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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 2025. 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 1034 UTC Sunday January 19 2025. (click image to embiggen)

The ten most recent TORFF overlapping warnings in 2024 are:

LCH issued TOR warning at: 202412270321 and FF warning at: 202412270319
LCH issued TOR warning at: 202412270258 and FF warning at: 202412270229
LCH issued TOR warning at: 202412270258 and FF warning at: 202412270319
LCH issued TOR warning at: 202412270238 and FF warning at: 202412270229
LCH issued TOR warning at: 202412270234 and FF warning at: 202412270229
HGX issued TOR warning at: 202412262302 and FF warning at: 202412262302
HGX issued TOR warning at: 202412262256 and FF warning at: 202412262302
LCH issued TOR warning at: 202412262249 and FF warning at: 202412262302
SGF issued TOR warning at: 202411050055 and FF warning at: 202411050032
SGF issued TOR warning at: 202411050051 and FF warning at: 202411050032

Download the text file with the details of this year's overlapping warnings.


Maps of overlapping warnings from previous years:

Year:

RT_2023_map_current.png

All TORFF Warning Intersections (n=4173) from 2008-2019:

TORFF_WI_2008_to_2019.png

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:


50km_TORFF_events_2003_2018_Hawaii.png

TORFF Warning Intersections for Select U.S. Tropical Cyclones:

Select a Storm:

Harvey_TORFF_WI_All_BT.png

This research is sponsored by NOAA grant NA15OAR4590233, in support of the 2016 VORTEX-SE field campaign.


DISCLAIMER: The images and data on this site are intended for meteorological education and research purposes and, although they should generally be up to date, are not monitored at all times. Do not use for making decisions where money or lives are at stake. For official forecasts and warnings, visit the National Weather Service.