Apart from long term trends in yearly precipitation, the most 
important characteristic of rainfall in the region is its pronounced 
seasonal distribution. A distinct wet season occurs from June through 
September during which approximately 60% of the total yearly 
precipitation falls (Figure 3). This summer wet season is the result of 
local sea-breeze/convection circulation patterns in which moist air from 
the Gulf moves inshore with daytime sea breezes and converges with 
convective air currents caused by the rapid heating of the land surface. 
Rainfall produced from this process generally occurs as brief 
thunderstorms (1-2 hrs) accompanied by strong winds. These thunderstorms 
occur most often during late afternoon or early evening hours, the period 
of maximum atmospheric convergence. One characteristic of these summer 
thunderstorms is the high spatial variation in rainfall. Due to the 
location and variable moisture content of different storm clouds, 
rainfall can vary markedly between stations of close proximity, and 
monthly variations of more than 5 inches have occurred in areas situated 
only a few kilometers apart. 
Average Monthly Rainfall 
Tampa & Bradenton Stations 
10-1 
9 - 
Period of Record 
8 - 
Tampa 1901-1986 
Bradenton 1911-1986 
7- 
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6 - 
111 
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| Bradenton Rainfall |J Tampa Rainfall 
Figure 3. Average monthly rainfall for the Tampa and Bradenton stations. 
21 
