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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 42 dates where the rainfall exceeded the threshold in 2009!

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):

0329 0417 0418 0426 0427 0430 0509 0526 0527 0602 0616 0617 0619 0620 0621 0629 0704 0712 0716 0723 0808 0809 0814 0815 0816 0818 0820 0825 0827 0905 0908 0909 0912 0918 0921 0922 1009 1030
1112 1120 1215 1224

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.