A few days break from high humidity

Published 7:00 am Tuesday, September 20, 2016

Sunny days with only the slightest chance of showers are forecast through Thursday before higher humidity and a few more showers return for Friday through the weekend.

A few dry days will be a welcome change from last week’s damp weather. Most of the county saw rain on at least six of the seven days from last Monday through this past Sunday. Total accumulations in the southern part of the county ranged from two to over three inches.

The heaviest showers occurred Friday and Saturday and impacted much of coastal Mississippi, something that those who attended Picayune High School’s football game at Harrison Central got to observe first hand.

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Weak low pressure over the northwestern Gulf was the main feature responsible for the wet weather.

The circulation around the low pumped plenty of moisture into our area and enhanced lift in the atmosphere.

A weak frontal boundary sagged southward yesterday. The boundary is predicted to stall just south of us and dissipate. However, winds behind the front in the lowest two miles of the atmosphere are northerly, and are bringing much drier air from our north into south Mississippi.

Precipitable water is a measure of water depth if all the moisture in the column of air above a location were to condense and fall as rain.

Precipitable water values are forecast to be around one inch today and tomorrow, which is less than half what they were over this past weekend. Dew point temperatures, a good indicator of how muggy the air feels, will drop into the middle 60s today and tomorrow. Most of the summer they have been in the 70s.

Not only will the dry air over the next few days mean that our rain chances decrease to only about ten percent, the drier atmosphere will allow more of the day’s heat to radiate away from the surface overnight.

Low temperatures early on Wednesday and Thursday could drop below 70.

We will still have hot afternoons, however, with highs reaching into the lower to middle 90s.

By Friday, our brief respite from the humidity will end. The forecast for Friday through Sunday is typical late summer, warm and muggy with a chance of showers.

This Thursday is the September equinox, also known as the “first day of fall” in the northern hemisphere.

For those in the southern hemisphere, it is their “first day of spring.”

This is only one of two days each year, the other being the March equinox, when the sun’s rays are hitting the Earth at the same angle at locations which are the same distance north or south of the equator.

Two other things make the two equinox days special. The sun rises and sets almost directly due east and due west, no matter where you are on Earth. Also, the day and night are each approximately 12 hours long.

However, don’t expect our weather to immediately turn fall-like just because Thursday is the autumn equinox.

We will need to wait at least until next week. Over the past several days, the computer weather models have been flip flopping as to whether next week will bring our first strong cool front of fall.

By Skip Rigney