Squall line headed this way
Published 7:00 am Tuesday, November 17, 2015
In last week’s column I discussed the fact that more severe weather occurs in November and December in the Gulf South than at any other time of year except spring.
The ingredients appear to be coming together to give us a chance of seeing some of that severe weather as early as this afternoon, tonight, and into the morning hours Wednesday.
Forecasters expect a squall line of rain, gusty winds, and thunderstorms to move through our area ahead of a cold front. Some of the storms could be severe, and there’s even a slight chance that they could produce tornadoes.
As I am writing this on Monday morning, it is still too early to nail down the exact timeframe for the squall line.
Stay connected to your favorite weather app, television or radio weather information, or keep a weather radio nearby this afternoon through early Wednesday morning.
Fortunately, the squall line will be moving relatively quickly, so the heaviest weather should only last an hour or two. However, even during the day today and overnight, some isolated thunderstorms could develop in the warm, soupy air well ahead of the squall line. Because wind speeds will be high at upper levels in the atmosphere, and the wind direction will change significantly from the surface to those higher altitudes, some of those isolated thunderstorms could begin to rotate and become so-called supercells capable of producing tornadoes.
The National Weather Service (NWS) Storm Prediction Center, located in Norman, Oklahoma, is responsible for predicting the threat of severe thunderstorms and tornadoes and issuing watches for areas with heightened risk.
Their job is similar to what the NWS’s Hurricane Center in Miami, Florida, does for tropical weather.
Keep in mind that even though our chances of a severe thunderstorm or tornado over the next 24 hours will be higher than during a typical cold frontal passage, those chances are still less than 50%. In the Storm Prediction Center’s outlook issued Monday morning, Pearl River County is right on the line between the areas for “slight” and “enhanced” risk of severe thunderstorms Tuesday afternoon, evening, or early Wednesday morning.
This corresponds to a 15 to 30 percent chance that a severe thunderstorm will happen within 25 miles of us.
There will be a lot of moisture associated with this weather system. Rainfall amounts ranging from one to three inches are expected in our area.
Even after the squall line passes, some showers are forecast to linger Wednesday.
Once those showers end sometime during the day on Wednesday, behind the cold front, Tuesday’s warm, soupy air will be replaced by drier, cool air blowing in on a northerly breeze as high pressure builds into the Gulf states.
After flirting with 80 degrees this afternoon, high temperatures are forecast to be in the 60s or at most lower 70s for the rest of the week, which is very typical for mid-November. Beginning Thursday morning and through the weekend, lows will be in the upper 40s to near 50 degrees, which is just slightly above normal.
By Skip Rigney