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Archive of past heavy precipitation events

Switch to a different threshold:

Select a year: 50 year, 6-hour recurrence interval

There were 105 six-hour periods when the rainfall exceeded the threshold in 2004!

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):

020606 032612 040406 040412 040506 042006 050906 051200 051206 051300 051306 051318 051600 052206 052306 052318 052906 053006 060706 060718 060906 060912 060918 061000 061106 061300
061406 061606 061906 062000 062112 062700 062706 062712 063006 070200 070406 070506 071112 071300 071306 072100 072500 072512 072518 072700 072818 072900 072906 072912 080212 080300
080306 080312 080506 080806 081506 081512 082306 082318 082406 082518 082606 082612 082706 082800 082806 082900 082918 083000 083100 090518 090706 090812 090906 090912 091506 091612
091700 091706 091712 091718 091806 091812 092200 092612 092700 092706 092806 100100 100106 100512 100606 101512 101912 102300 110206 112106 112112 112118 112406 112906 112912 120112
120718

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.