Late summer weather continues in Ida’s wake

Published 1:28 pm Sunday, September 5, 2021

By Skip Rigney

Hurricane Ida dealt Pearl River County a glancing blow as the storm’s inner core passed well to our west across Louisiana.

The two official NOAA wind measuring stations closest to Pearl River County that made observations during Ida’s passage were the National Ocean Service’s anemometer on the shoreline of Bay St. Louis and the National Weather Service’s automated surface observing station at the Slidell airport.

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The “sustained wind” is the average of all wind speeds observed over a two-minute period. The highest sustained wind measured at Bay St. Louis was 54 mph at about 8PM Sunday. Sustained winds there were between 30 and 45 mph almost continuously for 24 hours from Sunday morning to Monday morning. Two peak gusts of 67 mph were among the many gusts above 60 mph coming off the waters of Bay St. Louis Sunday evening into early Monday morning.

The Slidell airport, although a little closer to Ida’s maximum winds, is more inland than the Bay-Waveland station, and so is probably more representative of what was experienced in Pearl River County, especially the southern part of the county.

Slidell’s sustained winds were between 25 and 40 mph between 6:00 PM and 11:30 PM Sunday, the latter being the last report from the station until Monday afternoon. The peak gust recorded at Slidell was 63 mph at 7:53 PM.

Based on these stations, along with what I observed at my home several miles east of Picayune, I estimate that sustained winds across the county were generally in the 25 to 40 mph range with numerous gusts into the 50s and 60s.

Some higher gusts almost certainly occurred in several short-lived tornadoes, some of which were detected by the NWS radar in Slidell, as they raced across the county.

Rainfall estimates from that same radar varied widely across Pearl River County. The highest rainfall appears to have occurred, interestingly enough, farther from Ida’s center track, east of I-59 where 7 to 12 inches were common. The lowest accumulations were in the northwest part of the county where 4 to 5 inches were more prevalent.

Ida is gone, but hurricane season is not. In fact, we’ve just started the busiest month for the Atlantic basin, including the northern Gulf Coast. Here are the number of tropical storms and hurricanes by month whose centers have passed within 80 miles of Picayune (roughly between Baton Rouge and Mobile) since 1850: May-1, June-10, July-8, August-21, September-40, October-13, November-2.

Some slightly drier air began drifting into the atmosphere above south Mississippi on Friday. That means only isolated showers, if any, today and Sunday.

However, by Labor Day moisture is forecast to return through a deep layer of the lower and middle atmosphere, and with it scattered to numerous daytime showers and thunderstorms.

The jet stream is forecast to push a cool front into central Mississippi by mid-week. The front could get tantalizingly close to us by Thursday or Friday.

As long as we are south of the front, late summer weather will continue. And, as we watch the front to our north, the computer models hint that we might also be watching a weak disturbance in the Gulf by the middle to latter part of the upcoming week.