By Dr. John Neilsen-Gammon, Texas State Climatologist who writes in via email –
Based on my not-fully-vetted record compilation, Harris County Flood Control District gauge #110 just broke the all-time record for greatest 3-day total at a regular reporting station in the United States (outside of Hawaii).
The August 26-28 total is 36.80”, with 4.5 hours and about 2” still to come.
The previous record is from 1997 at Dauphin Island, Alabama, 36.14”. The record at any non-station remains 48” at Medina, Texas, August 1978, and the Hawaii regular reporting station record remains 48.75” at Honokane in 1942.
Total rainfall in 20,000 sq mi area over 72 hours, expressed as multiples of the average daily discharge of the Mississippi River (call them Mississippi-days), top United States storms:
14.8 Beulah 1967 TX/MX
13.9 1899 TX
13.2 Georges 1998 FL
12.6 1994 TX
12.6 Floyd, NC
12.0 1940 (May) LA
11.3 1940 (Nov) TX
10.1 2010 TN
9.7 Alberto 1994 GA
I will update this story with final data when it is available. -Anthony
UPDATE: (edited for clarity) Since writing in a couple of hours ago, the total has increased, here is the latest as of 8PM PDT today: 38.64″ for the three-day total. And, 40.76″ since Harvey started making rain 4 days ago.
UPDATE2: The final number for a 3 day total is: 41.64″. And, 43.76″ since Harvey started making rain 4 days ago. See updated graph below: