Year-to-Date Rainfall Update

Many Alabama communities have done some “catching up” on rain over the past two weeks thanks to widely scattered yet very heavy thunderstorms. Some spots have been pounded over and over with torrential rain while others have had a sprinkle here and there. Scattered storms do not give us a good, even coverage of rain, so while one area like the Birmingham-Shuttlesworth Airport is closing the gap on 2011’s rainfall deficit, other places like Montgomery, Anniston and Tuscaloosa are still way behind on the year.

City………Deficit/Surplus
Birmingham……………..-0.86″
Tuscaloosa……………..-8.34″
Anniston……………….-5.84″
Huntsville……………..+1.57″
Montgomery……………..-6.75″

Tuscaloosa got 1.22″ of rain in a heavy storm on Sunday and it is still 8.34″ below average. That is a significant deficit that these scattered storms will not likely wipe out. Numbers are one thing, but a picture is worth a thousand words (or numbers). Here’s a map from The Advanced Hydrologic Prediction Center that shows just how far below or above normal the entire state is based on doppler radar estimates:

AHPS Estimated Rainfall Departure from Normal (Jan 1 to Present)

The colors match up pretty well with the actual “official” airport observations, so it is not a stretch to say that some areas are as much as 10 to 15″ below average right next to communities that are near or a little above average!

It will take several widespread soaking rain events to ease the drought over South Alabama. In the Central and Northern parts of the state, recent rain may not have erased the deficits, but it has eased “drought” conditions in a lot of places. The difference in a deficit and a drought is simple. Droughts are prolonged dry spells that affect water supplies to people and/or agriculture. A deficit is simply a statistic showing rainfall relative to a normal value. You can have a deficit without a drought because droughts are visible results of a lack of rainfall.

-Jason
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