*N < 10, see text 



(a) measurements given in inches 



Table 3. Wet season, dry season, and total annual precipitation for the 

 Everglades /Bay /Keys basin (adapted from Thomas 1974). 



thundershowers are related to cyclic 

 land-seabreeze convection patterns 

 and result in the majority of rain 

 occurring during the mid to late 

 afternoon hours, or when the peak 

 convergence is observed (Gruber 

 1969, Echternacht 1975). A temporal 

 shift in these diurnal patterns has 

 been noted along the eastern shore 

 and the coastal islands, including 

 the Florida Keys. Here, where the 

 convective activity is initiated 

 prior to moving inland, the daily 

 rainfall occurs during the early 

 morning hours (USDC 1981a, 1981b). 



Distribution of rainfall over 

 southern Florida during the wet 

 season follows a bimodal pattern 

 shown in Figure 10. The first of 



two peaks occurs in May or June and 

 the second during September and 

 October (Thomas 1974). This bimodal 

 seasonal distribution of rainfall is 

 associated with an upper air trough 

 which extends southwards from the 

 middle latitudes centering itself 

 over southern Florida during June. 

 It is displaced westwards into the 

 Gulf of Mexico during July and 

 August and returns again in Septem- 

 ber/October (Gruber 1969, Thomas 

 1970). Periods of heaviest rainfall 

 occur when this trough is overhead 

 (Riehl 1954). Although this bimodal 

 quality is characteristic of all the 

 basin stations, the late spring/ 

 early summer peak is less pronounced 

 in the Keys (Thomas 1970). 



27 



