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 1033 UTC Monday June 14 2021. (click image to embiggen)

The ten most recent TORFF overlapping warnings in 2021 are:

LZK issued TOR warning at: 202106100103 and FF warning at: 202106100129
LZK issued TOR warning at: 202106100103 and FF warning at: 202106100034
LZK issued TOR warning at: 202106100053 and FF warning at: 202106100034
LZK issued TOR warning at: 202106072057 and FF warning at: 202106072119
LZK issued TOR warning at: 202106072054 and FF warning at: 202106072119
LWX issued TOR warning at: 202106032253 and FF warning at: 202106032229
ABQ issued TOR warning at: 202105302315 and FF warning at: 202105302345
ABQ issued TOR warning at: 202105302017 and FF warning at: 202105302019
TSA issued TOR warning at: 202105280007 and FF warning at: 202105280037
OUN issued TOR warning at: 202105271814 and FF warning at: 202105271841

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

Maps of overlapping warnings from previous years:

Year: 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

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:

10 km Buffer 20 km Buffer 30 km Buffer 40 km Buffer 50 km Buffer

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

Select a Storm:

Ike (2008) Lee (2011) Isaac (2012) Matthew (2016) Harvey (2017) Irma (2017) Nate (2017) Florence (2018)

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