Replay · TO20211210
Quad-State tornado outbreak: the story
Dec 10, 18:00 UTC – Dec 11, 12:00 UTC. Radar, severe thunderstorm and tornado warnings, storm reports and ground stops, in order, with 497 links that show their evidence.
- 472 NWS warnings
- 618 storm reports
- 1 FAA airport programs
- 67 surveyed tornado tracks
- 497 rule-based links
- 137,862 customers out at the peak, in Tennessee
- 541 radar frames
Chapter 1: Watches
Dec 10
By mid-afternoon, NWS Paducah, Little Rock, Memphis and St. Louis have Tornado Watches in effect.
Chapter 2: First warnings
Dec 10–11
- NWS Paducah, KY issues the first Tornado Warning.Replay from here
- The largest hail reported: 2 in at Bogata, TX.Replay from here
Chapter 3: Mayfield
Dec 11
- NWS Memphis, TN declares a tornado emergency.Replay from here
- The strongest tornado, an EF4, touches down: a 166 mi track.Replay from here
- The strongest measured gust: 107 mph at 4 NNE Wingo, KY.Replay from here
- NWS Paducah, KY declares a tornado emergency.Replay from here
- NWS Paducah, KY declares a tornado emergency.Replay from here
- NWS Paducah, KY declares a tornado emergency.Replay from here
- NWS Paducah, KY declares a tornado emergency.Replay from here
- NWS Paducah, KY declares a tornado emergency.Replay from here
- NWS Paducah, KY declares a tornado emergency.Replay from here
Chapter 4: Overnight
Dec 11
- Peak outages: 137,862 customers out of power in Tennessee. The most in one county: Davidson County, TN, 83,500 out (23% of its customers) at 11:45 UTC.Replay from here
How we link records
| Rule | What it checks | Links |
|---|---|---|
| R4 solid | A storm report inside a warning polygon while it was in effect | 465 |
| R6 solid | A surveyed tornado track that began inside a Tornado Warning, with the warning's lead time | 32 |
Solid lines mark rules that passed an independent check; dashed lines are context. Links are rule-based facts: each shows two records that overlap in place and time. How we know
Where this storm's data comes from
Every layer, the provider behind it and the period it covers.
| Layer | Provider | Period | Records |
|---|---|---|---|
| MRMS SeamlessHSR | NOAA/NSSL via Iowa Environmental Mesonet | Dec 10, 18:00 UTC – Dec 11, 12:00 UTC | 541 |
| NWS storm-based warning polygons | NOAA National Weather Service via Iowa Environmental Mesonet | Dec 10, 18:00 UTC – Dec 11, 12:00 UTC | 472 |
| NWS Local Storm Reports | NOAA National Weather Service via Iowa Environmental Mesonet | Dec 10, 18:00 UTC – Dec 11, 12:00 UTC | 618 |
| FAA airport programs (ground stops and ground delay programs) | FAA Air Traffic Control System Command Center | Dec 10, 18:00 UTC – Dec 11, 12:00 UTC | 1 |
| ORNL EAGLE-I | Oak Ridge National Laboratory | Dec 10, 18:00 UTC – Dec 11, 12:00 UTC | 686 |
- Radar: NOAA/NSSL MRMS SeamlessHSR, via the Iowa Environmental Mesonet (IEM), Iowa State University
- Warnings: NOAA/NWS, storm-based polygons via the Iowa Environmental Mesonet
- Storm reports: NOAA/NWS Local Storm Reports via the Iowa Environmental Mesonet
- Airport programs: FAA Air Traffic Control System Command Center
- Tornado tracks: NOAA/NWS Damage Assessment Toolkit damage surveys
- Power outages: Oak Ridge National Laboratory, EAGLE-I (CC BY 4.0)
- County boundaries: U.S. Census Bureau
