Tropical Storm Nana develops, sets yet another Atlantic record

The Atlantic is showing no signs of losing steam following Laura's wrath along the U.S. Gulf Coast last week, with two new systems forming early this week. Tropical Storm Nana developed in the western Caribbean Sea on Tuesday, joining Tropical Storm Omar in the basin.

Potential Tropical Cyclone 16 was dubbed by the National Hurricane Center at 11 a.m. EDT Tuesday after hurricane hunter planes flew through a "vigorous" system in the Caribbean and recorded 40-mph maximum sustained winds. Just over an hour later, the system was named Tropical Storm Nana as it became better organized with a notable center of circulation visible on satellite. Maximum sustained winds had increased to 50 mph with higher gusts. By late Tuesday evening, maximum sustained winds increased to 60 mph.

This image, captured on Tuesday morning, Sept. 1, 2020, showed that Tropical Storm Nana over the Caribbean Sea had developed both a low-level circulation and a high-cloud structure. Forecasters say the feature was much better organized than it was on Monday. (NOAA / GOES-East)

Nana was churning about 300 miles east of Belize City, Belize, moving westward at 18 mph early Wednesday morning. A hurricane watch and tropical storm warning are in effect for the entire coast of Belize. In addition, a tropical storm warning is also in effect for portions of the Yucatan Peninsula of Mexico

A tropical storm watch is in effect for northern Honduras as well as Roatan Island and the Bay Islands of Honduras, as well as the northern coast of Honduras and the Caribbean Sea coast of Guatemala.

AccuWeather meteorologists say the system, which they have been monitoring for days, could strengthen further as it heads toward Central America.

"Additional strengthening is likely as Nana tracks over warm waters and through an environment with light wind shear. As a result, we expect Nana to become a hurricane before making landfall," AccuWeather's lead hurricane expert Dan Kottlowski said.

The longer the system remains over very warm waters in the region, the greater the chance of additional strengthening prior to landfall.

Heavy rain, gusty winds and rough surf are expected across portions of Central America later this week and into this weekend.

"The greatest threat to lives and property in Central America will be from torrential rain that can unleash flash flooding and mudslides," AccuWeather Senior Meteorologist Rob Miller added.

AccuWeather meteorologists believe the RealImpact™ Scale for Nana will be a 1 due primarily to the storm's small size but also the flooding and mudslide potential. This scale was introduced by AccuWeather in 2019 to better relay the full impact of hurricanes and tropical storms. Unlike the Saffir-Simpson scale, which is based solely on wind speeds, the RealImpact scale factors in other key weather elements.

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Jamaica was affected by Nana into Tuesday night with rounds of heavy rain and gusty thunderstorms. Small craft should remain in port until this system passes to the west on Wednesday.

Heavy rain and gusty winds are expected to target areas from northern Honduras to northern Guatemala, Belize and southeastern Mexico Wednesday into Thursday.

"Wind gusts of 55-65 mph can occur with an AccuWeather Local StormMax™gust of 70 mph," according to Kottlowski.

"Wind of this strength can knock down trees, cause damage to weak structures and lead to power outages," Miller added.

A general 2-4 inches of rain will fall on portions of Honduras, Guatemala, Belize and southern Mexico through Thursday. An AccuWeather Local StormMax™ of 6 inches is forecast.

As the system moves westward, organizes and strengthens, seas will become agitated over the Caribbean, which means that conditions will become rough for small craft. Rough surf is likely along the south shores of the northern Caribbean islands as well as the north shores of South America. Seas and surf will build in the western part of the Caribbean Sea at midweek prior to the system's arrival in Central America.

Soon after the system pushes inland over Central America, it will lose wind intensity, but areas of flooding rain can continue through the end of the week.

"At this time it appears the current Caribbean system will not be a threat to the U.S. as a belt of high pressure that extends westward through the Gulf of Mexico will act as a roadblock and prevent the feature from morning northward," Miller said.

Nana set a new early-season formation record for the letter "N" in the Atlantic when it was named Tuesday. It beat out Nate from the 2005 season, which formed on Sept. 5, for the title.

Tropical Storm Omar followed suit later on Tuesday afternoon and broke the same record for the "O" storm. The previous record-holder was Ophelia from Sept. 7, 2005.

The 2020 Atlantic hurricane season has already generated 16 depressions, of which 15 have become tropical storms, four have strengthened into hurricanes, including one major hurricane. The 2020 season is on record pace that could rival the notorious 2005 season that gave birth to Emily, Katrina, Rita and Wilma.

Early this summer, AccuWeather meteorologists predicted a hyperactive peak hurricane season, which is now underway, and like the notorious 2005 season, Greek letters may be needed beyond the designated list of names for the 2020 season. AccuWeather meteorologists are calling for up to 24 tropical storms and up to 11 hurricanes this season.

Marco was the latest tropical system to set an early-season formation record for 2020. Marco formed on Aug. 20. Even though Marco brought some rain and wind to part of Central America and southeastern Mexico, and briefly reached hurricane status, it was quickly overshadowed by Laura, which prevailed after Marco's demise along the upper Gulf Coast. Laura struck southwestern Louisiana with devastating effects as a Category 4 hurricane early on Aug. 27. Thus far Laura is the only major hurricane for 2020.

Cristobal, Edouard, Fay, Gonzalo, Hanna, Isaias, Josephine, Kyle, Laura and Marco all set new records for their designated letters in 2020. That trend is likely to continue through most letters of the alphabet and perhaps Greek letters as well.

In addition to the feature east of the Carolinas, the area from the coast of Africa to the central Atlantic will have to be watched for development in the coming days.

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