US: Adverse weather forecast across parts of the South through at least early Nov. 21

Severe weather is forecast across parts of the South through at least early Nov. 21. Severe storms with large hail are possible across Oklahoma late Nov. 19. The system is forecast to track eastwards towards the Lower Mississippi Valley Nov. 20, bringing possible damaging winds, large hail, and tornadoes. Widespread rainfall and thunderstorms will broadly expand from the Mississippi Valley Nov. 20 into the Midwest, Ohio Valley, and Tennessee Valley Nov. 21 as the system continues eastward. Some locally heavy rain and isolated flash flooding are possible.

As of late Nov. 19, the National Weather Service (NWS) has not yet issued any watches or warnings in relation to the storm but is likely to as the system approaches. The NWS's Storm Prediction Center has warned of a moderate risk (level 3 on a five-tier scale) of severe thunderstorms across parts of northern Louisiana and central Mississippi and a slight risk across the rest of the affected area Nov. 20-early Nov. 21. Officials will likely update and possibly extend the coverage of weather alerts over the coming hours and days.

Sustained 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 the soil has become saturated by heavy rainfall.

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.

The severe weather may contribute to transport disruptions throughout the region. 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 across the affected region. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas with heavy rainfall and potential track inundation.

Localized business disruptions may occur in flood-hit areas; some businesses might not operate at full capacity because of damage to facilities, possible evacuations, and some employees' inability to reach work sites.