Atlantic Tropics Heating Up
Five Disturbances Are Being Watched from the Gulf of Mexico to Africa’s West Coast
MIAMI, FL – Although nobody thought that a tropical system would impact California before places like Florida, North Carolina, and Texas, the Atlantic Tropics are heating up. There are currently five disturbances being watched from the Gulf of Mexico to just off the West Coast of Africa. Among these disturbances are Tropical Depression Six and Tropical Storms Emily and Franklin.
Prior to the rapid ramp-up of activity across the Atlantic Basin over the past several days, there had only been four named storms and one hurricane. Hurricane Don, the strongest and last of these four initial tropical cyclones in the Atlantic, dissipated on July 24th. So, there had not been a named system in the Atlantic for 27 days. Last year, there was a drought of named storms for nearly two months, but things quickly changed on the first day of September 2022.
Atlantic Basin Entering Peak Season
This is a signal that the tropics are picking up, and the Atlantic is now entering the peak season. The statistical peak of the Atlantic season is usually on September 10th, but activity does begin to pick up in Mid-August. Some of the most powerful hurricanes emerged in the middle of the Dog Days of August. Most notable are Andrew (1992), Camille (1969), and Katrina (2005). Believe it or not, only about 20 percent of the Atlantic Hurricane Season has been completed.
This is the time when the classic Cape Verde or Cabo Verde storms emerge in the Eastern Atlantic. These often become the killer storms that are remembered throughout history. Some examples would be the Galveston Hurricane of 1900, the Labor Day Hurricane of 1935, the Long Island Express of 1938, Allen (1980), Gloria (1985), Gilbert (1988), Hugo (1989), and Floyd (1999).
Why Classic Storms Emerge Now?
The reason these classic storms emerge during the period of mid-August to early October is the lag in ocean temperatures. The sea surface temperatures are most ideal at this time throughout the Atlantic Basin, particularly in the Eastern Atlantic. However, the 2023 season has behaved much differently than usual. Sea surface temperatures have mostly been above normal throughout much of the Atlantic Basin. Water temperatures just off South Florida have reached 100 degrees this summer.
While the water temperatures have been above normal this season, the upper-level dynamics may not be. With the emergence of at least a moderately strong El Niño this summer, more shearing winds may develop across the Atlantic tropics. This wind shear may negate the impact of above-normal sea surface temperatures and ultimately hinder tropical development. As powerful as tropical storms and hurricanes may be, they can still be delicate and fragile, especially in their early stages.
Conditions Need to be Just Right
Hurricanes, especially the classic Cape Verde Storms that can reach levels up to Category Four or Five on the Saffir-Simpson Scale, need conditions to be just right. In other words, they need adequate water temperatures of 80 degrees or higher and light upper-level winds. The latter ingredient is perhaps the most important since tropical cyclones are barotropic systems that are vertically stacked.
What is meant by vertically stacked clouds is that the cumulus clouds build vertically like layers of a layer cake. If the upper-level winds or hostile, or very fast from the west, Atlantic tropical systems will have difficulty developing. An example is how the jet stream can slow the advance of a commercial jet plane flying from New York to the West Coast. The upper-level winds can also move too fast from the east, which causes the center of circulation to outrace the cluster of storms trying to develop around it.
Will Warm Ocean Temps Overcome El Niño?
The question on most people’s minds as we head into the peak portion of the Atlantic Hurricane Season of 2023, is which will win out, the emerging El Niño, or the above-normal sea surface temperatures throughout the Atlantic basin? Perhaps it depends on the timing and the strength of the El Niño. With the plethora of activity in the Eastern Pacific, it definitely appears that El Niño is here. Hilary’s impact on Southern California and the Southwest is proof.
So, the 2023 season should come down to how much influence will this edition of El Niño have. Especially, on this current crop of storms, and others expected to follow. Of the three tropical cyclones that have developed in the Atlantic over the next 24 hours, Franklin appears to be the most robust at the moment. TD Six is expected to gradually weaken and dissipate over the next day. In addition, Tropical Storm Emily is forecast to turn more to the north and northeast and only threaten shipping interests.
Tropical Storm Franklin and Invest 91L
Franklin is currently moving to the West-Northwest. This track would usually lead it into the more unfavorable area of the Central Caribbean. However, the latest forecast guidance suggests that the storm will continue on its West-Northwest track for about another day. Then, Franklin should make a sharp turn to the north, and approach Hispaniola (Haiti and the Dominican Republic) on Wednesday.
Closer to home, the tropical disturbance in the Gulf may be one of immediate concern. Due to its close proximity to land, and the unusually warm water (even by Gulf and South Florida standards), this disturbance needs watching. Invest 91L is located to the west of Key West in the Florida Keys and near the Dry Tortugas. As of 8:00 PM EDT on Sunday, the NHC gave this disturbance a high chance (70 percent) to develop within the next 48 hours to 7 days.
New Disturbance Off Africa
Lastly, a new disturbance has moved into the Eastern Atlantic. A tropical wave is located southeast of the Cape Verde Islands (Cabo Verde Islands). This tropical wave has a large, but disorganized area of showers and thunderstorms associated with it. However, the NHC indicates that environmental conditions will be favorable for development over the next week. It’s also possible that this disturbance could become another depression later this week. Odds for formation are 20 percent within 48 hours, but 60 percent over the next 7 days.