Wednesday, June 10, 2009

Tuesday's Twin Thunderstorms: DC's Double Dose of Downpours
June Rainfall Ahead of Last Year's Pace

Images (click to enlarge): CapitalClimate chart of 2009 vs. 2008 monthly precipitation from National Weather Service (NWS) data, 24-hour precipitation amounts and 60-day percentage of average precipitation ending at 8 am June 10 from NWS

June 11 Update: Note that the Dulles record for June 10 was particularly vulnerable, since it was one of only a handful of June days with records below 1". The remaining ones are:
June  8 0.96"
June 9 0.66"
June 14 0.91"
June 23 0.48"
The all-time June daily record is 10.67" on June 21, 1972.

Midnight update: Additional daily amounts for Wednesday, June 10:
Washington National 0.48"
Washington Dulles 1.16" (1.04" in the hour ending 10 pm)
Baltimore (BWI) 0.15"
As of Tuesday's total, Washington National was already above the long-term average for the entire month of June. Wednesday's amount at Dulles was a new daily record for June 10, exceeding the 0.83" in 1963, the year the airport first opened. The year-to-date total at Dulles of 25.21" is now ahead of last year's near-record pace and nearly 40% above average.

Original post:
Tuesday's early morning and afternoon rush hour rounds of thunderstorms have added to the growing 2009 precipitation excess in the Washington-Baltimore region. Daily/monthly/year-to-date rainfall totals through June 9 are:
Washington National 0.89"/3.48"/20.75"
Washington Dulles 0.24"/4.27"/24.05"
Baltimore (BWI) 0.37"/2.74"/22.02"
Despite a droughty debut, the year is now 3.73" above average at Washington National. For the first month since January, June's total is now running over an inch above 2008's near-record rainfall rate.

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