Updated

Updated · The Weather Channel · Jul 16

Gulf Low Could Become Tropical Storm Bertha Near Florida as Heavy Rain Threatens Through Early Next Week

Updated

Updated · The Weather Channel · Jul 16

Gulf Low Could Become Tropical Storm Bertha Near Florida as Heavy Rain Threatens Through Early Next Week

Q: How does a massive dust cloud from the Sahara Desert help shield the United States from powerful hurricanes?

A massive Saharan dust cloud helps shield the United States from powerful hurricanes by making the Atlantic much less favorable for storm formation and strengthening. The dust plume, known as the Saharan Air Layer, carries very dry, dusty air from Africa across the tropical Atlantic. Hurricanes need deep tropical moisture to build thunderstorms around a developing center. When this dry air mixes into a tropical wave, it can choke off thunderstorm growth and disrupt the storm’s core. It also often comes with stronger winds aloft, increasing vertical wind shear. That shear can tilt or tear apart a developing system before it becomes organized. In addition, the Saharan air mass is warm and stable, which suppresses the rising motion needed for clouds and storms to intensify. Some research also shows thick dust outbreaks can slightly reduce sunlight reaching the ocean surface, limiting warming and trimming some of the fuel hurricanes rely on. The effect is usually modest, but it can add to the overall suppression. That is why forecasters say the tropical wave now moving off Africa faces poor odds of development: strong wind shear and dry Saharan air are expected to hinder organization. The dust does not eliminate hurricane risk, but it can reduce the number of Atlantic systems that survive long enough to threaten the U.S. It can also bring hazy skies and poorer air quality along the Gulf Coast and Southeast even while helping hold tropical development in check.

3 articles · Updated · The Weather Channel · Jul 16

A low-pressure area is expected to form in the northeastern Gulf by Saturday or Sunday and could strengthen into a tropical depression or Tropical Storm Bertha near Florida this weekend or early next week.
Upper-80s water temperatures in the northeast Gulf and off the Southeast coast could fuel thunderstorms, though limited time over water may keep the system from gaining much strength.
Northern and central Florida face the highest risk of locally soaking rain from this weekend into early next week, with heavier bands also possible from Florida into the Carolinas.
That rain threat stems partly from a weakening frontal boundary, and forecasters warn stalled downpours could trigger localized flash flooding, especially in urban areas.
Forecasters say the main concern for now is rainfall rather than wind, but the setup bears watching because conditions can change quickly during hurricane season.