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Archive of past heavy precipitation events

Switch to a different threshold:

Select a year: 50 year, 24-hour recurrence interval

There were 51 dates where the rainfall exceeded the threshold in 2015!

Hover mouse over a date to see the map (dates are listed as two-digit month followed by two-digit date, so that 0501 indicates May 1st):

0413 0505 0507 0510 0511 0520 0524 0528 0602 0612 0616 0617 0620 0622 0625 0704 0706 0707 0708 0709 0712 0714 0716 0722 0729 0731 0805 0806 0815 0817 0823 0826 0829 0903 0906 0924 0926 0930
1003 1004 1005 1009 1022 1023 1024 1025 1026 1224 1226 1227 1228

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.