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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 133 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 051906 052112 052506 052900 052906 053000 060106 060200 060400 060900 060912 061006 061018 061306 061506 061512 061518 061618 061706 061712 061718 061812 061900 061912
062000 062006 062012 062100 062212 062400 062500 062506 062700 062806 062906 070106 070200 070300 070306 070312 070418 070500 070506 070518 071006 071012 071212 071306 071612 071812
071818 071900 071906 071912 072406 073106 080100 081218 081318 081506 081518 081606 081618 081906 082006 082012 082100 082106 082118 082406 082418 082700 082712 082806 082812 082906
083018 083118 090100 090112 090306 090406 090412 090506 090512 090518 090612 090700 090718 090818 090900 090906 091006 091106 091218 091400 091406 091412 091418 091500 091506 091512
091518 091600 091606 091612 091618 091700 091706 091712 091718 091818 092006 092106 092112 092118 092206 092518 092600 092612 100712 100812 101100 101106 101118 101200 101206 101406 101612 122706 122800

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.