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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 110 six-hour periods when the rainfall exceeded the threshold in 2007!

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):

031206 031500 042500 042712 042918 043012 050506 050606 050700 050706 050718 052118 052206 052400 052406 052506 052906 053000 060306 060400 060412 060706 060712 061006 061112 061200
061206 061300 061400 061406 061612 061618 061700 061812 062006 062112 062200 062206 062212 062300 062306 062512 062612 062618 062706 062712 062718 062800 063006 070306 070406 070412
071000 071212 071806 071812 072112 072118 072212 072306 072312 072706 072712 072900 072912 072918 073012 073112 080300 080318 080400 080406 080512 080718 080800 080806 080906 081506
081700 081706 081712 081800 081806 081812 081818 081906 081912 082000 082006 082012 082018 082112 082206 082218 082406 090412 090700 090706 090718 090800 090812 090818 090906 090912
091906 092118 100312 100418 100800 101612

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.