Hurricane Bud weakened to a tropical storm on Wednesday morning as it tracked northwestward over cooler waters. Bud should continue to gradually weaken over the next couple of days as it approaches the Baja California peninsula. To the east of Bud, an area of low pressure has developed (designated Invest 93E) and could gradually develop into a tropical depression by Saturday. Invest 91L remains active over the Northwestern Caribbean, but is unlikely to develop into a tropical cyclone due to strong wind shear. The recent uptick in tropical activity appears to be associated with a Convectively Coupled Kelvin Wave (CCKW) which has recently passed the eastern Pacific and western Atlantic.

Cooler waters taking a toll on Bud, expected to make landfall in Baja California late Thursday or early Friday

As of 12:00 p.m. MDT (2:00 p.m. EDT) Wednesday, Tropical Storm Bud was centered near 19.6°N 108.8°W, and was moving north-northwestward at about 5 mph. Maximum sustained winds were 50 knots (60 mph), with an estimated minimum pressure of 994 mb. Bud currently consists of a well-defined center with a ring of moderate convection surrounding it. Bud is crossing the 26°C (78.8°F) isotherm today, and the deep convection should continue to decrease over the next two days as the tropical storm weakens. Bud is expected to make landfall along the southern Baja California Peninsula late Thursday or early Friday, and a Tropical Storm Warning has been issued for this region. Bud should only be a weak tropical storm or perhaps even a tropical depression when it reaches Baja California. Bud should become a post-tropical remnant low by Saturday as its circulation interacts with the rough terrain of Mexico. Bud’s remnants are expected to spread tropical moisture throughout northern Mexico and the southwestern United States this weekend.

93E quickly organizing, could become a tropical depression late this week

A broad area of low pressure located southwest of the Gulf of Tehauntepec has been designated Invest 93E by the National Hurricane Center (NHC), and has a medium chance to become a tropical depression by the weekend. The NHC gives 93E a 40 percent chance of development within 48 hours, and a 50 percent chance within five days.

As of 18:00 UTC Wednesday, Invest 93E was located near 11.4°N 98.6°W. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1008 mb. An ASCAT pass from Wednesday morning indicated that the circulation of 93E had become much better defined, and 93E could become a tropical depression by Saturday. The 12z Wednesday GFS model develops 93E into a tropical storm, while the ECMWF, UKMET and CMC models are weaker. Conditions appear marginally favorable for development, with wind shear light to moderate (about 15-20 knots), sea surface temperatures a very warm 30-31°C (86-87.8°F), and mid-level relative humidity values near 80 percent. The next name on the 2018 Eastern Pacific naming list is Carlotta.

91L very poorly organized, development not likely

Invest 91L over the Northwestern Caribbean Sea has not become any better organized since yesterday, and development of this system into a tropical cyclone appears unlikely at this time. The NHC continues to give 91L a near zero percent chance of development within 48 hours, and a 20 percent chance of development within five days.

As of 18:00 UTC Wednesday, Invest 91L was located near 18.2°N 87.2°W, and was moving generally west-northwestward. Maximum sustained winds were 25 knots (30 mph), with an estimated minimum pressure of 1012 mb. 91L currently consists of disorganized showers and thunderstorms with no low-level circulation. Environmental conditions remain unfavorable for significant development. Despite warm waters and a fairly moist environment, strong wind shear of over 20 knots (25 mph) is expected to affect the system for the next few days. Although the wind shear could decrease a bit by the weekend when the system moves into the southwestern Gulf of Mexico, global models continue to show little development. Only the unreliable CMC model develops 91L into a tropical cyclone, with the 12z GFS, ECMWF and UKMET models all keeping 91L a weak disturbance. Regardless of development, 91L is likely to bring heavy rainfall to the eastern Texas coast late this weekend. In the unlikely event that 91L becomes a tropical storm, it would be named Beryl.

I will be back with another post tomorrow.