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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 90 six-hour periods when the rainfall exceeded the threshold in 2008!

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):

033018 051012 052212 052306 052318 052606 060506 060600 060706 060712 060718 060806 061306 061400 061900 062300 062406 062706 062900 062906 062912 070300 070306 070700 070706 071700
071800 071900 071906 072300 072306 072312 072318 072400 072406 072506 072618 072706 072712 072812 072912 073106 080300 080312 080606 080612 080912 081012 081100 081112 081200 081206
081400 081500 081818 081906 082000 082206 082218 082318 082400 082412 082718 082800 082806 090212 090218 090312 090612 090618 090706 090712 090900 091012 091106 091200 091206 091212
091218 091312 091318 091412 091418 092506 092706 092800 100706 101018 102000 111412

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.