Volume 3, Number 12, September 2012
One of the things we climatologists love about our work is that something interesting is almost always happening somewhere and usually not too far away.
Take September, for example. Looked at in the aggregate, September wasn't very ... unique. I know that after a summer of drought followed by the hurricane Isaac double whammy, a lot of people were happy for the weather to get back to "normal."
In our statewide sample (not the official NWS survey) the average temperature was a couple of degrees cooler than normal for September, and we averaged about 1.1 inches of rain more than is normal for the month. On average.
But averages don't always tell the story, and they frequently smooth over some of the most interesting events. If you look only at the average statewide precipitation, you might not notice that both Centreville and Childersburg had their wettest September days "ever" last month. On Sept. 17 Centreville got 5.6 inches of rain, more than many places in Alabama got for the entire month. Childersburg topped that on Sept. 29 with 7.9 inches of rain in one day.
(We put those quotes around "ever" because the Childersburg station's official record goes back only 55 years, and Centerville's only 37. In those cases "ever" is a relatively short period of time.)
Average wouldn't notice that there were at least 26 reports of flash flooding in the state during September; two bridges in Gordo were reported to have been "washed out" by flooding.
The damp statewide average rainfall also wouldn't tell you that some places in east Alabama saw less than half of their normal rainfall for the month. Not raining might qualify as a weather non-event, but that doesn't mean it isn't interesting and important.
Some areas that saw less than normal rain for the month are still under serious drought conditions, although the situation in Alabama is steadily improving. Three months ago more than 90 percent of the state was in some stage of drought, with almost one-third under severe to exceptional drought.
Now, just under a fourth of the state remains in a drought. Less than seven percent of Alabama remains under the most serious and damaging drought conditions. Like I said, that's one of the things that makes climatology interesting. No matter how "normal" a month might look from a statewide perspective, somewhere at some time someone will have an unusual weather event in an area the size of Alabama.
And always watch out for "average."
- John Christy