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A post-Thanksgiving storm could make for messy travel in the eastern U.S.

An unwelcome slop of heavy rain and thunderstorms is working across the country, set to bring flooding to some, the chance of severe weather to others, and even a dose of plowable snowfall to residents in west Texas and eastern New Mexico. It’s the second of at least three back-to-back storm systems traipsing through the Lower 48, part of an active weather pattern that looks to linger into early December.

Most heavily affected will be a broad swath of the Deep South and southern Plains, where a general 2 to 4 inches of rain could bring localized flooding. Some of the heaviest could fall in the greater Houston metro, where flood watches are in effect through Saturday.

The storm isn’t terribly intense, as strong winds and tornadoes won’t be an issue, but it comes during arguably the worst possible time of year as people travel home after the Thanksgiving holiday. During this peak of post-Thanksgiving travel, 55 million Americans are expected to drive 50 miles or more. Millions more will take to the skies or rails. Anytime travel is involved, the weather becomes crucial.

The storm now

The storm is intensifying over the Texas Trans-Pecos and northern Chihuahua, Mexico, where a pronounced counterclockwise swirl can be seen on water vapor satellite imagery. Ahead of the system, comparatively mild, more humid air is swirling north, with chillier Canadian air crashing south in its wake.

Where the moisture and cold air are overlapping, plowable snows are falling. That’s the case in southeast New Mexico, western parts of Texas Hill Country and the Big Bend of Texas. Winter storm warnings are in effect in Marfa, Tex., and Carlsbad, N.M., with a winter weather advisory for Lubbock. The Interstate 10 corridor could be heavily impacted.

Farther to the east, rain was falling on the warm side of the system between Abilene and the Dallas-Fort Worth Metroplex. Additional downpours and a few thunderstorms were lurking offshore of Houston.

Texas flood potential

As the system intensifies, it will draw a tongue of Gulf of Mexico moisture northward. That would lead to a conveyor belt of downpours repeatedly targeting Houston. The National Weather Service Weather Prediction Center has drawn a level 3 out of 4 moderate risk of excessive rainfall and flash flooding around the city.

The local National Weather Service office warns that “rainfall rates up to 2 inches per hour are expected with higher rates up to 4 inches per hour in the stronger and slower moving storms.” That could rapidly lead to serious accumulations that would overwhelm the ground’s ability to absorb runoff, especially in cityscapes and more densely populated areas.

Farther north and west, Austin, Dallas and Longview could see an inch or more, with some slight delays likely along Interstates 10, 20, 30 and 35.

In the Houston to Galveston corridor, also a major hub for air travel, the heaviest rain will come down Friday evening into the first half of Saturday. Anywhere from 2 to 5 inches or more is possible, with the greatest totals coming from downpours that train, or move repeatedly over the same areas.

A level 1 out of 5 marginal risk of severe weather also covers parts of the South Texas coastline, including the Matagorda Peninsula, where a brief, fleeting tornado can’t be ruled out.

Heavy rain across the South and Midwest

By Saturday morning, the strengthening low will shift toward Central Texas, spreading the main axis of moderate to locally heavy rain into Oklahoma, Arkansas, Louisiana and East Texas. A six- to 10-hour window of moderate rains will cross through Mississippi, Alabama and Tennessee during the second half of Saturday into the overnight or early Sunday, while a lighter region of “wraparound” rains pinwheels back west around the low pressure center.

A general 1 to 2 inches of rain is likely across most of the South, with a half-inch to an inch in Tennessee. Parts of the Midwest might see some decent rainfall, too, with a bit more than an inch in most of central and southern Illinois, Indiana and Missouri. Amounts taper off east of the Appalachians.

Sunday rain along the Eastern Seaboard

The Interstate 95 corridor in the Carolinas and Mid-Atlantic will see its rain, about a half-inch to three-quarters of an inch, arrive centered around noontime Sunday, give or take a few hours. It won’t be a washout, but some moderate to heavy downpours can be expected. Lighter rains may reach all the way back to Chicago during the first half of the day Sunday; by Sunday night into Monday, the system will have withdrawn into New England.

This could make for some slow travel in between cities such as Charlotte, Raleigh, Washington, D.C., and New York City. Boston, Providence and Hartford will be most affected after dark.

Source : WashingtonPost