Storm Forecast
Valid: Mon 11 May 2026 06:00 to Tue 12 May 2026 06:00 UTC
Issued: Sun 10 May 2026 22:58
Forecaster: PUCIK
A level 2 was issued across central part of N Italy mainly for large to very large hail, severe wind gusts and to a lesser extent tornadoes.
A level 2 was issued across NE Italy, W Slovenia and Istria mainly for heavy rainfall, tornadoes and to a lesser extent large hail.
A level 1 was issued for NW Italy mainly for large to very large hail.
A level 1 was issued for SE France mainly for heavy rainfall and large hail.
A level 2 was issued for E Croatia, N Bosnia, S Hungary and Serbia mainly for large hail, severe wind gusts and tornadoes.
A level 2 was issued for Bulgaria for large hail and severe wind gusts.
A level 1 was issued from Croatia to Romania and Bulgaria mainly for large hail and severe wind gusts.
A level 1 was issued from Austria through Czechia, central and north Hungary to Slovakia and Poland mainly for heavy rainfall. Tornado threat will be elevated to some degree from NE Slovakia to E Poland.
A level 1 was issued across Turkey and Caucasus mainly for large hail and heavy rainfall.
A level 1 was issued for central west Russia mainly for heavy rainfall.
DISCUSSION
... N Italy to Slovenia and Istria ...
A short-wave trough is forecast to cross the area during the day with synoptic-scale lift overspreading Piemonte in the late morning hours and shifting to NE Italy and Slovenia by 18 UTC. A cold front, located north of the Alps, is not expected to influence the region. Airmass will be characterized by specific humidity of around 10 g/kg combined with mid-tropospheric lapse rates of 7 to 7.5 K/km. MLCAPE values of 500 to 2000 J/kg are simulated with the highest values over Piemonte and just north of the Apennines.
Several mesoscale lift mechanisms will initiate storms during the forecast period. First, the orography is forecast to trigger storms, especially over the southern Alpine foothills. Second, a dryline boundary is forecast to establish north/northeast of the Apennines. Third, another dryline will push from the mountains in the evening over Piemonte. All of these will be able to trigger storms. Initiation will come last over the Piemonte region and will come first over the eastern half of northern Italy.
The first storms of the day will likely exist over Liguria, bearing the risk of heavy rainfall given strong onshore flow may repeatedly initiate more cells. ICON-D2 maintains mostly isolated convection inland and given presence of 15 to 25 m/s of 0-6 km bulk shear, supercells are expected to be a part of the convective storm type mix. From Piemonte into Lombardia, the main risks will be large to very large hail given substantial shear above 1 km and fat CAPE profiles above the -10 deg C isotherm. Straight hodographs may result in multiple storm splits and cell interactions, including a possibility of an upscale growth into small linear segment and an increase in the attendant severe wind risk. Severe wind and tornado risk will increase towards the Adriatic coastline with increasing shear in the lower troposphere, reaching up to 15 m/s in 0-1 km layer in the evening hours. However, rather straight hodographs may limit the tornado risk.
Further east, the coverage of storms may be greater and that will be especially over NE Italy and W Slovenia, where models suggest several waves of storms from morning into the evening hours. This may result in a serious risk of excessive rainfall event should cells train over the same location, repetitively triggered by local orography. Moister profiles and stronger low-level shear also point to higher risk of tornadoes. Currently, models are showing the best conditions for tornadoes over Istria with 0-1 km bulk shear up to 15 m/s and 0-500 m SRH exceeding 100 m2/s2.
... Adriatic coastline ...
Low resolution models parameterize convection across the Adriatic coastline in the late evening to night hours. Mesoscale lift mechanism will be the onshore flow combined with local orography. Storms will rapidly move across the "sweetspot" of CAPE belt and intense 0-3 km shear. Skinny CAPE profiles will limit hail risk, while it is uncertain if more cells will train over the same area. A mix of rain and wind risk is anticipated with the more intense storms.
... E Croatia, S Hungary through Serbia into W Romania and Bulgaria ...
A gentle synoptic-scale lift will overspread the area ahead of an approaching trough. At the surface, a subtle dryline boundary is forecast to move downslope of the Dinarides. Modest low-level moisture with specific humidity of 8 to 10 g/kg and lapse rates of 6.5 to 7 K/km will yield MLCAPE values around 1000 J/kg. Isolated initiation is forecast given the lack of widespread mesoscale lifting mechanism. Orography and the dryline will be responsible for the initiation and storms will spread into the lowlands with time. Moderately strong deep-layer vertical wind shear is forecast with 0-6 km values of 15 to locally over 20 m/s. Low-level shear and hodograph curvature are expected to increase from southern Hungary to NE Croatia and NW Serbia in the evening hours. However, it is possible that storms will already evacuate the area by that time.
Anyway, a mix of multicells and supercells is expected, with threats of large hail or even very large hail and severe wind gusts. If storms are still ongoing across S Hungary, NE Croatia and NW Serbia around 18 UTC, tornado risk will be present too. While the coverage of storms is uncertain at the moment, decided to introduce Level 2 for the areas that are at the highest risk of severe weather in the region.
... SE France ...
Cold front is expected to cross the region throughout the day. At first, some isolated storms may form ahead of it, still in the environment of MLCAPE around 1000 J/kg and 0-6 km bulk shear of above 20 m/s. There will be a short space for some multi to supercells capable of large hail. Soon afterwards, the cold front will undercut all the activity with storms developing on its cool side. More waves of storms may be triggered as the front stalls around the Alps with attendant heavy rain risk.
... Austria to Czechia, Slovakia, northern Hungary and Poland ...
The aforementioned cold front will rapidly sweep east across the area, initiating scattered to widespread storms throughout the day. Forecast profiles are rather unspectacular with skinny CAPE and 0-6 km bulk shear around 10 m/s. Moist profiles point to the main threat being heavy rainfall, especially if storms cluster along the local orography and the frontal zone. An exception to this will be an area of northeastern Slovakia to central Poland, where hodographs show enhanced curvature, 0-1 km bulk shear of up to 10 m/s and 0-1 km SRH of around 150 m2/s2. Stronger storms will bear enhanced tornado risk here.
... Turkey ...
A short-wave at 300 hPa will cross the region during the day, providing synoptic-scale lift. Forecast profiles are moist above LFC with about 1000 J/kg of MLCAPE. Moderately strong vertical wind shear is forecast with 0-6 km bulk shear of around 15 m/s. Scattered storms are forecast in the area with mesoscale lifting done by local orography. A combined risk of large hail and heavy rainfall is forecast.
