Relentless downpours to heighten flash flood risk in portions of Texas, Oklahoma
The same weather pattern that ushered in a seemingly sudden shift to winter with heavy snow and cold air in the Rockies early this week will continue to deliver rounds of torrential downpours that will raise the risk of flash flooding over parts of central Texas to western and central Oklahoma into Thursday night.
The heaviest rain will pour down west of the Interstate 35 corridor, but some downpours are expected in Laredo, San Antonio, Austin, Dallas and Waco, Texas, as well as Oklahoma City, potentially leading to incidents of flash and urban flooding.
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A large mass of clouds extended from northern Mexico through parts of the Rockies and Midwest on Wednesday morning, Sept. 9, 2020. (CIRA at Colorado State/GOES-East) |
Cities such as Del Rio, San Angelo, Abilene and Wichita Falls, Texas, can expect enough rain for more widespread flooding problems.
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From 1 to 4 inches of rain has fallen from the Big Bend area of Texas to near the Red River along the Oklahoma and Texas border from the storm as of midweek.
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An additional 2-4 inches of rain is likely with an AccuWeather Local StormMax™ rainfall of 9 inches possible where the downpours are the most persistent.
Forecasters and officials are urging motorists to avoid driving through flooded areas as water could be much deeper than it appears, and road surfaces could be washed way underneath. A foot or two of water is enough to cause some vehicles to float or stall.
The National Weather Service tweeted a warning to motorists in the potential flash flood zone on Wednesday morning, "If you approach a flooded roadway: Turn Around, Don't Drown." The NWS explained that "most flooding deaths occur when automobiles are driven into floodwaters."
Low water crossings are particularly dangerous due to the potential for rapidly rising streams or levels already too high to drive through safely.
The rain will have some benefits, however.
"Portions of Texas and the central and southern Plains are in need of moisture, following abnormally dry to severe drought conditions from this past summer," AccuWeather Meteorologist Maura Kelly said.
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The latest United States Drought Monitor map from Thursday, Sept. 3, shows red areas, indicating extreme drought, orange areas, which indicate drought to severe drought conditions, and yellow areas, which depict abnormally dry conditions. (U.S. Drought Monitor) |
Even though the heaviest rain will generally fall east of the hardest-hit drought areas, some rainfall will reach the western portions of Texas, New Mexico, western Oklahoma and western Kansas.
From the central Plains to part of the Upper Midwest, the same pattern will bring less-intense rainfall overall but also unusually cool conditions for early September.
In areas from Emporia, Kansas, to Omaha, Nebraska, and Des Moines, Iowa, the combination of periods of rain and drizzle with a cool air mass in place may keep temperatures in the 50s F through Thursday, compared to normal highs ranging from the middle 70s to the middle 80s.
Just southeast of the wedge of chilly air that extends from New Mexico and western Texas to Michigan, pockets of thunderstorms can occur. Some of these storms can briefly become strong. A few communities could be hit with strong wind gusts and frequent lightning strikes, in addition to a torrential downpour.
The heaviest and steadiest rain will tend to diminish later Thursday into Friday, and drier weather will expand over the region. As pockets of sunshine become more widespread over the central and southern Plains, temperatures will trend upward toward more seasonable levels this weekend.
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