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Archive of past heavy precipitation events

Switch to a different threshold:

Select a year: 100 year, 6-hour recurrence interval

There were 84 six-hour periods when the rainfall exceeded the threshold in 2018!

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):

041500 051800 052112 052800 052900 052906 053000 060900 061306 061512 061518 061618 061706 061712 061900 061912 062006 062506 062700 062806 062906 070106 070200 070306 070312 070418
070500 071212 071306 071612 071812 071900 071906 071912 073106 081506 081518 081606 081618 081906 082006 082012 082100 082106 082118 082700 082712 082806 082812 083118 090100 090112
090306 090406 090506 090518 090700 090818 091006 091400 091406 091412 091418 091500 091506 091512 091518 091600 091606 091612 091700 091706 092006 092112 092118 092612 100812 101106
101118 101200 101206 101406 101612 122706

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.