After peaking as a Category 4 hurricane during the early morning hours Tuesday, Hurricane Bud over the eastern Pacific has begun to weaken this afternoon as it moves over cooler waters. Now a low-end Category 3 hurricane, continued weakening is expected for Bud over the next few days before it becomes a post-tropical remnant low by Saturday. In addition to Bud, there is a disturbance to watch over the Caribbean (Invest 91L) and another potential eastern Pacific system.

As of 3:00 p.m. MDT (5:00 p.m. EDT) Tuesday, Hurricane Bud was centered near 18.6°N 108.6°W, and was moving northwestward at about 3 mph. Maximum sustained winds were 100 knots (115 mph), with an estimated minimum pressure of 960 mb. The structure of Bud has significantly degraded during the last several hours, with the eye become less defined and cloud tops around the eye warming. Bud is moving over sea surface temperatures cooler than 27°C (80.6°F), and these ocean temperatures are expected to continue to decrease for the next two days. This should continue the weakening trend, with a gradual erosion of deep convection likely over the next couple days. Bud should weaken to a tropical storm on Thursday and is likely to make landfall in Southern Baja California late Thursday or early Friday as a weak tropical storm. Afterwards, Bud should degenerate into a post-tropical remnant low by Saturday as it moves inland into Mainland Mexico and eventually Arizona. Tropical moisture from Bud’s remnants will reach the Southwestern United States late this weekend and early next week.

91L not very likely to develop due to moderate to strong shear, heavy rain the main threat

A sharp surface trough over the western Caribbean Sea is producing disorganized shower and thunderstorm activity, and has a low chance to gradually develop into a tropical depression by the weekend. As of 18:00 UTC Tuesday, Invest 91L was located near 14.6°N 81.6°W, and was moving generally west-northwestward. Maximum sustained winds were 25 knots (30 mph), with an estimated minimum pressure of 1012 mb. The National Hurricane Center (NHC) gives 91L a 10 percent chance of development within 48 hours, and a 20 percent chance within five days. Environmental conditions are not favorable for significant development. 91L should gradually move west-northwestward over the next several days, moving over the Yucatan peninsula on on Thursday and emerging into the southwestern Gulf of Mexico on Friday. Although sea surface temperatures are above 28°C (82.4°F) and 91L is located in a fairly moist environment, vertical wind shear is expected to remain above 20 knots (25 mph) for the next several days, which will likely suppress development. Of the 12z Tuesday models, only the unreliable CMC model develops 91L into a tropical cyclone, near the coast of Texas. The more reliable GFS, UKMET and ECMWF models show little to no development with 91L. Even though it is unlikely 91L develops into a tropical cyclone, 91L is likely to bring heavy rainfall to much of coastal Texas. In the unlikely event that 91L becomes a tropical storm, it would be named Beryl.

Another disturbance in the eastern Pacific, conditions only marginally favorable for development

The active period over the eastern Pacific may continue, with a broad area of low pressure developing south of the Gulf of Tehauntepec. The NHC gives this disturbance a near zero percent chance of development within 48 hours, and a 20 percent chance within five days. Upper-level winds are only expected to be marginally favorable for development, and model support for the development of this system is limited. The next name in the Pacific hurricane naming list is Carlotta.

I will be back with another update on the tropics tomorrow.