Breaking Weather News! A shower sat almost directly over PDX between 8:10 & 9pm…1.03″ rainfall fell in just 1 hour. That is the heaviest rain that has ever fallen in 1 hour at PDX! But 1-2 miles away the rain was far lighter. Talk about a freak event eh?
The previous record was set just 2 years ago with thunderstorms on Memorial Day Weekend. That was .93″ in one hour.
11pm Update:
Looks like we probably broke the record for 1/2 hour as well. As Brian up in Clark County points out…it appears that .96″ fell between 8:21 & 8:53pm. That would be .96″ in 32 minutes. The all-time 30 minute record is .82″ in August, 1968.
The short-term rainfall records are here: http://www.wrh.noaa.gov/pqr/pdxclimate/pg83.pdf
Chief Meteorologist Mark Nelsen
FOX 12 Weather Blog 
[Milwaukie] 9/8/2010
68.5°F High ◄▬ +0.1°/KORMILWA5; KORMILWA3 is stuck at 60.4
50.5°F Low
WNW 10.5 mph at 2:35p
Trace