The Alabama Climate Report

Brought to you by the Office of the Alabama
Climatologist

Volume 9, Number 3 June 2018

People often ask me what the weather will be over the summer.  Usually the key interest is whether it will be wet or dry.  As far as I know, I’ve never made such a forecast for the summer months.  The rainfall pattern from this past June will tell you why.  Now, most of you know that when summer comes, the spotty, scattered, chaotic, hit-and-miss, and unpredictable thundershowers arrive as well.

The plot below shows how much rain fell in Alabama as a percentage of normal in June.  About half of Alabama was above normal and half below normal.  Some spots in Tuscaloosa and Hale counties received less than 25 percent of normal, while in places in adjacent counties of Walker and Marengo, rainfall totals were over 200 percent of normal.  In Butler Co., we saw over three times the average.  So, who could have forecasted something so variable?  Not me.

If in May you had predicted Alabama would have normal rainfall for June, you would have been right for the state average, but wrong in nearly every particular spot.  And, people live in specific spots, not all over the state at once. This is why I don’t forecast summer rainfall totals (and be wary of anyone who does).


(see full image)

Percentage of normal rainfall in June 2018 from NOAA.

Speaking of rain, have you ever heard of a Derecho?  This is a complex of intense thunderstorms that is especially long-lived and is usually accompanied by high winds.  Alabama experiences about one of these every two years. On June 28th one of these damaging complexes moved over 400 miles from Kentucky to the Gulf, crossing Alabama as its leading edge fed off the extremely warm and humid air, leaving downed trees and power lines in its wake.  The NWS office in Huntsville has a nice explanation and video of the event here.

https://www.weather.gov/hun/event06282018

Temperature-wise, June was a bit above average, around 2.5 °F statewide.  Tuscaloosa, in that dry spot, came in at 3.9 °F above average while Anniston, in a wet spot, was only +1.7 °F above average.

July is now here and represents the month in which the bulk of the state, roughly the southeastern two thirds, generally experiences its hottest day of the year.  For the northwestern third however, that normally comes in August with the far northwest seeing their hottest day in the second half of August.  This late heat in the north is related to common short periods of drought that tend to occur later in the summer as the distance from the warm, moist Gulf air increases.

- John Christy
The Alabama State Climatologist