Tropical Rainstorm Olga to unleash flood threat from Gulf Coast to Ohio Valley

By Alex Sosnowski, AccuWeather senior meteorologist

Updated Oct. 26, 2019 10:55 AM'

Former Tropical Storm Olga will unleash torrential rain from the central Gulf coast to the lower Mississippi, Tennessee and Ohio valleys through Saturday.

Tropical Storm Olga formed in the Gulf of Mexico on Friday afternoon but quickly weakened to a tropical rainstorm off the coast of Louisiana on Friday night.

A look at the downpours spreading across the South early Saturday morning as Olga neared the coast.

Despite weakening, Olga will unleash a large amount of rain as it spreads inland across the South.

New Orleans International Airport had picked up over 7 inches of rain as of 5 a.m. EDT Saturday. The airport also recorded a wind gust to 59 mph as a potent band of thunderstorms moved through early Saturday morning. There were multiple reports of trees and power lines down in the area after the strong gust of wind.

A general 3-6 inches of rain is forecast to fall from the central Gulf coast to southern Illinois and southern Indiana with an AccuWeather Local StormMax™ of 8 inches in parts of Mississippi, Louisiana, eastern Arkansas, western Alabama and Tennessee.

Even though long-term drought conditions exist in part of this area and the rain will be beneficial in that respect, the anticipated rainfall is enough to trigger urban and low-lying area flooding.

A flash flood emergency was issued for north-central Terrebonne Parish and northwestern Lafourche Parish early Saturday morning. "This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!" the National Weather Service warning said.

Major urban areas that can expect heavy rain and the risk of street flooding include Jackson, Tupelo and Biloxi, Mississippi; Memphis and Nashville, Tennessee; Jonesboro, Arkansas; Lexington and London, Kentucky; and Lake Charles, Baton Rouge, Shreveport and New Orleans, Louisiana.

It is possible that a couple of tornadoes and waterspouts are produced along the Interstate 10 and 20 corridors into Saturday evening.

Several tornadoes were reported in southern Alabama on Friday evening with some causing property damage. No serious injuries have been reported.

Southeastern Conference college football games in Knoxville, Tennessee, and Lexington, Kentucky, are likely to be wet at least for part of the time on Saturday.

Motorists venturing along portions of Interstate 10, I-20, I-30, I-40, I-55, and I-59 in the South can expect slow travel with poor visibility and excess water on the roads that could affect braking, handling and emergency stopping.

The rain will spread farther north across the Ohio Valley and parts of the central Great Lakes into Saturday night.

While rainfall is forecast to be less intense than that of the South, a general 1-3 inches with an AccuWeather StormMax™ of 4 inches can occur in parts of Indiana, southern Illinois and western Ohio.

The rain and associated low-cloud ceiling can be substantial enough to lead to airline delays in Indianapolis, Cincinnati, St. Louis and Detroit at times.

Rainy conditions are in store for the Big Ten matchup between Wisconsin and Ohio State at Columbus, Ohio, on Saturday. Rain is also expected to move into East Lansing, Michigan, for the Penn State and Michigan State game during Saturday afternoon. Expect drenching rain for the Notre Dame and Michigan matchup at Ann Arbor, Michigan, during Saturday evening.

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While thunder and lightning cannot be ruled out for these games in the Midwest, gusty thunderstorms are much less likely north of the Ohio River.

The back edge of the rain may not push east of the Mississippi River in many areas until later Saturday afternoon and evening.

The rain will end from west to east across the Ohio Valley and central Great Lakes region from late Saturday night to Sunday morning.

As AccuWeather meteorologists have been discussing this week, the bulk of the rain will tend to push up from the southern Appalachians on west.

However, some showers and spotty thunderstorms are forecast to slice eastward across the southern Atlantic seaboard from later Saturday night to Sunday.

For a time Sunday, the rain may be heavy over the southern Appalachians.

There is the likelihood the NASCAR race at Martinsville, Virginia, will be delayed or postponed on Sunday.

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