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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 101 six-hour periods when the rainfall exceeded the threshold in 2013!

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):

021106 041800 050800 051100 051800 051912 052512 052518 052606 052612 052706 052900 053006 053012 053112 060106 060112 060600 060800 061306 061506 061606 062012 062100 062106 062112
062212 062306 062318 062412 062418 062606 062612 062700 062706 062718 062800 062806 062906 070112 070200 070418 070500 070506 070706 070712 070818 071100 071206 071212 071306 071312
071506 071800 072006 072012 072112 072206 072612 072712 073000 073006 080206 080612 080712 080718 080806 080812 081100 081418 081500 081512 081612 082606 082800 082806 082818 083106
090100 090806 090812 091212 091218 091918 092000 092018 092106 092906 092912 100312 100412 100506 101118 101312 101318 101400 101406 103106 103112 103118 121112

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.