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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 2010!

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):

041700 050112 050118 050200 050212 050218 050400 051218 051418 051700 052206 052500 052506 052600 052618 052918 060100 060606 060906 060912 061012 061106 061218 061300 061306 061400
061406 061606 061706 062100 062112 062212 062306 062318 062506 062606 062706 070112 070400 070406 070412 070418 070500 070506 070512 070706 070800 070806 070818 071100 071106 071200
071400 071506 071600 071906 071912 072012 072106 072118 072206 072212 072306 072312 072412 072800 073006 080106 080206 080212 080806 081106 081312 081612 081618 081812 081818 081906
081912 082100 082118 082412 082506 082512 083106 090118 090212 090312 090418 090806 090912 091006 091106 091112 091918 092306 092512 093012 093018 100100 100106

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.