The Alabama Climate Report

Brought to you by the Office of the Alabama
Climatologist

Volume 8, Number 9, November 2017

Has 2017 felt unusually warm to you?

Whether we noticed or not, for the year to date, 2017 has been one of the warmest years in the modern climate record. According to our friends at the Southeastern Regional Climate Center, the first 11 months of the year were the warmest on record for both Mobile and Montgomery, and the second warmest for Birmingham and Huntsville.

While daily high temperatures contributed to that, they aren't driving the warmer than normal average temperatures. While daytime highs have averaged warmer than normal, the nightly low temperatures are largely responsible for the high average temps. The average low temperature in Montgomery for the first eleven months of the year was about 3.5° F warmer than normal, while lows were 2.3° warmer than normal for Mobile. Those are the warmest lows on record for both cities. Huntsville's +2.2° and Birmingham's +2.6° were only the second warmest.

Alabama has gotten some rain this year, especially in the southern two-thirds of the state. Mobile, Montgomery and Birmingham all saw their third wettest January through November. On average, the three cities are almost 18" ahead of normal for rain in 2017. If they don't see a drop of rain in December (which is rare, but does happen), they would still finish the year wetter than normal.

Huntsville, by comparison, is only 0.8" wetter than normal for 2017.

The rain might help explain some of the warmer than normal lows. Clouds and humidity at night tend to trap heat near the surface, raising nighttime temperatures.

Looking back through the year, we note June was especially ... damp, with an average statewide rainfall of 10.56". That included 19.96" in Greensboro and 18.1" in Thomasville.

November, by comparison, was warmer and drier than normal. More than a third of the stations in our monthly sample saw their driest November on record. That includes Birmingham (1.44"), Huntsville (0.89") and Mobile (0.48"). Other records were set in Brewton (0.76"), Fairhope (0.20"), Gadsden (1.04"), Muscle Shoals (1.41") and Scottsboro (1.07").

In that list, Mobile and Scottsboro are noteworthy for the length of their climate records. Climate records from Scottsboro go back to 1891, while Mobile's begin in 1893.

We are beginning to see a pattern consistent with a La Niña Pacific Ocean cooling event. When the temperature of sea surface water in the eastern Pacific along the equator drops, it shifts weather patterns around the globe. Weather is typically a bit warmer and drier along the gulf coast and a bit wetter in the Ohio valley, which is what happened in November.

We should also note that the warmer than normal November pushed back the arrival of the first "killer" frost of the winter by a few days. A cold front on Nov. 20 brought 28° or colder temperatures to most of north Alabama, as far south as Montgomery and Tuscaloosa. That was a week and a half later than normal for northern stations, but only two days late in Montgomery.

 

- John Christy
The Alabama State Climatologist