Kansas to Virginia facing dangerous flood threat as downpours increase
A weather battle zone marking the northern edge of extreme heat and more temperate air will set the stage for torrential downpours to repeat along a 1,200-mile-long zone from Kansas to West Virginia and Virginia this week. The pattern will bring drought and heat relief to some areas, but at a cost that includes the risk of dangerous flash flooding, AccuWeather meteorologists warn.
"Storms that fire from the central Plains to parts of the southern Appalachians and the Northeast will have heat on the run this week," AccuWeather Meteorologist Matt Benz said.
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Temperatures will be slashed by an average of 10-20 degrees following highs well into the 90s to near 100 from last week through this past weekend. Highs ranging from the upper 70s to the low 90s will be the rule much of this week from St. Louis and Kansas City, Missouri, to Roanoke and Richmond, Virginia, thanks to the cooling effects of the downpours.
A heat dome that scorched the central and eastern United States over the past week will be pushed farther south by a persistent weather system that is forecast to stretch from the central Plains to the central Appalachians. In this setup, downpours will train, or repeat, over the same location for several hours -- and many locations will face downpours day after day.
Soon after torrential rainfall concerns were raised on Monday, some locations in the central U.S. began to experience rapid flooding issues. Early Tuesday morning, a swath of very heavy rainfall moved into much of the St. Louis metro area. From 6 to 12 inches of rain fell on the St. Louis area which prompted a flash flood emergency Tuesday morning.
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In a radar image captured at 5 a.m. Tuesday morning, torrential rainfall was falling on much of the St. Louis metro area. As storms moved from northwest to southeast and repeated across the city, inches of rain poured down. |
Heavy rain was still falling around St. Louis during the midday hours on Tuesday and had expanded from Missouri to West Virginia in a narrow zone.
"This will be a long-duration rainfall event, which will bring an expanding risk of flash flooding with time as more downpours occur," AccuWeather Senior Storm Warning Meteorologist Joe Bauer said. The ground is already moist across the eastern Ohio Valley up to West Virginia so the rainfall into Thursday and has the potential to produce major flash flooding in the region.
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A general 2-4 inches of rain will fall through Thursday from southern Nebraska and northern Kansas to southern Virginia and northern North Carolina, forecasters say. The heaviest amounts of 4-8 inches of rain are most likely from central Missouri to central and southern West Virginia, where an AccuWeather Local StormMax™ of 24 inches of rain has the greatest potential to occur.
Virginia got a preview of what is to come when a severe storm sustained damage to helicopters located at the Naval Station at Norfolk Chambers Field in Norfolk, with damage occurring on the deck at the airfield. No injuries were reported during the incident.
"The potential exists for an event similar to the excessive rainfall and flooding that occurred around St. Louis Tuesday morning to develop across areas from Kentucky to southern West Virginia on Wednesday," AccuWeather Senior Meteorologist John Feerick said. People should be prepared to move to higher ground and be on the lookout for flooding while traveling.
Given the localized nature of the rainfall, isolated amounts over 4 inches will be possible in a few spots throughout the entire threat area, such as what occurred in St. Louis. Other cities in the path of torrential rain into at least Wednesday include Evansville, Indiana; Louisville, Kentucky, and Charleston, West Virginia.
Downpours in this zone will slow travel on the highways at the very least and can lead to excess water on the roads in poor drainage areas. Any metro area as well as locations along small streams could still be prone to flash flooding, despite prior drought conditions or dry topsoil.
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The steep hillsides and valleys with streams in the southern Appalachians are highly prone to flash floods. Those spending time camping or fishing along small streams should be aware of the danger for rapidly rising water.
In the most extreme cases, from 1-3 inches of rain may fall in a couple of hours' time. A small stream can transition from a trickle to a raging torrent in a matter of minutes anytime during the day or night with the weather situation this week.
Earlier in July, downpours contributed to flash flooding in two separate locations over the southern Appalachians. At Greenbrier Campground, near Gatlinburg, Tennessee, flash flooding forced hundreds to evacuate and a dozen to be rescued on July 12. The next day, flash flooding produced a path of destruction in rural Buchanon County in southwestern Virginia for miles along Dismal Creek. There were no fatalities in either of the two events.
Flash floods unleashed by training thunderstorms in August of 2021 turned deadly in middle Tennessee with nearly two dozen drowned. Flash flooding from Tropical Depression Fred took several lives in western North Carolina during the same month in 2021.
From Thursday to Saturday, the boundary between very hot air and seasonable temperatures, along which showers and thunderstorms will erupt, will shift southward. The heaviest rainfall will also target areas farther to the south across the Tennessee Valley, according to Bauer. "Additional rainfall can still occur over portions of the southern Appalachians this weekend, which can continue the flooding threat in the region," he warned.
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Rainfall will develop over the lower Mississippi Valley and the southern Plains as the front sags southward from late this week into this weekend. The downpours can provide some drought relief.
Following torrential rain in early June, the area from southern Missouri, northern Arkansas and eastern Oklahoma, particularly around the Ozark Mountains, has received very little rainfall from July 11 to July 24, leaving the ground quite dry. Fort Smith, Arkansas, only received 0.11 of an inch of rain during the five-week period, compared to an average rainfall of 5.69 inches. Springfield, Missouri, and Tulsa, Oklahoma, have not fared much better with 0.18 of an inch and 0.63 of an inch, respectively, for the same period.
The "flash drought" that has developed in parts of Missouri and Arkansas ranges from severe to extreme, according to the United States Drought Monitor report on July 21. Some crops, such as soybeans, grown along portions of the lower Mississippi Valley could benefit from the rainfall - where flooding does not develop - this week.
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The same sagging front, combined with moisture from Mexico, may also come to the aid of the parched landscape farther west in portions of Kansas, Oklahoma and eastern Colorado late this week and this weekend.
Rainfall is likely to remain scarce as extreme heat lingers over much of Texas and western Louisiana.
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