Broward/NE Miami-Dade Heavy Rainfall Event  May 27, 2003

On Tuesday evening, May 27, 2003, torrential rainfall fell over eastern Broward County from around the Pompano Beach area south across Oakland Park and Fort Lauderdale to Dania Beach and Hollywood. Over 10 inches of rain was measured at Fort Lauderdale Hollywood International Airport /10.21 inches/ for the 24 hour period from 7 AM on May 27 through 7 AM on May 28, shattering the old record of 3.10 inches for that date set in 1954. Most of the rain fall during a 4 hour period from 5 PM to 9 PM with 4.86 inches falling in one hour from 6 PM to 7 PM, and 7.36 inches falling in the two hours from 6 PM to 8 PM. This is very close or perhaps even exceeds the 100 year maximum expected rainfall for Southeast Florida for that time period. [ A 100 year maximum expected rainfall is that amount of rainfall that can be expected, on the average, to fall only once in a 100 year period. ]

Very heavy rain also fell over other parts of eastern Broward and northeast Miami-Dade counties. National Weather Service Doppler Radar estimated 10 to 12 inches of rain fell in a swatch from Hollywood to Pompano Beach with a few estimates of 12 to 14 inches near Dania Beach and Wilton Manors.

Click for graphic of NWS WSR-88D radar estimated rainfall

The total rainfall at Fort Lauderdale Hollywood International Airport for the month of May was 17.85 inches, which easily surpassed the old record May rainfall of 15.95 inches set back in 1958.

What caused so much rainfall in such a short time? As usual for exceptionally heavy rainfall events, it was caused by a combination of factors coming together in just the right way at the same time to cause a torrential downpour. The two most important ingredients were a weak tropical wave in the lower levels of the atmosphere that extended from the northwest Caribbean Sea into South Florida, coupled with a mid and upper level trough of low pressure in the eastern Gulf of Mexico. Precipitable water, a measure of how much water vapor is available in the atmosphere, was around 2 inches, and sea breeze circulations and above normal instability helped provide a trigger for the development of afternoon thunderstorms.

Heavy rainfall forecasting remains one of the biggest challenges in modern meteorology. While forecasting heavy rain per se is fairly straightforward, accurately forecasting WHERE the heavy rainfall will occur, WHAT TIME PERIOD it will occur within, and HOW MUCH rainfall exactly will fall are extremely difficult challenges for today's meteorologists.

LISTING OF SOUTH FLORIDA RAINFALL AMOUNTS FOR 24 HOURS ENDING AT 8 AM EDT WED. MAY 28, 2003

...HIGHEST TEMPERATURE YESTERDAY...LOWEST LAST 12 HOURS...
...PRECIPITATION LAST 24 HOURS...DATA AS OF 1200 UTC...