(MENAFN- The Peninsula) The Washington Post
USA: A potent storm system - which unleashed at least 20 tornadoes and caused serious flash flooding from Texas to Pennsylvania - is finally pulling away.
The system spawned its first severe thunderstorms in Texas just after the total solar eclipse on Monday afternoon. It concluded with a spattering of flash flood and tornado warnings along the Eastern Seaboard Thursday night into Friday morning.
Population centers hit by damaging tornadoes included Katy and port Arthur in Texas; Lake Charles and Slidell in Louisiana; near Mobile, Ala; and St. Augustine, Fla.
Powerful winds along the system's path - topping 70 to 80 mph in some cases - cut power to several hundred thousand customers, with Louisiana being the hardest-hit state.
There were still nearly 20,000 customers in the dark there midday Friday and another 50,000 without electricity from Virginia to New York, which saw gusty storms Thursday night.
The system unloaded flooding rains in more than a dozen states, prompting the National Weather Service to declare four flash-flood emergencies, its most severe flood alert.
The emergencies were issued in East Texas, near the border with Louisiana; New Orleans; Tallahassee; and the west side of Pittsburgh.
High water submerged cars, poured into homes and businesses, flooded roads and forced multiple high-water rescues.
A brief period of quieter weather is expected through the weekend, but meteorologists are already monitoring the potential for an outbreak of severe storms in the Plains and Midwest early next week.
Tornadoes
On Monday afternoon, thunderstorms first erupted in Texas bringing baseball-size hail just north of Dallas.
Storms dropping hail the size of softballs continued on Tuesday before spawning a tornado in Katy, a suburb of Houston, early Wednesday morning.
It caused EF1 damage on the 0-to-5 Enhanced Fujita scale for intensity and heavily damaged a strip mall.
Storms merged into a violent line early Wednesday, spurring the Weather Service's Storm Prediction Center to draw a Level 4 out of 5 risk of severe weather along the Gulf Coast.
The squall line straddled a stationary front as it swept 650 miles eastward from East Texas to the Florida Panhandle, pushing damaging winds along its path.
Numerous tornadoes formed along the line.
Early Wednesday morning, Lake Charles was hit by an EF2 twister with 115 mph winds.
The tornado only lasted 4 minutes, but it damaged the east side of McNeese State University around 6:38 a.m. A half-hour earlier, the same storm complex dropped an EF2 tornado in Port Arthur, Tex.
Midmorning Wednesday, a damaging EF2 tornado hit areas near Slidell, La., causing numerous injuries.
By Thursday, the Gulf Coast batch of storms was beginning to weaken as the parent low pressure system lifted northeast over Ohio.
But the storm system's trailing cold front swung through Florida and helped generate a cell that produced a tornado in St. Augustine midday.
The tornado was later confirmed at EF1 strength.
Other thunderstorms produced damaging winds in the North Carolina Piedmont and southwest Virginia.
It appears a tornado touched down in Wilkes County, N.C., near Ronda, about 70 miles north of Charlotte. While the tornado has yet to be confirmed, damage was reported.
Flooding
The same moisture-loaded storm system produced dropped rainfall totals of 1 to 4 inches across the South and parts of the Ohio Valley.
But there were pockets of at least 4 to 8 inches from eastern Texas into central Mississippi and from near New Orleans along the Interstate 10 corridor into the Florida Panhandle.
The most extreme totals, however, were recorded in East Texas near the border with Louisiana.
Doppler radar estimated 14 to 17 inches of rain had fallen there by midmorning Wednesday on the northwest side of Kirbyville in Jasper County.
One rain gauge registered 15.89 inches.
A flash-flood emergency was issued for the greater New Orleans area that same morning.
"It looks like 6 or 7 inches of rain fell on New Orleans,” Jacob Zeringue, a meteorologist at the Weather Service office serving New Orleans, said in an interview.
"We received lots of reports of vehicles being stalled, and the underpasses were largely impassible as well. Lots of flooded roads. Some water got into the businesses.”
Wednesday's rainfall marked New Orleans' third-wettest April day on record.
As the storms progressed eastward, Tallahassee was placed under a flash-flood emergency Wednesday night, with the local Weather Service tweeting "multiple water rescues ongoing and water in structures.”
About 6 to 10 inches of rain were reported.
Then on Thursday night, another flash flood emergency was hoisted in Pennsylvania for southwest Allegheny County and northern Washington County.
The Pittsburgh suburb of Oakdale was particularly hard hit, and the Weather Service reported three swift water rescue teams were dispatched.
Pittsburgh officially received 2.77 inches Thursday, its wettest April day on record - breaking the monthly record of 2.68 inches set just nine days earlier.
"This is the only time the 1st and 2nd greatest daily rainfall for a month have occurred in the same year,” the Weather Service office wrote on X.
Significant flooding also occurred Thursday night in western West Virginia.
Next week's storm setup
While the worst of this week's storm is over, a significant outbreak of severe weather could threaten the southern Plains and Midwest on Monday and Tuesday.
A potent high-altitude disturbance is forecast to swing over a strengthening dryline, along which potent storm cells may form in the Texas Panhandle or western Oklahoma on Monday afternoon.
Then the cells are expected to merge into line segments by Monday night and race east toward Oklahoma City.
On Tuesday, a cold front tied to that same system could bring severe storms from Chicago to near Waco, Tex.
"All severe weather hazards are possible, including tornadoes, damaging wind gusts and large hail,” the Storm Prediction Center wrote.
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