Here we go again: New tropical storm about to pop over the Atlantic
The ninth named storm of the season will produce potentially life-threatening flooding and mudslides across parts of the Caribbean.
With Gonzalo and Hanna hardly even a distant memory, a new tropical threat has emerged in the Atlantic basin and it is expected to rapidly strengthen. A broad area of showers and thunderstorms — a feature that forecasters have been monitoring for tropical development for days — became better organized on Tuesday. The National Hurricane Center (NHC) designated the area Potential Tropical Cyclone Nine at 11 a.m. EST.
At that time, the system was located about 400 miles east of the Windward Islands with maximum sustained winds of 40 mph — and was moving west at 23 mph. As of early Wednesday morning, the system was located near the island of Dominica in the Leeward Islands with maximum sustained winds of 45 mph, and was moving west-northwestward at 23 mph.
AccuWeather meteorologists say Potential Tropical Cyclone Nine is likely to soon become the next tropical depression and storm of the 2020 season — and it could remain a viable threat for the next five to 10 days.
Tropical storm warnings were issued for Puerto Rico and the U.S. Virgin Islands in advance of the developing system late Tuesday morning. The government of Antigua also issued tropical storm warnings for Antigua, Barbuda, the British Virgin Islands, Montserrat, St. Kitts and Nevis.
Late Tuesday evening, the government of the Bahamas issued a tropical storm watch for the Turks and Caicos Islands. The government of the Dominican Republic issued a tropical storm watch for a portion of that country.
By early Wednesday morning, the tropical storm watch was extended into the southeastern Bahamas, and a tropical storm warning had been issued for the north coast of Haiti.
Unlike Gonzalo, which was a very compact storm that developed in a similar area, the thunderstorms associated with the area under investigation extends along a swath of ocean approximately 700 miles long. In comparison, Gonzalo's tropical-storm-force winds only extended across a distance of 50 miles.
Potential Tropical Cyclone Nine churned about 55 miles west-southwest of Dominica and about 350 miles southeast of Puerto Rico early Wednesday, July 29, 2020. (NOAA GOES East)
Despite the size of the budding system, there have been hurdles for it to overcome for development. And even though its 45-mph sustained winds met the criteria for a tropical storm, the system's lack of a well-defined center is keeping forecasters from upgrading it to a tropical storm status. However, it may soon enter an atmosphere with more favorable conditions for strengthening.
"Moderate wind shear over the feature and dry air to its north has prevented the broad area of thunderstorms from becoming better organized the past few days," AccuWeather Senior Meteorologist Rob Miller said. Strong wind shear, or the changing of winds with altitude, can limit tropical development and even tear apart organized systems, causing them to weaken.
"As this feature moves briskly along to the west-northwest, wind shear is forecast to weaken, which should allow a better-defined center to take shape," Miller explained.
AccuWeather meteorologists expect the disturbance to become the storm of the 2020 Atlantic hurricane season. If it strengthens into a named storm, it would be called Isaias, pronounced ees-ah-ee-ahs. This name was added after Ike was retired in 2008 but has not yet been used. Should the tropical storm form prior to Aug. 7, it would set another early-formation record the season. Irene from 2005, holds the title for earliest ever "I-storm" in the basin.
A NOAA hurricane hunters aircraft is scheduled to fly into the region for further investigation and when meteorologists are able to detect where the center of the feature is situated, that information could be key in determining where the system may track and the impact thereof in the coming days.
If the center of the disturbance was to take shape on the northern part of the mass of moisture, then there would be a greater chance for the system to take a curved path to the northwest, north and then northeast, but perhaps east of the United States over the next seven to 10 days.
Should the center organize much farther south, then there is a more likely chance for the system to pass near or right over the islands of the northern Caribbean from the Lesser Antilles as well as Puerto Rico, Hispaniola and Cuba later this week and this weekend.
This land interaction, especially the mountainous terrain of the larger islands, would exert a drag on the feature and would tend to take the edge off the overall strength. Such a close track over the islands of the northern Caribbean would also raise the risk to lives and property from flooding rain, mudslides and strong winds.
The feature is expected to gradually gain strength over the next couple of days.
"A large portion of the Leeward Islands, Puerto Rico, and northern sections of the Dominican Republic should prepare for wind gusts of 40-60 mph, regardless of the exact track of the center," according to AccuWeather Meteorologist Randy Adkins.
