Wednesday, December 16, 2009

New Orleans Doubles December Rainfall Record
3 Daily Records in 4 Days

Dec. 21 Update: After several days of drying out, the latest 5-day precipitation forecast (to the right) issued this morning from the National Weather Service/NCEP shows the Gulf Coast getting hammered again, and the forecast discussion from New Orleans indicates the likelihood of severe weather as well.

Noon Update: An additional 0.68" fell after midnight, raising the monthly total to 24.93", just 0.18" below the all-time record.

Baton Rouge also set a daily record with 2.41", exceeding the 2.35" in 1961.

The 13.14" through midnight at Mobile is a new December record, breaking the record which has stood since 1853. Unofficially, Mobile has received another 0.63" since midnight.

December 18 Update: A total of 1.77" on Thursday brings the New Orleans December rainfall to 24.25", within less than an inch of the all-time record for any month. The Thursday amount is a new daily record for December 18, the third time this has happened in the last 4 days. The old record was 1.46" in 1995.

Original post:
El Niño events tend to bring heavy rainfall to the southern U.S., including the Gulf Coast, and the current one is expected to be no different, but the first half of December has gotten off to a spectacular start. Aided by two consecutive record-breaking days, New Orleans Airport has doubled its previous December monthly rainfall record in just two weeks.

Monday's 3.28" broke the December 14 record of 2.04" set in 1976, and Tuesday's 5.70" almost doubled the daily record of 2.87" set in 1970. Halfway through the month, the December total of 22.48" is more than double the airport record of 10.77" set in 1977. It also exceeds the metro New Orleans December record of 14.43" in 1905. This is now the wettest month ever recorded at the airport since records began in 1947, easily surpassing the 21.18" in May 1995. The total is also within about 2.5" of the all-time New Orleans area monthly record of 25.11" mainly produced by a tropical storm in October 1937. Area records extend back to 1871.

The excessive rain has led to widespread street flooding in the New Orleans metro area.

The monthly rainfall so far of 12.70" at Mobile is the second wettest December total in records extending back to 1842. The record is 13.09" in 1853.

Images (click to enlarge): 5-day precipitation forecast through 6 am CST December 26, December precipitation departure from average through 6 am CST December 16, 5-day precipitation forecast through 6 am CST December 21, all from National Weather Service

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