Storm Forecast
Valid: Thu 16 Jul 2026 06:00 to Fri 17 Jul 2026 06:00 UTC
Issued: Wed 15 Jul 2026 21:28
Forecaster: PUCIK
A level 3 was issued for parts of S and SE France (Massif Central region towards the Alps) for very large hail and severe to extremely severe wind gusts.
A level 2 was issued from S France to Switzerland, N Italy and SW Germany mainly for large to very large hail and severe to extremely severe wind gusts.
A level 1 was issued across N Spain mainly for large hail and severe wind gusts.
A level 1 was issued across NW to central France mainly for heavy rainfall and large hail.
A level 1 was issued across N Germany mainly for heavy rainfall and marginally large hail.
A level 1 was issued across the Carpathians mainly for heavy rainfall and large amounts of marginally large hail.
A level 1 was issued across the Dinaric mountains mainly for large hail and severe wind gusts.
... S France to S Germany, Switzerland and N Italy ...
Another potentially high-end severe weather situation is forecast. Within the warm sector ahead of a weak and diffuse frontal boundary, ample low-level moisture is forecast to overlap with mid-tropospheric lapse rates exceeding 7 K/km, resulting in MLCAPE values ranging from 1500 to 4000 J/kg, with the highest CAPE forecast over S France and N Italy. Synoptic-scale lift will be mildly present in the form of an exit region of a jet-streak that will be over central and eastern France. Mesoscale lift will be provided primarily by orography and diffuse low-level boundary. Strong vertical wind shear is forecast across the whole area and given its overlap with moderate to high CAPE, a high conditional probability of (extremely) severe weather exists with stronger supercells and possibly also bow echoes. The belt of severe weather can be subdivided into:
-> Pyrenees and adjacent southern France
Some high-resolution models show little activity over this area. However, given a combination of orographic and frontal lift, albeit weak, there is a decent chance of storms forming especially towards the evening hours. Expect large to very large hail and severe wind gusts with any sustained storm. It is likely that the activity will be elevated on the cool side of the boundary.
-> Massif Central to Switzerland
This is the most likely corridor of storms, highlighted by all the models that were consulted. ICON-D2 EPS shows a high probability of supercells in this region. Some high-resolution models show an upscale growth of storms starting over Massif Central first as supercells in the afternoon and arriving to Switzerland as a convective system, perhaps a bow echo. Such system could easily travel across the Alps towards Austria. Depending on the convective mode, the main threat would be either very large hail or damaging wind gusts. In the southern Massif Central area, forecast soundings show around 3000 J/kg of MLCAPE combined with 15 m/s of 0-3 and 30 m/s of 0-6 km bulk shear. Given fat CAPE profile in the hail growth region, expect any supercell to easily deliver hail 5 - 10 cm in diameter. As storms progress east, higher LCL environment with steep lapse rates near the ground will drive damaging wind gust risk. Especially with potential upscale growth, swath of wind gusts exceeding 30 m/s would be possible. Second round of storms would be possible in the night hours in case the storms initiate further southwest, also bearing severe weather risk. A level 3 is placed in the area, where the highest confidence in a track of intense supercells is.
-> Border region Germany/France/Switzerland
A mix of left- and right-moving supercells is simulated in this area with severe weather threat increasing towards the higher CAPE environment in the south. Large to very large hail and severe wind gusts will be possible with stronger, especially right-moving supercells. An interaction of left- and right-movers may locally lead to clustering and upscale growth into linear segment.
-> N Italy
Compared to the previous day, it is less certain how many storms will cross the area. The most likely scenario is that some of the longer lived supercells that form over the Massif Central will move here and continue producing swaths of destructive hail and wind gusts. Environment will be similarly favorable as over Massif Central with MLCAPE above 2000 J/kg and 0-6 km bulk shear up to 30 m/s. The most likely pathway will be hugging the S Alpine range, but some models do suggest a lonely storm latching on the Apennines towards the evening. A second round of storms in the middle of the night is possible, too and will also bring severe weather risks, even though less compared to the late afternoon/evening storms.
... NW Spain ...
A well defined convergence zone together with orography is forecast to initiate scattered storms that will move from the land to the sea. Given 0-6 km bulk shear of around 20 m/s, increasing from west to east, some of the storms may deviate to the right and stay in a narrow belt of higher CAPE close to the convergence zone. In such case, a longer swath of large hail and severe wind gusts would be possible. Whether this happens is questionable and thus no lvl 2 was introduced in this area.
... NW France ...
Slow moving storms are forecast to form in an environment of abundant MLCAPE with threat of excessive rainfall and also locally large hail. The threat of hail and wind gust will increase towards the east with increasing shear.
... N Germany ...
A diffuse convergence zone will support isolated to scattered convective initiation, as shown by the NWP with storms spreading towards the sea. While severe weather risk will not be too high, an isolated heavy rainfall event or marginally large hail are not ruled out given 0-6 km bulk shear of around 15 m/s. Such shear may sustain some storm organization.
... Dinaric mountains ...
Isolated to scattered storms will form over the mountains and spread southeast during the day. With MLCAPE around 1000 J/kg and 0-6 km bulk shear of 15 to 20 m/s, expect a mix of multi to supercells capable of large hail and severe wind gusts.
... Romania ...
Slow moving storms capable of very heavy rainfall are forecast across the Carpathians. Low LCLs and deep warm cloud depth will promote efficient warm rain processes. Marginally large hail may occur with the strongest updrafts, though this threat should be secondary. If anything, large accumulations of small hail from slow moving storms may pose the greatest hail-related risk.
