Flood waters are receding in the rain-drenched Florida Panhandle and coastal Alabama today, where prodigious rains from a moist, tropical airmass interacting with a stalled front brought flooding that caused at least $20 million in damage to the Pensacola, Florida area. The most remarkable rains fell in West Pensacola, where 21.70″ was recorded over the weekend. Pensacola airport received 13.13 inches of rain on Saturday, the city’s second-highest 1-day rainfall total in recorded history. The only greater 1-day rainfall occurred on October 5, 1934, when Tropical Storm Nine brought 15.29″ of rain to the city. Satellite loops of atmospheric precipitable water show that this weekend’s heavy rains were caused by a flow of very moist tropical air that originated over the warm waters of the tropical Eastern Pacific and flowed northwards across Mexico and Central America to the Panhandle of Florida. This moist airmass has been replaced by relatively dry air over the Gulf, which should limit rainfall amounts today to the 1 – 2 inch range. A cold front expected to arrive on Tuesday will serve as the focus to bring additional rains of 1 – 2 inches per day to portions of the region Tuesday and Wednesday. Before this weekend’s mighty rainstorm, the Florida Panhandle was experiencing severe to extreme drought, with 12 – 15 inches of rain needed to pull the region out of drought. This weekend’s rains have busted the drought the extreme western Panhandle, but surrounding regions of Alabama, Georgia, and Florida still need 10+ inches of rain.

Figure 1. Radar-estimated rainfall for the Florida Panhandle from this weekend’s rain storm.

Figure 2. Amount of precipitation needed to bust drought conditions over the U.S., as of June 2, 2012. A Palmer Drought Severity Index (PDI) of -0.5 is considered the boundary of where a drought exists. The 12 – 15 inches of rain that fell across the extreme western Florida Panhandle and coastal Alabama over the weekend were enough to bust the drought in those regions. Image credit: NOAA Climate Prediction Center.

Some rainfall amounts from the storm, from 7 pm CDT Thu June 7, through 3 am CDT Sunday June 10, from the latest NOAA Storm Summary:

…ALABAMA…
TILLMANS CORNER 4.3 WNW 10.77″
GRAND BAY 0.6 NW 10.03″
MOBILE DOWNTOWN ARPT 8.97″

…FLORIDA…
WEST PENSACOLA 10.9 SW 21.70″
PENSACOLA RGNL ARPT 15.08″
MILTON 10.9 SSW 14.42″
PENSACOLA 3.8 N 13.88″
JACKSONVILLE 11.6 ENE 4.31″

…GEORGIA…
AUGUSTA/DANIEL FIELD 4.08″
WARNER ROBINS AFB 1.95″
VALDOSTA RGNL ARPT 1.50″

…LOUISIANA…
PONCHATOULA 11.8 E 5.64″
SLIDELL 4.29″
LACOMBE 1.4 N 3.73″
BATON ROUGE 2.5 E 2.26″
NEW ORLEANS/LAKEFRONT 2.13″

…MISSISSIPPI…
PASCAGOULA 7.50″
GULFPORT-BILOXI 6.52″
PASS CHRISTIAN 3.5 NE 4.69″

The Atlantic is quiet
There are no threat areas to discuss in the Atlantic today. The NOGAPS model is predicting formation of a strong tropical disturbance capable of becoming a tropical depression in the Western Caribbean by Sunday, but none of the other models is going along with this idea. We could get something developing in the waters offshore of North Carolina late this week, along the edge of a cold front expected to move of the U.S. East Coast on Tuesday – Wednesday. The GFS model has suggested something could develop in this region in several of its recent runs.

Jeff Masters