An area of disturbed weather over the western Caribbean, designated Invest 95L, has brought widespread rainfall of one to four inches to Cuba, the Cayman Islands. and Jamaica during the 36 hours ending at noon EDT Saturday, with 3.72 inches falling at a personal weather station in Spanishtown, Jamaica.

This system was close to tropical depression status early Saturday afternoon, and is likely to become Tropical Storm Zeta by Sunday. A NOAA Hurricane Hunter aircraft was investigating 95L on Saturday afternoon to determine if it has become Tropical Depression 28.

Satellite imagery on Saturday showed that 95L had developed a surface circulation to the west of Grand Cayman Island, but dry air to its north was being driven into the core of the system by moderate wind shear of 10-15 knots. This wind shear was tilting 95L’s vortex and keeping the north side of the circulation devoid of heavy thunderstorms. The system was developing low-level spiral bands and good upper-level outflow to the north.

Forecast for 95L

Steering currents are weak in the western Caribbean, and 95L is expected to drift northwest at less than 5 mph through Sunday. A ridge of high pressure will build in to the northeast of 95L by Monday, forcing it on a northwesterly track at a faster 5-10 mph pace into the Gulf of Mexico. It now appears that 95L has moved far enough west to significantly reduce the threat of a direct landfall in South Florida or the Bahamas. By Tuesday, an approaching trough of low pressure over the central U.S. should turn 95L more to the north, with a landfall along the central Gulf Coast on Wednesday the most likely outcome.

Conditions are predicted to remain favorable for development through Sunday, with wind shear a moderate 10-15 knots, sea-surface temperatures a very warm 30 degrees Celsius (86°F), and a moist atmosphere (a mid-level relative humidity of 70-75%). However, there is plenty of dry air over the Gulf of Mexico, and as 95L progresses into the Gulf, the dry air may significantly inhibit development. Sea-surface temperatures will be cooler to the north in the Gulf as 95L proceeds, and wind shear will rise, further challenging development of 95L.

There was modest support for development of 95L from the Saturday morning runs of the GFS and European models and their ensembles, showing that 95L would likely be a tropical depression or tropical storm on Monday in the southeastern Gulf of Mexico or northwestern Caribbean. A few ensemble members of both models predicted that 95L could become a hurricane in the Gulf, though most considered a tropical storm as the likely outcome.

In either case, heavy rains of 2-5 inches from this system will affect Cuba, the Cayman Islands, the northeast Yucatan Peninsula, and Jamaica through Monday. In a 2 p.m. EDT Saturday tropical weather outlook, the National Hurricane Center gave 95L two-day and five-day odds of development of near 100%. The next name on the Atlantic list of storms is the sixth letter in the Greek alphabet, Zeta.

Hurricane Epsilon recurving out to sea

Hurricane Epsilon was steaming northeast at 13 mph at 11 a.m. EDT Saturday, and was maintaining hurricane status, with sustained winds of 80 mph and a central pressure of 958 mb. Epsilon is a large storm, with tropical storm-force winds that extended up to 405 miles to the north of the center. The large wind field was generating large swells, which will be affecting the U.S. East Coast, Atlantic Canada, and the north-facing shores of the Caribbean islands through this weekend.

Epsilon was riding up a warm tongue of water associated with the Gulf Stream on Saturday morning, but will be moving north of the Gulf Stream on Saturday afternoon. By Sunday, Epsilon will be over waters of just 21 degrees Celsius (70°F), when it may pass close and bring rains of 1-2 inches and wind gusts near tropical storm-force to the southeastern portion of Newfoundland, Canada.

Also see: Delta is record-setting 10th named storm to make U.S. landfall in a season

Epsilon will merge with a trough of low pressure to its north on Sunday and transition to a very powerful extratropical storm with winds near hurricane force. Its central pressure on Tuesday, October 27, when it will be a few hundred miles south of Iceland, could be between 936-946 mb, according to the 0Z Saturday runs of the GFS and European models.

Editor’s note: this post was updated at 2 p.m. EDT Saturday with the latest Tropical Weather Outlook info from NHC.

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Posted on October 24, 2020 (12:53pm EDT).