| Above: TD 15 organizing between Cabo Verde and the coast of Africa, as seen by the VIIRS instrument on the Suomi satellite on Monday afternoon, October 14, 2019. Image credit: NASA. |
A well-organized tropical wave that moved off the coast of Africa on Sunday was designated Tropical Depression 15 by the National Hurricane Center at 5 pm Monday. Moving slowly northwest toward Cabo Verde (Cape Verde) with top sustained winds of 35 mph, the wave has a high degree of spin and an expanding area of heavy thunderstorms that were steadily growing more organized, as seen on satellite images.
Sea surface temperatures (SSTs) were a warm 28°C (82°F) and wind shear was low, less than 10 knots, on Monday afternoon—favorable conditions for continued development. As was the case with so many systems in 2019, the depression formed over unusually warm SSTs, about 0.5°C (1.0°F) above average for this time of year.
The next name on the Atlantic list of storms is Nestor. The system does not have a lot of time to develop, though, since wind shear is predicted to rise to a very high 25 – 40 knots on Wednesday. The most likely prospect is that TD 15 becomes a weak tropical storm as it moves through Cabo Verde, possibly making landfall on one or more islands on Tuesday or Wednesday, then dissipates toward the end of the week as it moves on into greater wind shear and encounters cooler waters.
Tropical Depression 15 has formed in the far eastern tropical Atlantic (20.2°W). This is the farthest east that a tropical depression has formed in the tropical Atlantic (<=23.5°N) this late in the calendar year on record. Old record was 26°W set in 1978. #hurricane pic.twitter.com/It98R6BZ39
— Philip Klotzbach (@philklotzbach) October 14, 2019
If TD 15 becomes Nestor, it will be the latest-in-the-year tropical storm in NOAA's historical hurricanes database to form east of Cabo Verde. The current record-holder is Tropical Storm Ginger, which was named on October 5, 1967, while tracking between Cabo Verde and Africa. Only one other tropical cyclone has been recorded east of Cabo Verde in October or later: an unnamed depression that developed near 11.5°N and 18.0°W on October 5, 1972. That depression survived until October 15 on a broad recurving path that took it into the central North Atlantic. Another tropical depression formed on October 13, 1978, at 26°W, just northwest of Corvo Island in Cabo Verde. Neither of those depressions went on to become tropical storms.
NHC is also watching a tropical wave in the central Atlantic, and another near the coast of northwest Honduras. Both systems are unlikely to develop, with NHC giving them a 20% chance over the next five days in the 2 pm EDT Monday tropical weather outlook. It's much more likely that a tropical depression will form later this week off the Pacific coast of Guatemala and southern Mexico, but that system will be hindered by proximity to land.
A humorous look at the weather industry
On Sunday night, HBO’s "Last Week Tonight with John Oliver" aired a humorous and informative piece on the weather industry. The episode discussed the still-pending nomination of the former CEO of AccuWeather, Barry Myers, to be the head of NOAA—a topic we discussed in a Category 6 post two years ago, when Myers was first nominated. Mr. Oliver mostly put the right spin on the issue—though he had the cloud pattern on the "Superstorm Barry" icon spinning the wrong direction for a Northern Hemisphere hurricane. Of course, this may have been intentionally done to show that Myers' nomination was putting the wrong spin on where NOAA should be going, in Mr. Oliver’s view.
Bob Henson contributed to this post.
