22 Mar 2022 | 08:35 AM UTC
US: Adverse weather forecast across parts of the South, Southeast, and Ohio Valley regions through at least early March 24 /update 1
Adverse weather forecast across parts of the South, Southeast, and Ohio Valley, US through early March 24. Flooding, disruptions likely.
Event
A large weather system is forecast to bring heavy rain and thunderstorms to parts of the South, Southeast, and Ohio Valley regions through at least early March 24. The storm over Texas and Oklahoma is forecast to track eastwards into parts of Arkansas and Louisiana late March 21 before shifting over to Mississippi and Alabama March 22, bringing the greatest risk of tornadoes to the area. The storm will likely move eastwards, bringing severe weather from the Delmarva Peninsula to the Florida Panhandle March 23 through early March 24. Heavy downpours could trigger flooding, and the storms could spawn tornadoes and hail across parts of the affected area. Parts of the Ohio and Tennessee valleys experienced heavy rainfall over the recent weeks; river levels remain elevated. Additional rainfall over already saturated areas is likely to result in floods and flash floods.
Williamson County, Texas declared an emergency March 21. Multiple tornadoes have been confirmed in parts of central and eastern Texas and Oklahoma, causing much damage. One person has died and at least seven others injured in Northwest Grayson County late March 21. Significant damage has been reported in Elgin, Jacksboro, and Round Rock in Texas, and Kingston, Oklahoma. Authorities estimate that around 60-80 houses have been damaged in Jacksboro. An emergency shelter is located at First Baptist Church in Whitesboro, Grayson County. As of early March 22, more than 52,000 people are without power across Texas, mostly in Houston and Madison counties.
Government Advisories
The National Weather Service (NWS) has issued flood and flash flood watches and warnings across southern and eastern Arkansas, western Louisiana, far eastern Texas, and western Tennessee. Tornado watches are in place across eastern Texas, far southwestern Arkansas, and northwestern Louisiana through early March 22. Authorities are likely to issue additional watches and warnings over the coming hours and days as the storm progresses.
The NWS's Storm Prediction Center has warned of a "Moderate Risk" (Level 4 on a five-tier scale) of severe thunderstorms across portions of southern Louisiana and southern Mississippi, an "Enhanced Risk" for most of Louisiana, most of Mississippi, and western Alabama, and a "Slight Risk" from far eastern Texas into the Florida Panhandle and central Georgia. A "Slight Risk" of severe thunderstorms is in effect across portions of the Southeast region from March 23 through early March 24.
The Weather Prediction Center (WPC) has issued a "Moderate Risk" for excessive rainfall over portions of northeastern Louisiana, northern and central Mississippi, and northwestern Alabama and a "Slight Risk" from far eastern Texas northeastward into far southern Indiana and far southern Illinois as well as eastwards into central Georgia and the far western Florida Panhandle through early March 23. A "Slight Risk" is also in effect for the Florida Panhandle and far southern Georgia. Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.
Severe storms in the "Moderate Risk" (Level 4) regions are forecast to be more numerous, persistent, and widespread than those in the region where a "Slight Risk" (Level 2) has been issued. Storms in the Slight Risk regions are not forecast to be widespread or long-lived. Isolated intense storms are possible; however, widespread damage is unlikely. Isolated intense storms are possible, which may contain hail, damaging winds, and a few tornadoes.
Hazardous Conditions
Heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.
Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.
Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.
Severe weather could also trigger flight delays and cancellations at airports in the region, including but not limited to Louis Armstrong New Orleans International (MSY), Memphis International (MEM), Nashville International (BNA), Dallas/Fort Worth International (DFW), Houston International (IAH), Austin International (AUS), and William P. Hobby (HOU) airports. Hundreds of flights were canceled at Dallas/Fort Worth International (DFW) and Dallas Love Field (DAL) airports, and 90 flights were canceled at Austin-Bergstrom International Airport (AUS) March 21; most flights have since resumed, but lingering disruptions are likely. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.
Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.
Advice
Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Review contingency plans and be prepared to move quickly to shelter if tornado warnings are issued. Charge battery-powered devices in the case of prolonged electricity outages.
