US: Adverse weather forecast across parts of southern US through early May 12 /update 3

Event

Thunderstorms with rounds of strong winds, hail, and possible tornados are forecast to occur across portions of the southern US through early May 12. The affected area includes central, eastern, and southern Texas, far southern Oklahoma, southern Arkansas, Louisiana, Mississippi, southern Alabama, southern Georgia, and northern Florida. The Storm Prediction Center (SPC) has issued a "Slight Risk" (Level 2 on a 5-tier scale) forecast for severe weather for southern Texas for May 11-early May 12. However, storms in this region are not forecast to be widespread or long-lived. Isolated intense storms are possible, which may contain hail, damaging winds, and a few tornadoes.

Heavy rainfall and flooding will be an additional threat for the southern US. As a result, the Weather Prediction Center (WPC) has issued a "Slight Risk" for excessive rainfall for eastern Texas, Louisiana, far southern Arkansas, and southern Mississippi, and far southwestern Alabama, where the heaviest rainfall is forecast. As of May 11, officials with the National Weather Service (NWS) have issued flood and flash flood watches and warnings across portions of far eastern Texas, Louisiana, far southern Arkansas, far southwestern Alabama, far western Florida Panhandle, and far southern Mississippi. Officials could update and possibly extend the coverage of the relevant weather alerts over the coming days.

Hazardous Conditions
The storms will be capable of producing heavy downpours, damaging winds, hail, and tornadoes across the affected area through at least early May 12. Should sustained heavy rainfall occur, it could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of 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. Disruptions to electricity and telecommunications services are possible where significant flooding, landslides, or strong winds impact utility networks.

Transport
Floodwaters and debris flows could render some bridges, rail networks, or roadways impassable, impacting overland travel 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 intermittent flight delays and cancellations at regional airports, though these are unlikely to be severe or prolonged. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track inundation. Localized business disruptions may occur in low-lying areas.

Advice

Monitor local media for weather updates and related advisories. Out of an abundance of caution, confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where adverse weather has been forecast. Charge battery-powered devices in the case of prolonged electricity outages. Review contingency plans and be prepared to move quickly to shelter if tornado warnings are issued.

Resources

NWS Tornado (Twitter)
US National Weather Service (NWS)
US Road Conditions