There are two systems to currently watch in the tropics: one in the Atlantic, and one in the eastern Pacific. The eastern Pacific season began three days ago, but the Atlantic hurricane season does not officially begin for two more weeks. Both are given a medium (40%) chance of development by the National Hurricane Center (NHC) over the next five days.

As of 18:00 UTC Saturday, Invest 91E was centered near 12.4°N 93.4°W, and was moving little. Maximum sustained winds were 25 knots (30 mph), with an estimated minimum pressure of 1008 mb. The NHC in their 11:00 a.m. PDT Tropical Weather Outlook (TWO) gave 91E a 10 percent chance of development within 48 hours, and a 40 percent chance within five days. 91E has become significantly better organized than yesterday, and a scatterometer pass this morning indicated that the circulation had become a bit better defined. However, the convection is still somewhat disorganized, and 91E has a ways to go before becoming the 2019 Pacific season’s first tropical cyclone.

Environmental conditions remain quite favorable – 91E is expected to remain over waters warmer than 28°C (82.4°F), and wind shear is expected to remain very light (less than 10 knots) for the next five days. Despite the favorable conditions, model support remains rather limited with 91E in the short term. The 12z ECMWF and GFS model runs do not show significant development with 91E over the next five days, but the system could develop after that. 91E is not likely to move much over the next several days. Interests in the Pacific coast of mainland Mexico as well as the Pacific coast of Guatemala should monitor the progress of 91E. If 91E develops into a tropical storm it will be named Alvin.

Weak tropical or subtropical cyclone may form southwest of Bermuda early next week

An area of disorganized shower activity has developed well east of the Bahamas, and this system could slowly acquire tropical or subtropical characteristics over the next several days as it moves northwestward, and then northeastward. NHC gives this system a near zero percent chance of development within 48 hours, and a 40 percent chance within five days. Model support for this system remains limited, with none of the operational 12z GFS, ECMWF or UKMET models showing development of a tropical or subtropical cyclone with this system. Based on the limited model support, I’d place 5-day tropical cyclone genesis chances with this system lower, at only 20%. If this system becomes a tropical storm, it would be named Andrea.

I will be back with an update on the tropics tomorrow. The tropics are getting more active as we head into the second half of May!