Storm Forecast
Valid: Sun 09 Aug 2026 06:00 to Mon 10 Aug 2026 06:00 UTC
Issued: Sat 08 Aug 2026 20:08
Forecaster: PUCIK

A level 2 was issued from N Spain to SW France mainly for large to very large hail and severe wind gusts.

A level 1 was issued from N Spain to S France mainly for large hail and severe wind gusts.

A level 1 was issued across the Alps and Apennines mainly for excessive rainfall and large hail.

A level 1 was issued for the Caucasus region and NE Turkey mainly for excessive rainfall.

A level 1 was issued for SE Ukraine mainly for excessive rainfall.

DISCUSSION

... N Spain to SW France ...

Small mid to upper tropospheric low will advance towards the area from the Bay of Biscay, providing synoptic-scale lift and enhancement of mid-tropospheric flow. Towards the surface, an ill-defined frontal boundary in weak pressure gradient is simulated. Abundant lower-tropospheric moisture with 12 to 14 g/kg specific humidity and mid-tropospheric lapse rates of around 7 K/km will contribute to 1500 to 3000 J/kg of MLCAPE. Moisture and CAPE will decrease towards the northeast. Especially in the early afternoon hours, high LCLs are predicted.

Some storms may be ongoing over central France in the morning hours with isolated threat of large hail. Further initiation will be provided by local orography (especially Pyrenees) and later on also convergence zone on the frontal boundary moving over S France. Given 0-6 km bulk shear of around 20 m/s, well-organised storms, including supercells, are likely. Given rather straight hodographs, storm splitting is likely. Mesocyclone strength will be limited by low SRH values mostly below 150 m2/s2. Primary threat will be large to very large hail given fat CAPE profiles in the hail growth zone. Downbursts are possible too, especially early on with high LCLs and then perhaps in case that storms cluster in the evening hours into a short linear segment. Highest coverage is forecast in the late evening into early night hours with storms becoming elevated.


... Alps ...

Scattered storms are forecast to form in the early afternoon over the Alps. Given 10 to 15 m/s, some well-organised multicell clusters are likely with threat of local excessive precipitation and large hail in stronger updrafts.

... Apennines ...

Stationary storms are forecast to form over the Apennines with primary threat being heavy rainfall leading to local flash floods. Stronger updrafts may result in large amounts of small to marginally large hail accumulating in a single location.