Tropics Tracker: More Saharan dust and La Nina. Here’s what it could mean

Tropics remain quiet

Saharan dust
Saharan dust

ORLANDO, Fla. – The Atlantic Basin continues to be in a large-scale suppressed phase, which will continue to promote a quiet stretch. In addition to those large-scale features, another large plume of Saharan dust is trekking across the Atlantic.

The presence of the dust also helps to limit tropical development while it’s around.

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Saharan dust

The dust has been in Central Florida skies at times this week, helping to enhance sunrises and sunsets when clouds aren’t around. More dust could making an appearance next week.

La Nina coming back?

Now on to the not-so-good news. You may recall last season a La Nina watch was issued for the peak of hurricane. In a nutshell, when La Nina is present, tropical development is typically enhanced. Earlier this year, La Nina subsided and the atmosphere was in the state in between La Nina and El Nino.

Last week, the Climate Prediction Center issued a La Nina watch, meaning that La Nina is possible within the next six months. There is currently a 45% chance for La Nina to be present for the months of August, September and October. If La Nina does develop, the Atlantic could be in another busy second half of the season.

What is La Nina?

La Nina is a seasonal ocean/atmospheric pattern that develops in the tropical Pacific. La Nina is the cool phase of El-Nino Southern Oscillation, or ENSO. During hurricane season, the phase ENSO is in can strongly impact tropical development far away in the Atlantic Basin.

When El Nino, the warm phase, is present, tropical development is suppressed with increased wind shear and poor atmospheric conditions in the Atlantic Basin.

When La Nina is present, waters along the Equatorial Pacific, off of the coast of Peru, are cooler than normal. This happens because the trade winds strengthen in that region, pushing warm water toward Australia, allowing cooler water deeper in the ocean to come to the surface. This is known as upwelling.

La-Nina is defined when waters in the equatorial Pacific off of the coast of Peru become .5 degrees (or greater) Celsius cooler than normal

When this is occurring, wind shear, which hurricanes do not like, tends to be lower, creating a much more favorable environment for storms to develop.

La-Nina favors a more active than normal hurricane season

This helps to enhance tropical development. Rising air that is needed for thunderstorm development is also promoted in this situation.


About the Author:

Jonathan Kegges joined the News 6 team in June 2019 as the Weekend Morning Meteorologist. Jonathan comes from Roanoke, Virginia where he covered three EF-3 tornadoes and deadly flooding brought on by Hurricanes Florence and Michael.