National Weather Service United States Department of Commerce

The development of daily Florida summer thunderstorms are the result of interactions between the larger scale (synoptic) wind flow in the lower levels of the atmosphere, and the various smaller scale sea-breezes, lake-breezes, and river-breezes, which form daily across the state. These individual boundaries can force thunderstorms on their own, however, thunderstorm development is favored where the large scale flow opposes these boundaries (enhanced convergence), and unstable air is forced to rise, feeding greater thunderstorm development.

The large-scale wind patterns during the summer months are determined by the position and strength of the Atlantic subtropical ridge. The subtropical ridge is a semi-permanent area of high pressure that resides roughly at the latitude of 30 degrees in the northern Hemisphere. As the subtropical ridge axis migrates north and south with respect to 30 degrees north, the wind patterns over the Florida peninsula will change. These changing wind fields also change the favored areas for thunderstorm development, both spatially and temporally.

Based on the common patterns of the subtropical ridge, meteorologists at the National Weather Service Forecast Office in Ruskin, FL identified eight wind patterns or "Flow Regimes" and produced high resolution spatial and temporal probability of precipitation (PoP) climatologies for each across the Florida peninsula, spanning the years 2002-2016. Climatologies were created at a spatial resolution of 2.5 x 2.5km, and temporally at 12, 6, 3, and 1 hourly. Using this data, forecasters are better able to refine rainfall forecasts at each location during the summer, to not only better pinpoint the most likely areas to see rain on a given day, but also when that rain is most likely to occur. In this website, these common variations of the subtropical ridge position, and the resulting rainfall patterns across the Florida peninsula are shown.

Below are the 12 hour, 800 AM through 800 PM EDT, rainfall probabilities for each of the regimes. For greater details on each flow pattern and the resulting thunderstorm evolution through the day, click on the individual flow regime numbers at the top of the page. For information of how this study was conducted, including datasets used, go to the Methodology tab.
All images on this page can be magnified by clicking, and resized back to original size with a second click.
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