Sunday, October 18, 2009

Freeze Warnings in October?

Freeze Warnings have been issued from the National Weather Service Office in Jackson for Jasper and Clarke counties. (Other counties not in our viewing area include WEBSTER-CLAY-LOWNDES-CHOCTAW-OKTIBBEHA-WINSTON-NOXUBEE-NESHOBA-

This freeze warning is due a stable air mass (high pressure) placing directly over central Mississippi going into the night. The contribution of the high pressure system is cold and dry air along with calm winds. All of these points will help drop temps across the area into the 30's. Some spots to the northeast of Hattiesburg will be in the main corridor of "coldest temps".

My opinion: I'm still a little concerned about the freeze warnings issued b/c of several factors. One factor is the warm soil temps. Even though a cold air mass is above the surface, it doesn't mean the soil is cold as well. Just a week ago, soil temps were still near 80 degrees. Also, I know radiation cooling will take place to remove plenty of energy from the surface, but dewpoint temps will hover near 33/34 degrees for a couple hours overnight. I believe most folks in our viewing area will stay between 35-37 tonight.

Also, some folks could see patchy frost develop before sunrise. Overall, this will be the coldest night of the season, but the next 3 days will steadily warm into the upper 70's again.

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