"Damage to some trees, poorly constructed buildings and temporary structures should be anticipated and power outages may result which could last several days in more remote areas," Adkins added.
An AccuWeather Local StormMax™ wind gust of 80 mph is possible, most likely over Puerto Rico.
The high mountains on Hispaniola, and to some extent Puerto Rico and Cuba, act as a natural barrier to the path of the storm. Tropical systems generally avoid tracking over the heart of these islands as a result. However, the mountains can cause the center of an approaching tropical storm or hurricane to jump from one coast to the other and re-form in the process.
The overall strength of the system may also determine its fate as far as a track is concerned. Early on, a well-organized, stronger system is more likely to curve northwestward and northward faster than one which remains poorly organized and stays weak.
"At this juncture, the realm of possibilities of potential tracks for this system range from the Gulf of Mexico to waters east of the United States and Canada and includes all areas in between," Miller said.
It matters where the center forms, how quickly it develops and how strong it becomes before a call can be made for the Gulf, the U.S. or a near-miss for the U.S.
AccuWeather Chief Broadcast Meteorologist Bernie Rayno said that whether or not Florida sees impacts depends on whether the storm moves over Hispaniola, where he said it could fall apart. If it stays north of the island and maintains a circulation over water, however, "There could be some development or certainly moisture approaching Florida, or even [elsewhere on] the southeast coast of the United States," he said.
Other factors to those already mentioned include the amount of wind shear near North America which is never in a steady state. A non-tropical system, associated with a dip in the jet stream, may also help to steer the system to the north and northeast once it approaches the U.S.
Waters over the northern Caribbean, western Atlantic and in the Gulf of Mexico are sufficiently warm to not only sustain a tropical system but also potentially add to its strength.
Either way, the mass of moisture will cause an uptick in drenching downpours and gusty thunderstorms that will spread westward through the Leeward and Windward islands at midweek, followed by Puerto Rico, the Dominican Republic, Turks and Caicos, eastern Cuba and the southeastern Bahamas late this week and into this weekend.
"Rainfall amounts of 2-4 inches will be common across the Lesser Antilles, Puerto Rico, and the Dominican Republic. Locally higher amounts of 4-8 inches with an AccuWeather Local StormMax™ of 10 inches are possible over the higher terrain, particularly over Puerto Rico. Flash flooding is likely to result in a number of areas with mudslides a threat along the hills and mountains," Adkins said.
All interests from the northern Caribbean to the Bahamas, Bermuda, the U.S. and northeastern Mexico should monitor the progress of this feature, which is destined become the next named tropical system and perhaps the next hurricane in the Atlantic for 2020.
AccuWeather's top hurricane expert Dan Kottlowski, assisted by Lead Long-Range Meteorologist Paul Pastelok and other team members, has been studying the anticipated weather conditions for the months ahead and will be issuing an update to the numbers of tropical storms, hurricanes, major hurricanes and direct-U.S. impacts for the Atlantic season this week.
Thus far the 2020 season has outpaced the formation speed of the 2005 season, but not so much in terms of the number of hurricanes thus far. Hanna became the first hurricane of the Atlantic season early on July 25 and also became the first hurricane to strike the U.S later on the 25. By the time Hanna became a hurricane, the 2005 season has already spawned three hurricanes -- Cindy, Dennis and Emily. Both Dennis and Emily became major hurricanes with peak winds of 150 and 160 mph respectively. Hurricane Irene would follow in August in 2005. Irene peaked with maximum sustained winds of 105 mph, which is a Category 2 hurricane.
A map shows eight tropical systems that have developed in the Atlantic basin in 2020 and the tracks they took. (AccuWeather)
Disturbances are lining up over Africa and moving westward with one feature every one to three days apart. This series of disturbances is known as the Cabo Verde part of the hurricane season and is just beginning to ramp up.
Most likely more early-season formation records will be set in the coming weeks with 2005 holdings being swapped with 2020 newcomers. Following Irene's record from Aug. 7, the "J-storm" record is currently held by Jose on Aug. 22, 2005 with the "K-storm" record held by the infamous Katrina on Aug. 24, 2005.
The 10th and 11th names on this year's tropical list, should they be needed, are Josephine and Kyle.
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