Mesoscale Discussion
Valid: Mon 19 Oct 2026 19:00 to Tue 20 Oct 2026 03:00 UTC
Issued: Mon 19 Oct 2026 18:52
Forecaster: TUSCHY

This Mesoscale Discussion (MD) was issued to update the evolving severe risk along the Cevennes and S. The MD's validity does not match the timing of the severe risk, which lasts all night long.

Latest observations show a persistent E/SE-erly BL flow into a gradually structuring surface low atop the far W Gulf of Lion/NE Spain. This strengthening moisture flux serves as focus for repeated CI of northward moving thunderstorms into the MD area. For tonight, a rather steady 40kt LLJ from the S remains in place, which assists in effective IVT values during the night hours. TPWs exceed 200% to the background climatology and forecast soundings show deep warm cloud layers, skinny CAPE and lots of moisture in the troposphere.

The currently still progressive cell motion should turn into back-building mode around midnight onwards with further improving LL convergence along the E fringes of the structuring depression. A N-S aligned band of DMC with extreme rainfall amounts is forecast to evolve somewhere within the MD area, which could produce hourly rainfall amounts in the 60-100 mm range. Confined swaths of 250-400 mm in less than 12h are forecast. Flooding/flash flooding is likely and a few significant events cannot be ruled out.

Along the coasts, a few tornadoes are possible and this is also valid outside of the MD (e.g. along most of the coasts of France and far NE Spain).

Beyond 06Z, the MCS starts to shift E, which is in line with the attendant surface low.