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 2021. 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 1045 UTC. The images are zoomed in on the region where overlapping TORFF warnings are most frequently observed.

Images last updated 1131 UTC Saturday December 4 2021. (click image to embiggen)

The ten most recent TORFF overlapping warnings in 2021 are:

PAH issued TOR warning at: 202110250420 and FF warning at: 202110250441
PAH issued TOR warning at: 202110250413 and FF warning at: 202110250434
LSX issued TOR warning at: 202110250211 and FF warning at: 202110250212
PAH issued TOR warning at: 202110250203 and FF warning at: 202110250212
LSX issued TOR warning at: 202110250148 and FF warning at: 202110250212
LSX issued TOR warning at: 202110242217 and FF warning at: 202110242214
EWX issued TOR warning at: 202110140839 and FF warning at: 202110140842
EWX issued TOR warning at: 202110140819 and FF warning at: 202110140842
OUN issued TOR warning at: 202110110043 and FF warning at: 202110110025
TAE issued TOR warning at: 202110071145 and FF warning at: 202110071144

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.

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.