Cooler air headed this way

Published 7:00 am Tuesday, April 4, 2017

By Skip Rigney

Early Monday morning many of us awoke to cracks of thunder and wind-driven rain pelting our windows.

For the next hour heavy rain fell, lightning flashed, and thunder rumbled almost continuously. The rain continued for about three hours with two to three inches falling across much of the county.

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The squall line responsible for all the noise was typical of these weather makers that often move through the Gulf South in springtime.

Strong low pressure to our northwest in Oklahoma was moving slowly northeast. Southeast of the low pressure center was a warm, moist, and unstable sector of air, which was the perfect breeding ground for strong thunderstorms. The thunderstorms merged together into a solid line and moved eastward out of Louisiana.

Often a squall line will run out ahead of the cool front that extends southward from the center of the low. That was the case Monday. The squall line had passed us by 8:30 a.m. and was headed into Alabama and Florida.

Meanwhile, the weak cool front associated with the low-pressure system was still several hours behind the squall line back in Louisiana.

By Monday afternoon the weak cool front passed us and moved into the northern Gulf of Mexico.

But, that front quickly came to a halt, reversed directions, and early this morning headed back northward as a warm front as it was attracted by the next disturbance in the atmosphere moving into the Great Plains.

That disturbance shows up in several ways on the weather maps. If you look at today’s weather map for an altitude of approximately 30,000 feet above sea level, you will see a southward dip or trough in the wind pattern over the Great Plains from Canada all the way down to New Mexico.

The same disturbance shows up on the surface weather map as a counterclockwise spiral of winds around low pressure in the panhandle of north Texas.

By Wednesday night that surface low is forecast to have moved northeastward one thousand miles from Texas to Indiana. Trailing southward out of the center of the low all the way from Indiana down into the Gulf of Mexico will be the strongest cool front that we have seen in three weeks.

Low temperatures Wednesday night will be near 50 degrees, and on Thursday night and Friday night will drop into the 40s according to National Weather Service forecasters. March 14, 15, and 16 were the last nights that were that cold.

The cool front may kick off showers and thunderstorms Tuesday night or Wednesday as it approaches from the northwest. But, behind the front on Wednesday night through Sunday, expect high-pressure to give us fair skies.

The April sun will warm us up nicely after the cool mornings on those days, but the air mass is forecast to be cool enough that temperatures are forecast to rise only into the 70s.

Sunday’s high may creep back to the lower 80s.

So, enjoy the beautiful mild, even cool, spring weather later this week. As April wears on we will be seeing more days with highs in the 80s.

It’s possible that we could see our first 90 degree day of the year. That has happened in April in ten to twenty percent of the years since weather record keeping began in our area.