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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 98 six-hour periods when the rainfall exceeded the threshold in 2019!

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):

040718 041912 041918 050200 050600 050706 050800 050806 051706 052900 053000 060412 060512 060518 060600 060606 060700 060712 060806 060918 061218 061700 062506 062712 062800 062812
062912 063006 063012 070112 070412 070506 070700 070706 070900 070906 071000 071006 071212 071500 071506 071512 071518 071612 071618 071806 072000 072012 072018 072200 072218 080106
080112 080212 080218 080712 080812 080918 081006 081200 081212 081300 081306 081600 082012 082406 082412 082506 082600 090112 090406 090612 091006 091106 091206 091218 091406 091812
091906 091912 091918 092000 092100 092106 092500 092800 092806 092918 100206 100312 102506 102606 103012 103018 103106 111006 122706 123106

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.