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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 157 six-hour periods when the rainfall exceeded the threshold in 2016!

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):

030906 031906 041606 041612 041706 041806 041812 042706 042918 051612 051800 052300 052306 052412 052500 052512 052700 052706 052906 052912 053000 060206 060506 060706 061218 061306
061312 061412 061418 061500 061506 061518 062400 062612 070206 070306 070406 070512 070706 070712 070806 070906 070918 071006 071106 071200 071206 071218 071400 071406 071506 071706
071906 072006 072106 072400 072412 072606 072618 072706 072806 072918 073000 073012 073100 073112 080112 080206 080306 080318 080400 080506 080618 080806 080812 080918 081006 081012
081100 081106 081112 081118 081200 081206 081212 081300 081306 081312 081318 081506 081600 081606 081718 081806 081812 081906 081912 082006 082012 082018 082406 082412 082600 082606
082706 082900 082906 083000 083006 083012 090218 090300 090406 090412 090518 090806 090906 090912 091006 091106 091306 091406 091506 091600 091606 091618 091718 091806 091912 092200 092206 092306 092312 092400 092506 092518 092806 092900 092906 092912 093006 100406 100612 100700 100706 100806 100812 100818 100900 100906 101806 102012 102106 102200 102700 120612 122600

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.