Slight chance of unusual weather Saturday

Published 7:00 am Saturday, February 1, 2020

By Skip Rigney

Saturday is forecast to be cool and cloudy, not unusual for February. Although the day should be mostly dry, the National Weather Service in Slidell noted in its forecast discussion a very slight chance for some uncommon weather.
A trough of low pressure in the middle and upper atmosphere will be moving from Texas through Mississippi on Saturday. The air several miles above us in the low pressure trough will be very cold and dry compared to the air at the surface. Midday Saturday, the temperature here at the surface is forecast to be in the upper 50s with about fifty percent relative humidity. Meanwhile, the temperature 18,000 feet above us is predicted to be five below zero with a relative humidity of ten percent.
If the sun manages to pop out Saturday around midday, it could heat up the surface enough to get a few pockets of relatively moist surface air rising. If those blobs of moist air become buoyant enough to rise several miles into the cold, dry air above, puffy clouds containing some small hail could form.
We’re talking pea-sized or smaller hail. Nothing severe or damaging, but something that would get your attention if you happen to be outside.
While possible, the NWS described the chances of small hail forming as “highly unlikely.” The more likely scenario is that there will be too many clouds Saturday morning and midday to allow the sun to heat the surface enough to get those parcels of moist surface air bubbling upward.
By Saturday afternoon, drier air will be moving in at the surface, and skies will gradually clear. Sunday should be sunny, starting in the upper 30s, then warming to the upper 60s.
By Monday winds are forecast to shift back to the south. The flow off the Gulf will send high temperatures Monday, Tuesday, and Wednesday into the lower 70s ahead of a midweek cool front. That’s about ten degrees above average for early February, but well below the toasty records set back in 1957 when the temperature at Poplarville reached 82 degrees on February 3rd and 84 on February 4th.
While we won’t set any records, the upcoming mild spell will be a reminder that we can expect more spring-like days to sprout up now that it’s February. Our average winter temperature for Pearl River County reaches its nadir in mid-January, when the average low is in the upper 30s and the average high is around 60. The exact values vary slightly depending on your location within the county, and also the number of years used to calculate the averages.
In late January and early February, the averages begin a slow climb. By mid-February, the increase in the averages accelerates. By the end of February, the average lows in Pearl River County are 43-45 degrees, and the average highs are 66-68 degrees.
But, as I often point out, averages are just the middle part of what can be a large range. During the first two weeks of February 1899, large chunks of ice floated down the Mississippi River past New Orleans where it was six degrees. Mobile, Alabama, dropped to one below zero.
Compare that to two years ago when high temperatures were in the 80s for nearly the entire last week of February 2018.
Anything can happen in February.

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