Wednesday, December 7, 2011

Rainfall Sets Mid-Atlantic Records;
Update: Wettest December Day in History

1 AM Update: The final record-breaking total daily rainfalls:
Washington National 3.10" (1.34", 1971)
Washington Dulles 2.14" (1.13", 1976)
Baltimore/BWI 2.38" (1.27", 1976)
The Washington National amount exceeded the normal monthly precipitation of 3.05" for December.

10 PM Update: With 0.14" more rain in the past hour, the daily total is unofficially over 3" for the first time in ANY MONTH from November through March! Here are the previous daily records for each month:
Nov 2.95" 1943
Dec 2.81" 1977
Jan 2.77" 1915
Feb 2.29" 1896
Mar 2.79" 1881
9 PM Update: Washington National has now had just under 1" of additional rainfall since 4 pm, bringing the total to 2.91". This is now unofficially the wettest December day since precipitation records began in 1871, exceeding the old record of 2.81" on December 18, 1977.

Original post:
Cold-season precipitation extremes tend to be lower than those in warmer seasons because cold air holds less moisture than warm air. With heavy rainfall still falling, however, daily precipitation records for December 7 have already been set as of 4 pm in the Mid Atlantic area. Current totals (old records in parentheses):
Washington National 1.93" (1.34", 1971)
Washington Dulles 1.33" (1.13", 1976)
Baltimore/BWI 1.18" (1.27", 1976)
Note: The Baltimore record was easily exceeded by the 0.54" which fell in the next 3 hours.

1 comment:

Anonymous said...


Was this similar to the rains that we got in September. Back then, it seemed like a train of rain was funneled from the Carribean area and it just pounded the DC area. Now, just from looking at the radar, the same thing happen but the moisture came from the gulf coast from Lousiana/Texas.

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