The Alabama Climate Report

Brought to you by the Office of the Alabama
Climatologist

Volume 6, Number 10, July 2016

You might recall (I had to look it up) that back in May we talked just a bit about the impact a developing La Niña Pacific Ocean cooling event might have on summer weather in Alabama, as well as on the Atlantic hurricane season.

It has been just a couple of months since then, but things haven't gone exactly as expected — although the state's weather has been doing pretty much what we forecast.

We said in early May that if the eastern Pacific Ocean along the Equator near South America shifted this summer from a warm phase to a cool phase, during that transition period we would have a better than normal chance for a summer that is warmer and drier than usual, especially in the southern two-thirds of the state.

Through June and July it has been that, somewhat. In most places. Except where it was cooler and/or wetter. (Jasper saw three one-day rainfall records broken in July, including its wettest July day on record, 4.93" on July 10.)

That's the thing about summer weather in Alabama. It can be spotty. A thunderstorm can pop up and drop a couple of inches of rain on one side of the road while leaving the other side completely parched. Check out the climate summaries for the place-by-place data. In our 24-site state survey (Gainesville Lock was off-line for a large part of July), 17 were warmer than normal in July, while 14 were drier than normal. That leaves large swaths of cooler and/or wetter.

But the La Niña transition doesn't seem to be much at work on our weather this summer because that cool pool isn't developing as rapidly as expected. Sea surface temperatures in that part of the Pacific are cooler than normal, but the NOAA forecast for the region says there is only a 55 to 60 percent chance an actual La Niña event will happen this fall.

That isn't necessarily a bad thing. Atlantic hurricanes tend to be more common during La Niña years, and it has been a relatively quiet hurricane season. Part of that, however, might have to do with a large region of cooler than normal water puddling about in the northeastern Atlantic.

While a cool eastern Pacific tends to enhance the formation of hurricanes, a cool pool in the North Atlantic tends to block them. So far this summer it seems the cool Atlantic is winning the meteorological tug of war.

This doesn't mean, however, that we get a free pass on being weather prepared. It takes only one bad tropical system to cause havoc and destruction. Think hurricane Andrew. Andrew was the only major Atlantic hurricane in 1992, but it was more than enough.

This October 24 will be the 11th anniversary of Wilma coming ashore in Florida as a category 3 hurricane — the last "major" hurricane to hit the continental U.S.

We are overdue, so let's also be prepared.

- John Christy