The December 15, 2021 Derecho & Tornado Outbreak
The First Recorded December Derecho in the United States & Biggest Tornado Outbreak in NWS La Crosse History
Records
- Most tornadoes from one weather system in the NWS La Crosse forecast area
- First December tornado in the NWS La Crosse forecast area
- First December tornado in Minnesota
- First December Derecho documented in the United States
- Second strongest measured wind gust on record at both Rochester, MN (77 mph) and La Crosse, WI (68 mph)
- Second lowest sea-level pressure in December at Rochester, MN
- Most 75+ mph wind gusts for one event since at least 2004 in the United States
- Warmest December temperatures ever recorded in the region
- Latest calendar-year SPC moderate risk this far north
- First December tornado watch this far north
Watches and Warnings Issued
- 1 High Wind Watch (all counties)
- 1 High Wind Warning (all counties)
- 1 Dense Fog Advisory
- 1 Tornado Watch (all counties)
- 12 Severe Thunderstorm Warnings (Tags: 2@80mph, 7@70mph, 4@60mph)
- 8 Tornado Warnings
- 47 Severe Weather Statements
Statistics and Storm Reports
- Over 80 severe thunderstorm reports
- Thunderstorm wind gusts (measured):
- 60 mph or greater: 34
- 70 mph or greater: 18
- 80 mph or greater: 8
- Non-thunderstorm wind gusts (measured):
- 50 mph or greater: 33
- 60 mph or greater: 15
- 70 mph or greater: 1
- 27 tornadoes surveyed
- EF2: 4
- EF1: 14
- EF0: 9
- Severe Thunderstorm Warnings:
- 25 min average lead time for the first severe report in the warning
- 38 min average lead time for all warned reports
- Tornado Warnings:
- 6 min average lead time to the first tornado within a warning
- 13 min average lead time for all warned tornadoes