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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 100 six-hour periods when the rainfall exceeded the threshold in 2015!

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):

040106 041306 042706 050506 050706 050906 051106 051812 052006 052400 052406 052800 052806 052900 052906 053006 060206 060306 060506 060706 060806 061100 061206 061406 061500 061706
061800 062000 062118 062318 062700 062900 070100 070112 070412 070506 070606 070612 070712 070800 070812 070818 070912 071006 071106 071206 071212 071312 071406 071606 071612 071800
071806 071906 072006 072100 072112 072200 072506 072618 072700 072706 073112 080106 080418 080600 080806 081500 081618 081706 081900 082306 082612 082806 082818 082900 083006 083106
090118 090218 090300 090506 091006 091106 092306 092400 092406 092606 093018 100300 100406 100412 100418 100906 102218 102318 102400 103018 112000 122418

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.