The Alabama Climate Report

Brought to you by the Office of the Alabama
Climatologist

Volume 8, Number 1 - October 2017

In addition to keeping an eye on Alabama's weather and climate, at UAH we also spend a fair amount of time using instruments on NOAA and NASA satellites to track temperatures in almost all of Earth's atmosphere. We build datasets of those temperatures and how they have changed through time since late November 1978.

Sometimes those two things merge or overlap, as they did this month.

On the local front, NOAA is predicting that Alabama should see a warmer and drier winter than normal this year into next, based in part on a predicted La Niña Pacific Ocean cooling event developing this winter into the spring.

At the same time, the Southeastern Regional Climate Center says that at least for Alabama's four largest cities, the first 10 months of 2017 put the year on pace to be the warmest year in the SERCC climate record, at least based on average temperatures.

When we look at the global temperature during the past several months, however, another issue pops up: an unexpected warming in the eastern equatorial Pacific in June and July.
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It wasn't an El Niño warming event. We've all gotten much more familiar with the effects those Pacific Ocean warming events have on regional climates around the world. This warming was at the wrong time of year and it didn't last very long. Then, things got really turned around.

That doesn't mean it isn't having an effect on the climate, or that it won't have an effect on Alabama's climate. Instead, we can probably expect that surge of warm air to slightly boost temperatures in Alabama for the next several months. It works like this: What goes up, keeps going up!

When we see high values in sea surface temperatures like those this past summer, they eventually fall back down. This time they dropped rapidly. But the heat the leaves the ocean must go somewhere. A lot of it ends up in the atmosphere before it is expelled into space.

It takes a month or two for that heat to rise out of the ocean and warm the air above it. Once that happens, part of that extra punch of warm air starts to spread both north and south from the Equator. This takes several months. In fact, our data suggests the peak warming from last summer's warm Pacific will hit the latitudes that include the U.S. contiguous 48 states (including Alabama) in about ten months after the peak warming in the Pacific.

That means there should be some extra heat trickling in from the south throughout the winter and early spring, with that Pacific heat peaking around these parts from March through May.

During a La Niña event, winter in Alabama tends to be warmer and drier than average. But that's an average. As our friends at the National Weather Service were at pains to remind us, that doesn't mean we won't see cold snaps or "winter weather events." In fact, some of us might recall that a steady flow of warm, moist air from the gulf has been the lead up to several significant "winter weather events" in recent history. It wasn't that long ago (2015) when several stations in north Alabama received their record total of February snow.

All it takes is a moist atmosphere and a single cold front, and we can see a run of eggs, bread and milk.

This being Alabama, we would be remiss if we didn't remind everyone that in our state, tornado season never really ends — and that there is  a secondary peak in the late fall. This month is the 60th anniversary of November 1957, when the state was hit by 17 tornadoes (and this back in the day before Doppler radar and such). That includes an outbreak on Nov. 17 and 18, when 15 tornadoes — including an F-4 in Walker County and an F-4 in Blount County — caused eight fatalities and 71 injuries.

Let's be weather aware and weather prepared.

 

- John Christy