On track for possible rainfall record
By Skip Rigney
Wet is the word throughout Pearl River County. Historically, our average rainfall for the entire month of April is about five inches. Some locations, especially in the southern half of the county, received that much in less than twelve hours last Friday night and early Saturday morning, April 9-10, and then again this past Wednesday through early Thursday morning, April 14-15.
Based on data available on Friday morning, rainfall totals for the first half of April ranged from 8 to 13 inches in the southern half of the county and 5 to 8 inches in the northern half of the county. Those accumulations are based on a combination of local rain gauges and estimates from the National Weather Service radar in Slidell.
The soggy start to the month has affected a broad swath of the Gulf Coast from Lafayette, Louisiana, all the way to Panama City, Florida. Maps of the observed precipitation are available online from the NWS’s Advanced Hydrologic Prediction Service at https://water.weather.gov/precip/
As I write this on Friday morning, it is raining again. NWS forecasters say another couple of inches of rain is likely to fall before ending sometime Saturday night. At this rate, April 2021 is in the running to be one of the wettest Aprils on record in the southern half of the county.
All of that rainwater has to go somewhere, and area branches, creeks, rivers and even lakes are very high. The NWS in Slidell expects moderate flood levels to continue on the West Hobolochitto through the weekend, with the East Hobolochitto at lower, but still elevated, levels. The Pearl River is forecast to continue at moderate flood stage for at least another week.
NWS stream predictions are available online at https://water.weather.gov/ahps/ under the “River Forecast” tab.
The culprit for our heavy rain has been a surface front stuck over the Gulf States or just offshore for over a week now.
In the atmosphere miles above us, the subtropical jet stream has blown in an ample supply of moisture from over the Pacific Ocean.
At the same time, a seemingly unending series of disturbances in the high-altitude winds have interacted with the front to provide the lift needed to produce our rain clouds.
Tonight the cold front is expected to sink further south into the Gulf than it has all week. This will allow some drier air to work into the area from the north, significantly lowering our rain chances Sunday and Monday.
What we need is a strong southward dip in the polar jet stream to push some cooler, drier air out of Canada and finally sweep the cold front and the high humidity to our south and east for good.
That is expected to happen Tuesday. By mid-week skies should finally clear and northwest winds will help dry us out for a few days.
But don’t expect the sudden onset of a drought.
By Friday or Saturday, the next low pressure system will be headed our way out of Texas and we will be in for another round of springtime showers and thunderstorms.