Climate

According to the National Severe Storms Forecast Center, tornado frequency is maximum in central Oklahoma and drops off toward the south and east before rising again in central Florida.  Alabama averages about 22 tornadoes per year.  For this reason, tornado property damage in Alabama ranks behind the “tornado alley” states as well as such states as Georgia, Minnesota, Missouri, Indiana, Ohio, Illinois, Iowa, Pennsylvania and Massachusetts.   The likelihood of a tornado setting down on a specific acre in a given year in Alabama is about 1 in 13,000. In other words, there is a 50% chance of being in the path of any tornado (most are weak) about once in 600 years.  The standard reference for tornadoes is the annual occurrence within 10,000 square miles.  For this region in Alabama, the number is 4.5 for all tornadoes, and 2.0 for category F2 or greater.

The straight-line distance from the Gulf Coast to Etowah County is approximately 250 miles.  Hurricanes lose energy as soon as landfall is made, so we have not recorded hurricane-force winds from a tropical system in this area.  The main threat in the inland areas is flash flooding due to heavy rain, although events such as this are extremely rare because our runoff systems already accommodate heavy rain events.

Alabama’s abundant rainfall assures that generous sources of fresh water are readily available.  With plentiful rainfall being the norm, damage due to extreme rainfall events is rare because the runoff systems (natural and manmade) have evolved to handle large amounts of water.  The Coosa River is dammed and is managed to minimize flooding impacts.   From rainfall frequency calculations, local rainfall can reach 7.5 inches in 24 hours once per century.

Hail is relatively rare in Alabama, occurring on average only 1 to 2 days per year.  Hail events occur with greater frequency and with generally larger stones in every state northward to Canada and westward to the Pacific coast because hail-producing thunderstorms require especially cold and dry air at the upper levels, a condition fairly rare in the Southeast.  The average number of events ranges from 2.2 days per year in North Alabama to 1.3 days per year along the Gulf Coast. The great majority of these events cause very little damage because stones are only pea to marble in size.

Etowah County is categorized in range IV of the Modified Mercalli Intensity Scale (some shaking, no damage.)  Such events are extremely rare.