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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 95 six-hour periods when the rainfall exceeded the threshold in 2016!

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):

030906 041606 041706 041806 041812 042918 051800 052300 052306 052700 052706 052912 060206 060706 061218 061306 061312 061412 061500 061506 062400 062612 070406 070512 070706 070712
070806 071106 071200 071206 071218 071400 072400 072606 072618 072706 072806 073100 073112 080112 080206 080306 080318 080400 080506 080806 080812 081006 081100 081106 081112 081118
081300 081306 081312 081318 081506 081600 081606 081718 081806 081912 082412 082600 082900 082906 083006 090218 090406 090412 090518 090806 090906 091006 091106 091600 091606 091912
092206 092506 092518 092912 093006 100612 100700 100806 100812 100818 100900 100906 101806 102012 102106 102700 122600

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.