Updated

Updated · CNN · Jul 21

Tropical Storm Bertha Threatens 3 Gulf States as 8 Inches of Rain and 4-Foot Surge Loom

Updated

Updated · CNN · Jul 21

Tropical Storm Bertha Threatens 3 Gulf States as 8 Inches of Rain and 4-Foot Surge Loom

Q: Can a massive Saharan dust cloud stop Tropical Storm Bertha from becoming a major Gulf Coast hurricane?

Probably yes, but not by itself. Forecasters say the environment around Tropical Depression Two, expected to become Bertha, is unfavorable for major strengthening. The key factors are dry air, increasing wind shear and the storm’s broad, poorly organized circulation. A Saharan dust plume matters because it carries very dry, stable air that can choke off thunderstorms and make it harder for a tropical system to build a strong core. That same air mass is also often linked with stronger winds aloft, which increase shear and disrupt storm structure. That said, the dust cloud is not a guarantee that Bertha cannot strengthen. Tropical systems can still intensify if they find a pocket of warm water and remain organized long enough, especially if they stay farther south over the Gulf. The National Hurricane Center outlook indicates gradual strengthening is likely, but rapid intensification is not the favored scenario. Current projections keep Bertha closer to a modest tropical storm, with some forecasts near 50 mph around Louisiana, rather than a major hurricane. So the best reading of the forecast is that Saharan dust is one important reason Bertha is unlikely to become a major Gulf Coast hurricane, but it is part of a broader set of hostile conditions, especially wind shear. Residents should not focus only on category risk: even a weaker tropical storm can still bring dangerous surf, rip currents, storm surge, flooding rain and isolated tornadoes along the Gulf Coast.

3 articles · Updated · CNN · Jul 21

Tropical storm warnings cover coastal Alabama, Mississippi and eastern Louisiana, where Bertha is expected to bring tropical-storm conditions within 36 hours and track toward a late Wednesday landfall near southeast Louisiana or southern Mississippi.
2 to 4 inches of rain, with isolated totals up to 8 inches, are forecast from the western Florida Panhandle to Louisiana and possibly the Texas coast, raising flash-flood risks in low-lying and urban areas including New Orleans.
39-mph-plus sustained winds and 2 to 4 feet of storm surge are possible along parts of the northern Gulf Coast, with higher thunderstorm gusts capable of causing isolated power outages.
Dry air, wind shear and interaction with land are keeping Bertha poorly organized despite very warm Gulf waters, limiting strengthening and possibly weakening it into a depression or even causing dissipation over Louisiana later this week.
Bertha is only the Atlantic season's second named storm, reflecting a slower start that NOAA has linked to El Niño and a forecast for below-average storm activity.