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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 0932 UTC Thursday April 3 2025. (click image to embiggen)

The ten most recent TORFF overlapping warnings in 2024 are:

OHX issued TOR warning at: 202504030838 and FF warning at: 202504030808
OHX issued TOR warning at: 202504030833 and FF warning at: 202504030808
OHX issued TOR warning at: 202504030825 and FF warning at: 202504030808
OHX issued TOR warning at: 202504030754 and FF warning at: 202504030757
OHX issued TOR warning at: 202504030754 and FF warning at: 202504030808
MEG issued TOR warning at: 202504030747 and FF warning at: 202504030737
MEG issued TOR warning at: 202504030740 and FF warning at: 202504030737
OHX issued TOR warning at: 202504030736 and FF warning at: 202504030757
MEG issued TOR warning at: 202504030719 and FF warning at: 202504030737
MEG issued TOR warning at: 202504030719 and FF warning at: 202504030721

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.