Hurricane Aletta over the Eastern Pacific has rapidly weakened today. A combination of strong wind shear, cooler waters, and dry air has severely taken a toll on the storm, and Aletta is now a minimal Category 1 hurricane with an exposed low-level circulation. Aletta should continue to weaken over the next two days, and will likely become a post-tropical remnant low by Monday afternoon, if not sooner. To the east of Aletta, advisories have been initiated on Tropical Depression Three-E which is likely to become a hurricane by early next week as it parallels the Pacific coast of Mexico.

Aletta on the way out

As of 3:00 p.m. MDT (5:00 p.m. EDT) Saturday, Hurricane Aletta was centered near 16.4°N 113.1°W, and was moving westward at about 6 mph. Maximum sustained winds were 65 knots (75 mph), with an estimated minimum pressure of 984 mb. The intensity of 65 kt is very generous based on the storm’s current rapidly decaying presentation, and I personally think Aletta is now a sheared tropical storm. Aletta’s forecast is straightforward. Moderate shear, cooling sea surface temperatures and a more stable environment should continue the weakening trend. Aletta is expected to become a post-tropical remnant low in about 36 hours, but based on the storm’s rapidly decaying presentation it would not be surprise to see this occur a little sooner. Aletta is no threat to land as it spins down.

Tropical Depression Three-E forms, likely to become a hurricane off the Pacific coast of Mexico

To the east of Aletta, a new eastern Pacific tropical depression has formed to the south of the Pacific coast of Mexico. As of 4:00 p.m. CDT (5:00 p.m. EDT), Tropical Depression Three-E was centered near 12.4°N 101.6°W, and was moving west-northwestward at 9 mph. Three-E should become Tropical Storm Bud tonight or early Sunday, and intensify as it parallels the Pacific coast of Mexico. It is possible that Three-E could pose a threat to the Baja California peninsula, but cool sea surface temperatures of about 24°C (75.2°F) near the tip of the peninsula would likely rapidly weaken the storm if this were to occur.

In the short term, conditions for Three-E look very conducive to intensification. Although wind shear is currently about 15 kt, the shear is expected to decrease to below 10 kt on Monday and this would favor intensification. Sea surface temperatures are currently very warm at about 31°C (87.8°F), and are expected to remain above 27°C (80.2°F) for the next three days. The depression is currently embedded in a very moist environment with mid-level relative humidity values above 80 percent, and this is expected to continue for the next three days or so. The majority of the intensity guidance brings the depression to hurricane strength by Tuesday. As a result, intensification is likely throughout the next 72 hours or so, and rapid intensification cannot be ruled out. Although not explicitly forecast by the intensity guidance, it is possible that Three-E could become a major hurricane. By next Wednesday, Three-E should cross the 26°C (78.8°F) isotherm and steady weakening is likely after that time. Interests in the Baja California peninsula should closely monitor the progress of Three-E.

Atlantic still quiet, but weak Gulf development cannot be ruled out by next weekend

The Atlantic basin currently remains quiet, and the National Hurricane Center (NHC) does not expect any development within the next five days. The 12z Saturday GFS, CMC and ICON models continued to show the possibility of a tropical cyclone developing over the northwestern Gulf of Mexico by next weekend. The GFS model has a major bias in early season Caribbean and Gulf development that often never materializes. The reliable UKMET and ECMWF models, as well as the EPS ensembles continued to show no significant development in their 12z runs. Until the ECMWF and/or UKMET models come on board, the threat of significant development over the Gulf of Mexico remains low at this time.

I will be back with another post on the tropics tomorrow, and we should have Tropical Storm Bud by that time.