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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 129 six-hour periods when the rainfall exceeded the threshold in 2002!

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):

030312 030906 040806 041412 041600 041900 042600 042718 050100 050318 050506 050600 050606 050806 051200 051600 052406 052900 053100 053112 060300 060400 060406 060500 060900 060906
060912 060918 061006 061018 061412 061518 061800 061812 062206 062212 062306 062312 062400 062406 062506 062706 062912 063018 070112 070118 070212 070218 070300 070312 070412 070506
070518 070612 070618 070718 070812 071006 071012 071018 071106 071800 071812 071906 071918 072200 072300 072306 072400 072606 072712 072912 073112 080200 080400 080406 080600 080606
080712 080718 081200 081206 081306 081406 081518 081606 081800 081912 082106 082206 082212 082306 082618 082700 082706 082712 082806 082900 083100 083106 090106 090200 090600 090612
090706 090712 090906 091000 091400 091406 091418 091506 091512 091600 091818 092212 092218 092318 092500 092618 092712 100906 101100 101112 101118 101318 101700 102918 112112

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.