Fall finally arrives, another cool front on the way

Published 7:00 am Saturday, October 13, 2018

By Skip Rigney

Early Thursday morning autumn finally made it to Pearl River County. There was no doubt when you stepped outside that the old summer air had been replaced by cooler and, most noticeably, lower humidity air.

You probably missed the first hint that a change was on the way. That hint came with a weak front that moved across our area on Wednesday afternoon. Winds were already blowing gently from the northwest, but once the front passed drier air began to move into the region. Dewpoint temperatures, a good measure of the amount of moisture in the air, fell slowly Wednesday afternoon and evening from the muggy lower 70s into the not-so-sticky middle 60s.

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But the change that you could really feel came with a second, stronger cool front that entered the northwest corner of the county around 1:00 A.M. Thursday and exited the southeast corner of the county less than two hours later. Temperatures across the county dropped into the middle 60s by sunrise Thursday.

Even with sunny skies during the day on Thursday and Friday, the cooler air mass only warmed into the lower 80s. Early May was the last time that we had such mild temperatures.

The National Weather Service office in Slidell noted in their forecast discussion on Thursday morning that, “A subjective analysis shows this recent cold front may be the latest ever first cold front of the fall season,” for south Mississippi and southeast Louisiana.

Not only can we thank the front for finally bringing us cooler, less humid weather, the surface front and the associated trough of low pressure in the upper atmosphere helped keep Hurricane Michael far to our east.

That was bad news for the folks in the Florida Panhandle from Panama City eastward. Hurricane Michael slammed into that region with some of the highest winds ever to hit the United States mainland at 155 mph. Only the Florida Keys Labor Day hurricane of 1935, Camille on the Mississippi Gulf Coast in 1969, and Andrew in Miami in 1992 had higher winds at landfall.

Without meaning to minimize the destruction and distress wrought by Michael, I will mention a trivial benefit of the path and the strength of the hurricane. As Michael raced off to the northeast, it’s counterclockwise circulation, which is the same direction in all low pressure systems in the Northern Hemisphere, reinforced the northerly winds over the Gulf South on Thursday bringing dry, cool air even further south than would have happened otherwise.

Sunday you may wonder whether fall was just teasing. The wind will switch back around to southeasterly, which means a return of moist, warm air from the Gulf of Mexico. Sunday’s high temperature is forecast to be in the upper 80s, and you will definitely feel an increase in humidity.

However, another cool front will be riding to the rescue as it plows southeastward out of the Great Plains on Sunday and into the Gulf South on Monday. Instability with the front will bring a chance of showers and thunderstorms. Once the cool front passes through on Monday or Tuesday, expect a return to normal October temperatures.

Maybe hot weather is over for the next six months or so.