Tracking the Tropics: How do hurricanes form?

Tracking the Tropics: How do hurricanes form?

TAMPA, Fla. (WFLA) — Tropical Storm Dolly, our fourth named storm of the 2020 Atlantic Hurricane Season, was short-lived and is now well on its way to becoming just a remnant area of low pressure.

Dolly formed in a very interesting scenario where the center of an area of low pressure moved over the thin, trailing warm water of the Gulf Stream. The narrow area of warm water off the northeast coastline was just enough, in this case, to strengthen the low pressure and give it tropical characteristics.

Wind speeds briefly reached 45 mph. However, as the center continued to move east-northeast, away from the thin strip of warm Gulf Stream waters, the waters cooled fast to well below the temperatures needed for tropical systems, and the rapid decay of the system began.

As with any tropical system, the main ingredient to begin formation is warm water. Water temperatures near the surface of the ocean must be at least 79 degrees Fahrenheit.

Humid, tropical air is also needed along with light winds in the upper layers of the atmosphere.

The last ingredient in tropical formation is an area of lower pressure, which usually comes in the form of a weak disturbance or a tropical wave.

First, the warm waters begin to heat up the moist air just above the surface. The warmed air then begins to rise. And with rising, humid air, thunderstorms begin to form.

The formation process continues as air rises and cooler air comes in to replace the air that has rose into the thunderstorms. The warm water then heats up the new, cooler air and it begins to rise. Eventually, if all conditions remain the same, a very strong upward motion will develop and air will continuously flow in from all directions.

Due to the spin of the earth and the Coriolis force, the air will begin to spin counter-clockwise and the weak area of low pressure will continue to get stronger. As long as the four main ingredients are near the system, the tropical cyclone will survive and likely get stronger.

If drier air starts to intrude, it inhibits the system. If the upper-level winds become stronger, it could shear the storm apart. Most importantly, if water temperatures drop below the 79-degree mark, there will not be enough heat to warm the air and it would not rise, creating thunderstorms.

This is the reason forecasters look to different regions of the Atlantic, Gulf of Mexico and the Caribbean at different times of the year because the ingredients come together better depending on the month and season.

Areas forecasters watch for tropical development during the month of June.

Saharan Dust

Lastly, the Tracking the Tropics team is continuing to track the dense plume of dry Saharan dust now moving into the Gulf of Mexico. The dust will linger as several plumes are currently moving across the Atlantic. Again, hazy skies are likely while the dust is overhead and colorful sunrises and sunsets are possible.

Tracking the Tropics is keeping you informed throughout the hurricane season. Watch live every Wednesday at 2 p.m. ET for an update.


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