As a weakening Tropical Storm Marco bears down on the Gulf Coast from southern Louisiana to the Florida Panhandle with heavy rain, storm surge, and gusty winds tonight, a much stronger storm is lurking that could deliver more destructive impacts to the region with just two days of separation.
Tropical Storm Laura was located approximately 55 mi south of the Cuban mainland and had maximum sustained winds of 60 mph as of 2pm ET Monday. Laura was headed west-northwest at 20 mph towards the Gulf of Mexico and is expected to reach its steamy waters by Tuesday morning after crossing rugged land one last time Monday night.
Conditions in the Gulf are ideal to foster Laura's development. Sea-surface temperatures in the upper 80s°F in a low wind-shear environment could result in Laura undergoing rapid intensification, possibly attaining Major Hurricane status –– with maximum sustained winds of at least 111 mph –– in less than 48 hours.
Laura is expected to make landfall Wednesday night as a Category 2 or Category 3 Hurricane somewhere between far southeast Texas and central Louisiana, but impacts from the soon-to-be hurricane will begin earlier. Life threatening storm surge is expected to start building as soon as Tuesday night and the storm's outer-rain bands should move ashore beginning Wednesday morning. Winds will be on the rise in suit, with breezy conditions spreading throughout the Louisiana and southeast Texas coasts Tuesday night and gradually intensifying through Wednesday.
As Laura nears landfall over the northwestern Gulf Coast Wednesday night conditions will rapidly deteriorate. Laura will be a compact storm moving at a somewhat robust pace, meaning extremely life-threatening conditions could develop over the course of just a couple of hours. Life-threatening storm surge, destructive wind gusts, and flooding rainfall are all hazards that residents of coastal areas of southeast Texas and Louisiana should prepare for. Given Laura's fast pace, damaging winds and flooding rain could extend much further inland later this week.
Laura's most notable impacts will be related to the storm's powerful winds. Wind gusts Wednesday night could topple 100 mph within 25 mi of Laura's path. Tropical Storm force wind gusts of at least 38 mph could extend much further –– as far as 200 mi from Laura's center. This could lead to sturdy buildings facing moderate to severe damage to roofs and sidings. Airborne projectiles will contribute to damage even in the sturdiest of buildings. Some structures like marinas, boardwalks, billboards, and mobile homes will be completely destroyed by the wind, storm surge, or combination. Expect widespread electrical system failure, with many coastal communities being completely cut off from the grid.
The dangerous winds will be accompanied by torrential and unrelenting rainfall for multiple hours straight in Louisiana and southeast Texas Wednesday night through Thursday, and in the Lower Mississippi Valley Thursday through Thursday night. The storm's fast motion will spare the Gulf Coast from crippling flooding as with Hurricane Harvey in 2017 and Tropical Storm Imelda in 2019. Still, 4-8" of rainfall with local amounts of 12" are possible over the course of 24 hours, so severe impacts from widespread flooding are nevertheless expected.
Although Laura will begin weakening upon landfall, the fast forward speed will also permit Laura to remain a tropical storm while trekking inland up the Mississippi River, holding on to tropical storm status possibly until as far north as the Arkansas-Missouri border. Similarly heavy rainfall at the Gulf Coast will fall within 50 mi of Laura's center across the lower Mississippi Valley through Thursday night, leading to widespread flash flooding, creeks overflowing their banks, and minor to moderate river flooding of the Mississippi River and its tributaries. Travel for preparation or evacuation is encouraged to be completed by Wednesday morning. A menagerie of airborne debris, ground debris, snapped trees, downed power-lines, and flooding will make traveling extremely dangerous if not impossible for a roughly 8-12 hour period between Wednesday evening and Thursday afternoon across much of far southeastern Texas and Louisiana
Severe Impact on Supply Chain, Logistics, and Transportation Likely
The WeatherOptics proprietary Roads Index and Business Disruption Index both help visually capture and quantify all these impacts from Laura. The Roads Index describes weather-based driving hazards and overall driving danger along roadways on a 1-10 scale, with increasing values denoting increasing driving risk. As in the above loop from our portal, the Roads Index reaches its maximum value of 10 in areas near Lake Charles, LA and Alexandria, LA early Thursdays morning under peak impact from Laura, indicating extreme road danger, including along major thoroughfares like I-10. Expect roads here to be completely impassible either due to the combination of extremely heavy rain and strong winds, fallen and/or falling trees and power-lines, the widespread presence of ground or airborne debris, or significant flooding. Residents are urged to stay home and heed warnings from local officials because it is unlikely emergency responders will be able to help during or immediately after the height of Laura's impacts. The orange-shaded areas represent Roads Index values of 6-8, which denote severe difficulty driving. Roads will generally be passable in these areas, but scattered debris, ponding, strong winds, and low visibility from heavy rain may make driving difficult or dangerous. Overall, travel across much of Louisiana will be difficult and should be avoided if necessary
After deluging the lower Mississippi River Valley, Laura will be picked up by the northern jet stream and quickly lose its tropical characteristics. The jet will likely carry Laura's remnants across the Ohio Valley Friday then towards the Mid-Atlantic or the Carolinas Saturday. But with a ridge of high pressure expanding into the Gulf of Mexico, moisture will be cut off so the resulting rainfall is expected to be much lighter.
While significant impacts from Laura are expected, it should be noted that the track and intensity are still uncertain. Interaction with western Cuba Monday night and whether or not Laura undergoes rapid intensification will both play vital roles in determining the eventual landfall location and strength.