High Risk Issued: Two-Day Severe Weather Outbreak Targets France, the Alps, and Central Europe

Severe weather outlook – forecast across Europe. This forecast features areas of organized severe weather with risk levels and severe weather threats across the European continent. SEVERE WEATHER OUTLOOK   Valid: 27/08/2026 06 UTC – 29/08/2026 06 UTC Issued by: Severe Weather Europe Forecaster: Marko Korošec SUMMARY   *** A significant two-day severe weather outbreak is forecast across portions of western Europe from Thursday through Friday night this week. Moderate to high instability and strongly sheared environments combine for widespread thunderstorm activity with large to giant hail, severe winds, tornadoes, and flash flood potential from Eastern France to western Switzerland and southwestern Germany on Thursday. Followed , northern Austria to the Czech Republic and southwestern Poland on Friday.***   A large and deep upper-level trough is emerging into western Europe, with a strong blocking High over the Mediterranean region. Between these large-scale features, a powerful southwesterly jet stream is providing ample wind shear, while the air mass beneath it is extremely humid. This outlook focuses on both Thursday’s and Friday’s evolution, when a significant severe weather event is forecast across eastern and southern France toward the Alps, Germany on Thursday, and Austria, the Czech Republic, and Poland on Friday. Robust thunderstorms are expected from Thursday afternoon through Friday evening. Above: Video animation of the convective storm’s development across Central Europe from Thursday through Friday night, August 27th and 28th, 2026. For this reason, HIGH + MDT risks have been placed across portions of France, Switzerland, Germany, the Czech Republic, and Poland, with highlighted areas where the most robust severe weather threat will develop on both days. The threat includes enhanced potential for severe damaging winds, flash floods, tornadoes, and very large to giant hail (6-10 cm or larger).   SYNOPTIC OVERVIEW   This week’s weather pattern over Europe shows the underlying risk to France on Thursday. As a strong upper-level ridge builds over the Mediterranean, Central Europe, and the Balkans, a deep wave over western Iberia creates a significant pressure and temperature gradient between the two large-scale features. This significantly amplifies southwesterly jet-stream winds from eastern Spain across the western Mediterranean into southern and eastern France, providing violent wind shear. This results in a frontal system entering France, with the cold front moving west to east towards Germany and the Alps from Thursday midday through Friday night. WEATHER FORECAST DISCUSSION – Thursday, August 27th +++ Weather forecast for France, Switzerland, and Germany +++   Explanations for abbreviations (TSTM, SLGT, ENH, etc.) Highlighted severe weather threats: Tornado potential: High Maximum hail size: More than 8 cm Peak wind gusts: Up to 120 km/h 24-hour rainfall: Up to 100 mm HIGH risk has been issued for east-central France, western Switzerland and southwestern Germany for an outbreak of severe thunderstorms.