On Friday, the threat of severe weather was at Level 2 out of 5, covering most of the Interstate 20 corridor from Texas to Alabama, including Lufkin, Texas. Baton Rouge. Jackson, Mississippi. Several tornadoes are possible in Montgomery and Mobile, Alabama, Friday afternoon.
Announced by the National Weather Service tornado watch to 9 p.m. CT in southeastern Louisiana, southern Mississippi, and southeastern Alabama. The monitoring area includes Baton Rouge. New Orleans; Gulfport, Mississippi. And mobile.
Much of the same region from northeastern Louisiana to Georgia and even the highlands of the Carolinas are at risk of flooding. The National Weather Service indicates a Level 3 out of 4 Moderate risk for flash flooding and excessive rainfall, particularly near and south of Interstate 20 from Birmingham to Atlanta and south to Montgomery. I am.
A long, narrow zone of low pressure stretches from the Texas-Louisiana border to near Chicago. Ahead, southerly winds pull warm, moist air masses containing unstable or thunderstorm fuel northward. This sets the stage for strong to severe thunderstorms ahead of a cold front that is dragged eastward by the low pressure system.
The jet stream, on the other hand, slices overhead, causing changes in wind speed and direction depending on altitude. Winds from the south and southeast prevail near the ground, while winds from the southwest prevail at high altitude. This means that storm clouds that grow high enough can rotate. If that happens, there could be some tornadoes.
But it's unclear how far north the leading edge of warm air, separated by warm fronts, will reach. This determines the overall extent of the severe storm. Storms forming near a warm front that is expected to extend from Jackson to Montgomery could take advantage of more low-level twists.
Thunderstorms have persisted across Mississippi and north-central Louisiana since midday, spreading eastward and potentially intensifying into the afternoon. “A tornado threat exists from parts of Louisiana to southern/eastern Alabama this afternoon and into tonight,” the weather service wrote. “Large hail and very heavy wind gusts are possible in the same area.”
Severe thunderstorms and the threat of several tornadoes will move into the Southeast on Saturday. Atlanta is in a Level 2 out of 5 danger zone, which stretches from the Florida Panhandle to southern North Carolina. Jacksonville, Florida. Charleston, South Carolina. Savannah, Georgia. and Wilmington, North Carolina.
Heavy rain, flooding in the south
Training rains, or heavy rains that repeatedly fall over the same area, will be a problem in the south. That's especially true in southern Alabama.
Flood watches extend from northern Louisiana to western South Carolina.
Initial rainfall is expected to fall between 1 and 3 inches from northern Louisiana to northern Alabama, before moving into Georgia by Friday night. A second round of heavy rain is expected to follow. This could result in an additional 1 to 2 inches of rainfall, with total rainfall reaching up to 5 to 6 inches.
Some weather models are simulating totals up to 7 inches along the Alabama-Georgia border, which is a legitimate concern. The ground is relatively dry these days and can handle heavy rain, but too much of it can cause flooding.
Heavy rains and coastal flooding in the eastern United States
While this system will be a flooded system for many on the East Coast, remember that it is adjacent to another system that initially follows a route from the Great Lakes to northern New England. before the two star systems merge). This means that there can be two separate precipitation maxima, with less precipitation in between.
One of the largest values could occur in the Carolinas. 2 to 3 inches is possible in South Carolina and 1 to 2 inches in North Carolina. Another maximum is expected from Pennsylvania to Maine, with generally 1 to 1.5 inches expected.
The eastern Mid-Atlantic region, around Washington, D.C., and from Richmond east to the Delmarva Peninsula will experience light rainfall. Washington, Baltimore and Philadelphia are likely to see 0.5 to 1 inch.
Most of the rain is expected to fall in the Southeast and mid-Atlantic from Saturday night into Saturday night, reaching New England from Saturday night into Sunday.
There are also concerns about coastal flooding. The inflow of air into a wide low-pressure zone induces southeasterly winds. This refers to onshore currents that push water onto the coast. Coastal flood watches and advisories are in place for many coastal areas on the Mid-Atlantic coast, with water levels 1 to 3 feet higher than normal, raising concerns about shoreline flooding Saturday afternoon and evening, especially around high tide. Minor to moderate coastal flooding is also possible in parts of coastal New England, primarily on Sunday.
Meanwhile, coastline winds of 40 to 55 mph cannot be ruled out from Delmarva to Cape Cod.
Plowable amounts of snow are expected to fall in the Adirondack Mountains of New York state and high-elevation areas of interior New England from Saturday night into Sunday as cold air moves into the northwest side of the storm.
Jason Samenow contributed to this report.