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Archive of past heavy precipitation events

Switch to a different threshold:

Select a year: 100 year, 6-hour recurrence interval

There were 70 six-hour periods when the rainfall exceeded the threshold in 2017!

Hover mouse over a date to see the map (dates are listed as two-digit month, then two-digit date, then two-digit hour so that 050112 indicates the period ending at 12 UTC on May 1st):

040412 042906 042918 043000 043006 043012 052000 052500 061200 061300 061406 062306 062312 062318 062906 063006 070512 070612 070812 071106 071118 071206 071212 071318 071500 072006
072012 072206 072306 072312 072712 072812 080112 080200 080400 080606 081300 081306 081312 081506 081512 081606 081806 081900 081906 082212 082606 082612 082706 082712 082800 082900
082912 083006 083012 083100 090100 090106 090112 091106 091118 092006 092106 092112 092606 092706 092718 100418 100512 103012

Data sources and notes:
Gridded recurrence interval data were provided by The Automated Geospatial Watershed Assessment Tool website.
That is based on data in Hershfield, D. M., 1961: Rainfall frequency atlas of the United States. U.S. Weather Bureau Technical Paper 40, 115 pp.
Precipitation data is the Stage IV analysis over the US, obtained in real-time from NOAA/NCEP.
Archived precipitation data come from NCAR/EOL.
The Stage IV analysis data have been coarsened slightly for this analysis, to a grid with approximately 8.25-km horizontal spacing. We have found that this helps to eliminate the identification of spurious events, although it may also remove legitimate events that occurred at very small spatial scales.
Currently, the analysis has only been conducted for states east of the Rockies, but we hope to extend it to the full US (using updated recurrence interval information where available) in the future.
Maps of events exceeding the 1-hour precipitation thresholds are not yet available, but we hope to post them soon.

Acknowledgments:
Stephanie Stevenson (undergraduate researcher at Texas A&M University) created the archived images (for the years 2002--2010) and performed most of the data analysis.
This work was published in Stevenson and Schumacher (2014, Monthly Weather Review). Please cite this paper if you make use of the data or analyses from this website in your own research.
This material is based upon work supported by the National Science Foundation under Grant Nos. AGS-0954908 and AGS-1157425. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.