AccuWeather's 2020 Central and East Pacific hurricane season forecast

By Adriana Navarro, AccuWeather staff writer

Updated May. 15, 2020 3:46 PM

As residents who live in hurricane-prone areas of the United States and officials get ready for an intense Atlantic hurricane season and grapple with preparation and sheltering plans in the age of social distancing, the eastern and central Pacific will have a more normal to tranquil season in 2020. However, people who live in Mexico, Hawaii and other susceptible areas of the basin shouldn't let their guard down and write the season off, AccuWeather forecasters warned as they released the 2020 Pacific hurricane season outlook this week.

While the number of major hurricanes expected to develop in the Atlantic Ocean was recently raised from three to four storms to four to six, the East Pacific could spawn three to five Category 3 storms or stronger. A team of AccuWeather long-range meteorologists, headed by Hurricane Expert Dan Kottlowski, forecast 13 to 16 named tropical storms in total to form in the East Pacific, five to eight of which could strengthen into hurricanes. Three direct impacts from either a sideswiping or landfalling tropical storm or hurricane are predicted in Mexico.

"Keep in mind that it takes only one powerful landfalling hurricane to cause considerable damage and potentially loss of life," said Kottlowski, who has been predicting hurricane behavior for 43 years. "This is why even in less active seasons residents and interests along the Mexican coast and even Hawaii should still have a hurricane plan in place."

Tropical Depression 1E churns over the East Pacific to the south and west of Mexico on April 26, 2020, ahead of the official mid-May start to the hurricane season. (NASA / MODIS)

The players in the Pacific Basin won't rely as heavily on the El Niño-Southern Oscillation (ENSO) pattern, or the warm and cool phases of a recurring climate pattern across the Pacific, this season. Later during the summer, the current El Niño pattern may undergo a transition to a weak La Niña.

But since this climate pattern is expected to remain weak, this shift won't be as influential as the water temperatures and wind shear, or winds that change with speed or direction with altitude. Strong wind shear can fan the top part of a hurricane or storm, which can unravel its circulation much like a top behaves

The Eastern Pacific Basin's hurricane season starts earlier than its central counterpart and the Atlantic Basin, beginning on May 15 rather than on June 1. The season got a jump start about 20 days early this year when the Tropical Depression 1E formed well to the south and west of Mexico on April 25. This was the first time that a tropical depression was recorded during April in the East Pacific.

Tropical Depression 1E went down as the earliest storm on record in the East Pacific, but it didn’t strengthen enough to become a named tropical storm. Some of the names that early storms will be given are Amanda, Boris, Cristina, Douglas and Elida. For a complete list of this season’s names and all tropical weather information, visit the AccuWeather East Pacific basin hurricane center.

Any development in May usually takes place far from the coast of Central America and Mexico, making for a low threat to land, according to Kottlowski. There were two storms of note last season: Hurricane Lorena and Tropical Storm Narda, both of which impacted Mexico later on during the season in mid- to late September.

Tropical Storm Lorena trekked along the western Mexican coastline on Sept. 18, 2019. (NASA / EOSDIS)

The Central Pacific Basin is forecast to have a nearly normal hurricane season with an estimated five named storms and two possible hurricanes, one of which might develop into a major hurricane.

Tropical storms during June and July are typically systems that originate over the Eastern Pacific and move westward. This is due to conditions several hundreds of miles east of Hawaii usually being more favorable for development, including warm water and fewer episodes of strong vertical wind shear, according to Kottlowski.

For tropical formation, sea surface temperatures typically need to be no lower than about 80 degrees Fahrenheit, according to Kottlowski. Water temperatures don't usually reach that mark until late July and early August, and the waters can remain warm enough to sustain tropical development into October and November.

While waters are sufficiently warm enough to allow disturbances to brew in the eastern Pacific earlier in the calendar year, the polar jet stream reaches far enough south into the central Pacific to maintain vertical wind shear during May, similar to the Atlantic Basin.

Water temperatures around the Hawaiian Islands are currently cooling due to strong easterly trade winds. Later during the season, the water temperature around the islands can increase some with summer's heat, but easterly trades will tend to keep coastal waters cool to the east of the islands.

"Sea surface temperatures typically run warmer south and west of the islands where the trades are weaker, but given the possible onset of a La Niña and ocean cooling near the equator, sea surface temperatures will be running cooler this season even south of Hawaii," Kottlowski said.

Past hurricanes have shown that the worst-case track for a tropical impact on Hawaii is from south of the islands, which can bring devastation to the more densely-populated areas. Only four hurricanes have brought significant impacts to Hawaii since 1950, including Hurricane Lane in 2018, which approached from the east and curved northward to sideswipe the islands.

The Pacific hurricane season of 2018 produced the highest accumulated cyclone energy value on record in the basin, and it tied fourth with 1982 as the most active year on record. The 10 major systems of the Pacific season caused at least 52 deaths.

During 2019, the Pacific basin's second strongest hurricane, Category 4 Hurricane Erik passed just south of Hawaii, sparing the islands the storm's worst impacts and instead stirring rough surf and brushing the southern side of the Big Island with outer rain bands, according to AccuWeather Meteorologist Courtney Travis.

"It’s going to be more difficult for storms to impact Hawaii this season [due to the cooler water]. This does not mean it’s impossible," Kottlowski said. "One possible scenario is for a storm to form in the East Pacific and become very strong where you see the warmer water then reach Hawaii as a strong but weakening storm. This would be a more typical scenario."

A similar track played out in 2019 when Hurricane Barbara, a Category 4 hurricane with winds up to 155 mph at its peak, approached the islands. The system beat out Hurricane Erik, which packed winds of up to 130 mph, as the strongest storm of the year in the Pacific.

Hurricane Barbara on July 4, 2019. The storm became the strongest storm of the year in both the central and eastern Pacific basins. (NASA / EOSDIS)

"The bulk of the storm's life was in the eastern Pacific," Travis said. "However, the remaining rain and wind from Barbara after it was no longer an organized tropical storm impacted Hawaii and triggered power outages in the state."

Given that there won't be as expansive warm water like during the past two years, Kottlowski said it will be more difficult for storms to impact Hawaii during the 2020 Pacific hurricane season.

The ENSO pattern won't have as heavy a hand in storm development this season as it is expected to remain neutral or have a weak shift from El Niño to La Niña. Normally, a shift like this results in an elevated season for the Atlantic Basin and a calmer season for the Pacific.

"In strong transitions from El Niño to La Niña, the atmosphere tends to have more sinking motion in the East Pacific and more rising motion in the Atlantic," Kottlowski explained. "Rising motion favors thunderstorm development and lower pressure, and this give rise to more activity. However, sinking motion gives rise to higher pressure and less thunderstorm development leading to less favorable weather for tropical development."

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