Parade of fronts a contrast with December

Published 12:02 pm Saturday, January 8, 2022

By Skip Rigney

During most of December we were locked into a stagnant weather pattern. Warm air covered the southeastern United States, and the cool fronts that did make it into our region were weak.

Now in January we are in a much more changeable pattern as cool fronts are sweeping down out of the Great Plains every few days. A front passed through early Thursday evening. The cold air behind it dropped temperatures from 70s on Thursday afternoon to lows of 30s on Friday morning and highs in the 50s Friday afternoon. This weekend we will see a return of mild air before the next front sends our roller coaster ride of temperatures downward Sunday night.

The surface weather maps shown here are from the National Weather Service’s Weather Prediction Center. I’ve added a few words along with arrows showing wind direction. Pearl River County is represented by the star on the map.

Sunday we will be in mild southerly winds as air rotates around a high pressure system centered off the east coast. The most numerous lines on the map are called isobars, which are lines of equal pressure. Sunday we will find ourselves between the lines representing 1024 and 1020 millibars of sea level air pressure.

As winds bring in mild, moist air from the Gulf, low pressure developing along the front in Oklahoma will provide the instability needed to spark showers and thunderstorms ahead of the front across our region on Sunday.

Winds generally blow along the isobars with a slight component away from high pressure and toward lower pressure. The closer the isobars are together, the stronger the winds. That’s why on Monday, with the cold front to our east and the isobars packed closely together over the Gulf South, expect a breezy day with north to northeast winds bringing in cold, dry air.

After a warm-up beginning Wednesday and continuing through the end of the upcoming week, expect another cold front to pass through, once again dropping our temperatures sometime next weekend.