Hurricane Aletta Becomes the First Major Hurricane in the Western Hemisphere in 2018; Second System to Follow

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Hurricane Aletta Remains a Major Hurricane in the Pacific

Hurricane Aletta continues to move away from Mexico in the Pacific. It is not expected to be a threat to land. 

Story Highlights

Hurricane Aletta rapidly intensified to Category 4 intensity.

Fortunately, Aletta is no direct threat to land.

Another area of low pressure to the east will likely also become a named storm by this weekend.

The future of this second system is still somewhat uncertain regarding potential land impact next week.

Some outer impacts such as high surf, rip currents, and bands of rain may affect the coast, regardless.

Hurricane Aletta remains a strong major hurricane, the first of the 2018 Eastern Pacific hurricane season, while another area off the Mexican coast is expected to become the second named storm this weekend.

(MORE: Hurricane Central)

Aletta is centered just over 500 miles south of Mexico’s Baja Peninsula.

In just 24 hours, Aletta went from a tropical storm to a Category 4 hurricane, doubling its maximum sustained winds (70 mph to 140 mph) by the 9 a.m. MDT Friday National Hurricane Center advisory. 

Infrared satellite imagery now shows a distinct, 20-mile diameter eye, with deep convection surrounding it.

(MORE: Why Some Hurricanes Rapidly Intensify, While Others Do Not)

Current Storm Status

Current Storm Status

The highest cloud tops, corresponding to the most vigorous convection, are shown in the brightest red colors. Clustering, deep convection around the center is a sign of a healthy tropical cyclone.

The combination of increased wind shear and quickly decreasing ocean heat content will cause Aletta to quickly weaken this weekend as it moves into the open Pacific.

Fortunately, a dome of high pressure aloft over northern Mexico is steering Aletta away from the Mexican coast on a general west-northwest track the next several days.

Aletta's Current Status and Forecast Path

Aletta’s Current Status and Forecast Path

The red-shaded area denotes the potential path of the center of the tropical cyclone. It’s important to note that impacts (particularly heavy rain, high surf, coastal flooding, winds) with any tropical cyclone usually spread beyond its forecast path.

To the east of Aletta, another area of low pressure, a tropical wave, is given high odds by the NHC to develop into a tropical depression or tropical storm this weekend south of the Mexican Riviera.

(MORE: Why Tropical Waves Are Important During Hurricane Season)

If it eventually becomes a tropical storm, it would earn the name Bud.

Chance of Tropical Development

Chance of Tropical Development

The current location of Aletta (left) and potential area of tropical development (circle at right) over the next five days. An “X” indicates the current location of the disturbance that may later develop.

It’s too soon to determine whether this second system will eventually pose a direct threat to parts of the Mexican Pacific coast next week.

For now, interests along the Mexican coast from Acapulco to Zihuatanejo, Manzanillo, Puerto Vallarta and Los Cabos should monitor the progress of this second system into next week. 

(MORE: Why the Eastern Pacific Hurricane Season Matters For the U.S.)

At least some peripheral impacts are possible near the coast from each system, even if the centers of both systems remain offshore. 

Some outer rainbands will likely push ashore, at times, through next week, possibly triggering local flash flooding if they persist in any area for a few hours at a time.

High surf will be generated, propagating first to the southern Mexican coast, then pushing northward toward the Baja Peninsula, including Los Cabos. Breaking waves and rip currents will be a threat along those beaches into at next week.

(MORE: The Danger of Rip Currents)

The average date when the first named storm forms in the Eastern Pacific Basin is June 10, according to NHC data from 1971 to 2009. An average Eastern Pacific hurricane season sees the first hurricane form by June 26.

It’s not unusual for the Eastern Pacific season’s first storm to be a Category 4 hurricane. It’s happened seven other times since 1970, according to NOAA’s historical hurricanes database.

The 2015 season began with Category 4 Hurricane Andres, followed by Category 4 Hurricane Blanca, the record earliest-in-season second Eastern Pacific hurricane and major hurricane, which later became the record earliest Baja California landfall, as a tropical storm.

However, only one of these “A” hurricanes has reached Category 5 intensity, Hurricane Ava in June 1973, according to NOAA.

Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7. Follow him on Facebook and Twitter and subscribe to The Weather Channel podcast on Apple, Google Play, Stitcher, or wherever you get your podcasts.

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