One Number Town? Hardly!

Last night was a prime example showing that (on certain nights) using a single number to forecast the low is a hazard to a weather person’s sanity.

We used 30 as the expected low for Birmingham. That turned out to be exactly right based on the official observations at Birmingham Airport. But look at these great variations around Central and North Alabama:

* a 14-degree difference here in Jefferson County from a low of 24 in Pinson to 38 Downtown Birmingham. It is true that the 38 comes from the Skycam atop the Daniel Building. However, that is probably typical of lows atop Red Mountain, Shades Mountain and Double Oak Mountain. (where humans live)

* 33 atop Mt. Cheaha (highest point in Alabama) was seven degrees warmer than the 26 at Anniston Airport.

No fronts involved.

Blame it on temperature inversions.

On clear nights, the air adjacent to the ground cools and being heavier, sinks or slides into the valleys and lower elevations. With a high pressure area trying to get out of town and moving east, the wind picks up first on the ridges and mixes the air.

Some more lows across Alabama last night. Note the colder lows in the East and NE locations.

17 Broomtown
18 Muscadine
19 Sycamore
21 Scrougeout*
22 Decatur
24 Coker, Concord/Hueytown
25 Tuscaloosa, Weaver
26 Huntsville
27 Cullman Airport, Noccalula Falls

* At one time this morning the temperature at Scrougeout (NE Etowah County) rose rather quickly from 21 to 30 and then dropped back to 25. No clouds, just a slight pickup in the wind mixing the air not far off the ground with the colder air at ground level.

Tricky business sometimes trying to forecast the weather! Some weather people don’t have much hair left!

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