Monitoring of concurrent, co-located tornado and flash flood (TORFF) warnings
Below is the most recent image showing overlapping tornado and flash flood warning polygons thus far in 2024. Warnings are shown if they overlap in space and are valid within 30 minutes of one another, calculated as described in Nielsen et al. (2015, Weather and Forecasting). The images are updated once per day at approximately 1200 UTC. The images are zoomed in on the region where overlapping TORFF warnings are most frequently observed.
Images last updated 0931 UTC Wednesday April 24 2024. (click image to embiggen)The ten most recent TORFF overlapping warnings in 2023 are:
TAE issued TOR warning at: 202404102204 and FF warning at: 202404102141MOB issued TOR warning at: 202404101657 and FF warning at: 202404101715
LIX issued TOR warning at: 202404101453 and FF warning at: 202404101426
LCH issued TOR warning at: 202404101234 and FF warning at: 202404101222
LCH issued TOR warning at: 202404101211 and FF warning at: 202404101222
LCH issued TOR warning at: 202404101204 and FF warning at: 202404101222
LCH issued TOR warning at: 202404101117 and FF warning at: 202404101128
LSX issued TOR warning at: 202404020548 and FF warning at: 202404020603
LSX issued TOR warning at: 202404020543 and FF warning at: 202404020603
JAN issued TOR warning at: 202403260240 and FF warning at: 202403260306
Download the text file with the details of this year's overlapping warnings.
All TORFF Warning Intersections (n=4173) from 2008-2019:
Map of "Verified" TORFF Events from 2003-2018:
"Verified" TORFF events are identified by finding intersections between flash flood local storm reports (LSRs) and official tornado paths that were reported within three hours of one another, allowing for up to a 50 km spacing between the two. Five different spacing thresholds are tested from 10 km to 50 km, where the 10 km (50 km) spacing creates the most (least) conservative event totals. Between 25 and 75 "verified" TORFF events occur on average per year, depending on spatial threshold chosen. Discussion of the specific methods can be found in Nielsen (2019) and Henderson et al. (2020, Weather and Forecasting).
Select a Spatial Buffer:
TORFF Warning Intersections for Select U.S. Tropical Cyclones:
Select a Storm:This research is sponsored by NOAA grant NA15OAR4590233, in support of the 2016 VORTEX-SE field campaign.