Houston, New Orleans facing dangerous severe weather threat Tuesday
An outbreak of severe weather, including the dangers of flooding rainfall and tornadoes, is likely to erupt and extend into the nighttime hours, adding to the dangers.
An outbreak of severe weather, which could include tornadoes and damaging winds, is likely to erupt across the South Central states, AccuWeather forecasters say.
Severe thunderstorms will erupt across the southern United States, targeting areas from Texas to North Carolina Tuesday into Wednesday evening, AccuWeather forecasters warn. The thunderstorms will pose dangers including flooding rainfall, damaging wind gusts and isolated tornadoes, and the threats will continue into the nighttime hours.
“A new storm moving out of northern Mexico, which will gather moisture from the Gulf of Mexico into Tuesday night, will be the impetus for the severe weather risk that begins in the Lone Star State,” explained AccuWeather Senior Meteorologist Bill Deger.
The storm system emerged from the southern Rocky Mountains and pushed into Texas Monday night. The potent and strengthening storm was already responsible for more than 20,000 power outages in the Lone Star State prior to daybreak, according to PowerOutage.us. By the midday hours, the number of outages had swelled to 35,000.
Warm, moist air will be pulled from the Gulf of Mexico and clash with the cold mountain air on the northern flank of the storm. This, along with other ingredients, will align to spark strong to severe thunderstorms right into Wednesday evening across the Southern states.
The primary concern across central Texas into Tuesday evening will likely be substantial rainfall and powerful wind gusts. However, as the afternoon and evening progress, AccuWeather meteorologists say that locations farther east along the Gulf Coast of Texas, Louisiana, central and southern Mississippi and Alabama will face additional threats.
More than 36 million people were under a National Weather Service wind advisory, high wind watch or high wind warning on Tuesday in the Southern states.
“By late morning and afternoon, storms could start to turn severe in southeastern Texas, before spreading into the Lower Mississippi Valley on Tuesday night. Heavy, flooding rains are a big concern, but many storms will also be capable of producing damaging winds or a tornado,” stated Deger.
There is the potential for some damaging tornadoes to be concealed by heavy rain. A dangerous tornado or two cannot be ruled out ahead of a developing line of severe thunderstorms. That tornado threat will last past the daylight hours on Tuesday.
Cities with a high risk of severe weather that includes the potential for a strong tornado include Houston and Port Arthur, Texas, as well as Lake Charles, Louisiana, on Tuesday afternoon.
Cities facing a moderate risk for severe weather from Tuesday evening through Tuesday night include Baton Rouge and New Orleans, Louisiana, Mobile, Alabama, and Pensacola, Florida. Even motorists traveling along portions of Interstate 20 Tuesday night will need to monitor for storms in the area that can reduce visibility and cause transportation delays. Gusty winds accompanying thunderstorms can also down trees and power lines. In the strongest storms, damaging wind gusts can reach up to the AccuWeather Local StormMax™ of 80 mph.
In a more localized area, including Houston and Galveston, Texas, a combination of atmospheric factors has led to the need for a high risk, according to AccuWeather forecasters.
"The area in southeast Texas and far southwest Louisiana looks to see the best overlap between warm air from the Gulf of Mexico and very strong wind shear. This will allow for widespread thunderstorms to develop, many of them severe," AccuWeather Meteorologist Andrew Johnson-Levine explained.
Throughout the daytime on Tuesday, the feature of interest will stomp across central and southern Texas and spread general rainfall amounts ranging from 1-3 inches. Residents in Austin and San Antonio, Texas, could see rainfall amounts ranging closer to 0.75 of an inch to 1 inch, but cities farther southeast along the Gulf coast will be in the prime location to tap into the warm moisture and southerly flow and see higher rainfall totals as potent thunderstorms develop.
Tuesday evening and night can bring the most dangerous threats with conditions conducive for the development of damaging wind gusts, flooding downpours and isolated tornadoes. Forecasters are mostly concerned about areas south of the Interstate 10 corridor from southern Louisiana to far southern Alabama during the overnight period.
“A tornado risk at night is especially dangerous, so residents along the Gulf Coast will need to have a way to reliably get warnings while asleep,” warned Deger.
Into the morning hours on Wednesday, the threat of strong thunderstorms will shift eastward into Georgia and the northern panhandle of Florida. Thunderstorms will continue to push onward along the Southeast coast into Wednesday evening, bringing heavy rainfall and the risk for travel disruptions as far as North Carolina.
Forecasters point out that the atmosphere will not be as primed for severe thunderstorms on Wednesday but still will carry the threat of dangerous storms.
“By Wednesday, the severe weather threat will be somewhat diminished compared to Tuesday, as some of the storm’s best energy heads north toward the Ohio Valley. Regardless, thunderstorms are still expected over a large swath of the Southeast, with a continued risk for downpours, gusty winds and an isolated tornado,” said Deger.
Into the evening hours on Wednesday, the zone for heavy rain and storms will shift to the Carolina coastlines. Overall, from Tuesday to Wednesday, a widespread portion of the Southeastern U.S. will receive ample rainfall ranging between 1-3 inches for many. Some spots can receive localized amounts as high as the AccuWeather StormMax™ of 5 inches, which can flood roadways, elevate streams and rivers and cause reduced visibility and transportation delays.
By late week, the storm will track through the Northeast and New England states and continue to spread winter impacts along its northern flank.
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