How Many Gallons Of Rain Fell?

Imagine laying down a tarp over Duval county to collect every drop of rain that fell this afternoon. How many one gallon buckets of water would the storms fill?

Let's figure it out. One inch of rain over a square acre will fill up 25,154 gallon buckets. Or if the inch of rain fell over 1 square mile it would fill 17,380,000 gallons.

Jacksonville is 757 square miles or 484,480 acres big. By multiplying 17.38 million gallons of rain by 757 miles equals 13,156,660,000 gallons of water over Jacksonville for each inch of rain.

This image shows radar estimates for rainfall over the past 3 days.  Duval has orange and red colors showing rain of 5 to 9 inches.  So based on an average of 7.5 inches of rain, the total amount of rain that fell over the past 3 days in Duval equals 98,674,950,000 gallons of water.
Not all the rain soaks into the ground. Runoff from impervious surfaces like roads, parking lots, and thick clay soil reduces the amount of rain that sinks down to the aquifer.  Our flood warnings represent areas where the ground is not absorbing the rain.

OVERRUNNING MEANS A DAMP SATURDAY

A wedge of shallow heavier cool air is moving in behind a cold front Thanksgiving evening. We will notice drier and cooler weather Friday. But rain is in the forecast Saturday as warm air tries to move back north. This overrunning will result in mostly cloudy skies and light showers increasing through the afternoon. This .gif file from the University of Illinois shows the process. Assume Point A is Miami and B is Jacksonville.



Overruninng is the result of a physical process of isentropic lift: Warmer air (point A) is moved northward due to large scale lifting weather systems. Typically this is due to spinning pockets of air at 18,000 ft. Bends or dips in the Jet stream impart the spin to the vorticity maxims. Warm air is lighter and rides over denser colder air (point B). The air glides upwards until it cools and the humidity condenses out falling as light rain.