kg are forecast in the afternoon hours. However, at that time storm initiation will be prevented by the layer of CIN and dry air near the LFC. Profiles will become moister and CIN will be reduced for the MU parcel in the evening hours as a cold front approaches from west. CAPE will still remain high and 0-6 km shear of around 15 m/s is forecast. Storms will likely be severe, but their coverage is highly uncertain and models are not in agreement. While AROME shows a powerful convective system, some of the high-resolution models show barely any storm in the region. Will keep a Lvl 2 for large to very large hail and damaging wind gusts for the region, but the mentioned uncertainties need to be revisited as newer data come in.
... W/NW France towards BENELUX ...
Uncertain situation is forecast also here, especially concerning the corridor of the most intense storms and their timing. A diffuse cold-front will linger over W France in the morning hours with some elevated showers or thunderstorms possible early on. Towards the afternoon, a wave is forecast to develop on the front ahead of the short-wave through at 300 hPa approaching from the south. As the surface flow turns towards east across north France, hot airmass with deep boundary layer will mix out the moisture and create a dryline with moist airmass to the west of it overlapping with steep mid-tropospheric lapse rates. Exact placement of the dryline is a main source of uncertainty. For example, ECMWF places it further west than the ICON-EU. Its location will be crucial in the placement of the corridor of the most intense storms.
Within the moist airmass, MLCAPE values of 1500 to 3000 J/kg are forecast, overlapping with 15 to 20 m/s of 0-6 km bulk shear. Thus, parameter space will be favorable for well-organised, severe storms capable of large to very large hail and damaging wind gusts. Storms will most likely start forming between 12 and 15 UTC over W France along the developing warm wave and will spread N and NE towards Belgium and England. A mix of supercells and linear segments is likely. Storms along the western fringe of the Lvl 2 and towards the western edge of the Lvl 1 will be elevated, but with still enough MUCAPE and effective shear for severe weather threat, most likely in form of large hail or heavy rainfall. As the low-level lift moves with the warm wave towards England, it is not very likely that storms spread far into the hot and drier airmass. This option can't be ruled out though and this led to a generous eastern and northern margin of the Lvl 1.
... England ...
A wave of elevated storms will affect the area during the overnight hours as the frontal system passes along with the short-wave trough. Over SE England, forecast profiles show substantial MUCAPE with moderately strong effective shear that can sustain large hail production in stronger cells. Otherwise, heavy rainfall will be the main threat.
... NW Italy to S Switzerland ...
While the vertical wind shear will remain rather weak, MLCAPE values from 1000 to 2000 J/kg will be sufficient for updrafts strong enough capable of some large hail events. Furthermore, heavy rainfall will be possible where storm interaction leads to some cells stalling over particular areas.
... Greece ...
MLCAPE values between 1000 and 2000 J/kg are forecast across the area with mean wind close to 0 m/s. Stationary pulse-like storms are forecast with threats of very heavy rainfall and large hail.
... central Russia ...
In an exit region of a jet-streak and along a diffuse cold front, storms will form in an environment of MLCAPE around 1000 J/kg and 0-6 km bulk shear of 15 to 25 m/s. Storm coverage is slightly different across the models in the area, but a Lvl 1 for severe wind gusts and large hail seems to be easily warranted.
... Caucasus ...
Some isolated large hail events will be possible in an environment featuring steep mid-tropospheric lapse rates and 0-6 km bulk shear of around 15 m/s
