PTC 18 expected to become Tropical Storm Philippe, Tropical Storm Selma to bring heavy rains to Central America

PTC 18 expected to become Tropical Storm Philippe, Tropical Storm Selma to bring heavy rains to Central America

Official NHC forecast cone for Potential Tropical Cyclone Eighteen. (Source: National Hurricane Center)

The tropical disturbance over the Northwestern Caribbean Sea, previously known as Invest 93L, has been designated as Potential Tropical Cyclone Eighteen. Eighteen is expected to intensify into Tropical Storm Philippe on Saturday, and is expected to make landfall in western Cuba as a tropical storm.

PTC Eighteen poised to become Tropical Storm Philippe, Tropical Storm Warnings issued for parts of Cuba and the Bahamas

Rainbow loop of Potential Tropical Cyclone Eighteen,
located over the Northwestern Caribbean Sea. (Source: NOAA)

As of 11:00 p.m. EDT Friday, Potential Tropical Cyclone Eighteen was centered near 18.2°N 84.4°W, and was moving northward at about 7 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1005 mbPTC Eighteen is gradually becoming better organized, with the development of some banding features. The disturbance is already producing winds to at least tropical storm force, based on earlier data from an Air Force Hurricane Hunter aircraft. However, the disturbance appears to still lack a single well-defined center of circulation, so it has not been named Philippe as of this time. Eighteen is in a favorable environment for intensification for the next 24 hours or so. During this time, wind shear is expected to remain light, less than 20 knots, with very warm sea surface temperatures of about 30°C (86°F) and mid-level relative humidity values above 60 percent. This gives Eighteen a narrow window to develop into a tropical storm, and if it can develop an inner core, some slight intensification is likely before landfall in northwestern Cuba late Saturday. The National Hurricane Center (NHC) gives PTC Eighteen an 80 percent chance of development, both within 48 hours and five days. The next name on the Atlantic naming list, as noted above, is Philippe. Another reconnaissance aircraft is scheduled to investigate the disturbance on Saturday morning.

Regardless of whether Eighteen develops sufficient organization to be named, it will likely bring heavy rains and tropical storm conditions to Northwestern Cuba and the Northwestern Bahamas, and as a result, Tropical Storm Warnings have been issued for these areas. Since a landfall in South Florida appears unlikely, watches and warnings have not yet been issued for this region. However, South Florida is likely to sea moderate to heavy rainfall as a result of Eighteen.

Selma forms in Eastern Pacific, expected to make landfall in Western El Salvador Saturday as a minimal tropical storm

Rainbow loop of Tropical Storm Selma, located over the far Eastern Pacific. (Source: NOAA)

An area of low pressure over the far eastern Pacific acquired sufficient organization to be designated Tropical Storm Selma – the 18th named storm of the season –  early Friday morning. As of 10:00 p.m. CDT (11:00 p.m. EDT), Tropical Storm Selma was centered near 12.3°N 89.0°W, and was moving northward at about 7 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1005 mb. Selma has not become better organized this afternoon, and strengthening appears unlikely before Selma moves inland into Central America on Saturday due to its current structure and moderate wind shear affecting the cyclone. Selma is expected to make landfall in western El Salvador early on Saturday. The primary threat with Selma, much like PTC Eighteen, is heavy rains. Selma should quickly dissipate over central America by late Saturday evening.

I will be back with another post tomorrow.

 

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