A Hyperactive 2018 Eastern Pacific Hurricane Season Ends

The 2018 Eastern Pacific hurricane season, which officially ends on November 30, is in the books as the most active on record for accumulated cyclone energy (ACE), with 316.3 units, according to data from Colorado State University. This tops the previous record of 295.2 units in 1992. Reliable data extends back to 1971, the start of the satellite era. ACE is proportional to the square of a named storm’s maximum wind speed summed up over the length of time the storm exists as a tropical storm or hurricane, and is a good measure of destructive potential.

Figure 1. Accumulated cyclone energy (ACE) for the Northeast Pacific for each hurricane season since reliable data began in 1971. This region, sometimes called the Eastern Pacific, is defined here as the area between the International Date Line and the Americas. We have added the record-breaking current value of 316.3 units to the original graphic. Statistics calculated from National Hurricane Center/Central Pacific Hurricane Center best tracks as archived in the International Best Track Archive for Climate Stewardship. Image credit: Colorado State University .

The 2018 season was hyperactive by virtually any measure, with 23 named storms, 13 hurricanes, and 10 intense hurricanes. This is well above the 1981 – 2010 averages of 15 named storms, 8 hurricanes, and 3 intense hurricanes, and not far from the all-time records of 27 named storms (set in 1992), 16 hurricanes (set in 2015, 2014, and 1992), and 11 intense hurricanes (set in 2015). The Eastern Pacific is defined here as the area between the International Date Line and the Americas, including the forecast region dubbed the Central Pacific.

The 2018 Eastern Pacific season also had a remarkable 35 major (Category 3+) hurricane days, shattering the old seasonal record of 24 major hurricane days set in 2015. Three Category 5 hurricanes with 160 mph winds formed in the Eastern Pacific in 2018: Willa, Lane, and Walaka. This ties the record set in 1994 and 2002 for most Cat 5s in one year in the basin. One other Eastern Pacific hurricane, Hector, topped out as a high-end Category 4 storm with 155 mph winds, and has a shot at getting upgraded to Cat 5 status in post-season analysis.

The landfalling and damaging storms of the 2018 Eastern Pacific season

Tropical Storm Bud made landfall near Cabo San Lucas, Mexico with winds of 45 mph on June 15, before progressing into the Gulf of California and degenerating into a remnant low. No deaths or damages were blamed on the storm. At its peak, Bud was a Category 4 hurricane with 140 mph winds.

Tropical Depression Nineteen-E made landfall in Baja California Sur, Mexico on September 18 with top winds of 35 mph, then moved over mainland Mexico on September 20. Heavy rains from the depression caused flooding that killed 4, left 3 missing, and caused $42.5 million in damage.

Figure 2. Rainfall totals calculated from rain gauge and radar data across the Hawaiian islands for the 72-hour period ending at 2 pm EDT (8 am HST) Saturday, August 25, 2018. Image credit: NWS/Honolulu.

Hurricane Lane was the most damaging Eastern Pacific storm of 2018, even though it never made landfall. Insurance broker Aon is estimating damage of over $200 million in Hawaii, with one person killed. Lane peaked as a Category 5 storm with 160 mph winds on August 22 about 350 miles south of the Big Island, becoming just the second Category 5 storm (along with John of 1994) to pass that close to Hawaii. As Lane trekked to the west of Hawaii and weakened, it slowed down, dumping prodigious rains on the islands. The 52.02 inches (1321 mm) recorded at Mountain View on the Big Island made Lane the wettest tropical cyclone on record for Hawaii, and second-wettest tropical cyclone in U.S. history, behind Hurricane Harvey of 2017 (Texas).

September 12, 2018 9:10am HST: Tropical Storm #Olivia became the first Tropical Storm to make landfall on the island on Maui. A short time later at 9:54am HST, Olivia became the first tropical system of any kind to make landfall on the island of Lanai. #hiwx pic.twitter.com/Y62wg9Qwna

— NWSHonolulu (@NWSHonolulu) September 13, 2018

Tropical Storm Olivia made a double landfall in Hawaii, the first named storm on record to do so. Olivia first made landfall on September 12 as a 45-mph tropical storm on the northeast coast of Maui—their first tropical cyclone landfall on record. After zipping across Maui, Olivia made a second landfall on the northeast coast of Lanai, becoming their first landfall on record. Fortunately, Olivia’s floods caused no deaths and only negligible damage, according to Aon. At its peak, Olivia was a Category 4 storm with 130 mph winds.

Tropical Depression Rosa hit the central coast of Mexico’s Baja Peninsula on October 2 with top winds of 35 mph. Flooding from Rosa killed one person in Mexico but inflicted less than $1 million in damage. Rosa’s remnants swept into Arizona, California, and New Mexico, causing flooding that killed three people and caused several million dollars in damage, according to Aon. At its peak, Rosa was a Category 4 hurricane with 145 mph winds.

Tropical Storm Sergio made landfall in western Baja California Sur and Sonora, Mexico on October 13 as a weak tropical storm, causing over $2 million in damage to Mexico. Moisture from Sergio moved over Texas, contributing to heavy rains between October 15 and 20 that killed two and caused at least $350 million in damage. Areas from Dallas/Fort Worth to Austin to San Antonio recorded more than 10 inches of rain; these rains had return periods that ranged from 1-in-50 to 1-in-200 years (a 2 percent to 0.5 percent chance of occurring in any given year). At its peak, Sergio was a Category 4 hurricane with 140 mph winds.

Tropical Storm Vicente was the deadliest storm of the 2018 Eastern Pacific hurricane season, though the storm never made landfall. The remnants of Vicente moved over the Mexican state of Michoacán on October 23, killing at least 14 people in flood-related incidents, including 11 in the state of Oaxaca. Excessive rains prompted several rivers--including the Papaloapan River--to overflow their banks and inundate numerous villages. At its peak, Vicente was a tropical storm with 50 mph winds.

Explosive rapid intensification from low-end tropical storm to Category 5 hurricane in 48 hours -- zooming in on the core of #Willa pic.twitter.com/4XJ9aASOuS

— Stu Ostro (@StuOstro) October 22, 2018

Hurricane Willa made landfall at Isla Del Bosque, Mexico on October 23 as a Category 3 storm with 120 mph winds. Willa was the only hurricane of the 2018 Eastern Pacific hurricane season to make landfall at hurricane strength, and just the 13th major hurricane on record to hit Mexico's Pacific coast. Widespread damage in excess of $50 million occurred in the hardest-hit Mexican states of Sinaloa, Nayarit, Jalisco, Durango, and Zacatecas, and six people were killed. Agricultural damage in the Las Cañas River basin alone was $10 million. At its peak, Willa was a Category 5 storm with 160 mph winds.

Figure 3. GOES-16 visible image of Hurricane Willa at 11:15 am EDT October 22, 2018. At the time, Willa was a Category 5 storm with 160 mph winds. Image credit: NOAA/RAMMB.

Willa among the fastest-intensifying hurricanes on record

Willa intensified in stunningly quick fashion: from a 35-mph tropical depression to a 160-mph Cat 5 storm in just 54 hours. This matches the record rate of intensification from tropical depression to Category 5 strength for the Atlantic, held by both Wilma (2005) and Maria (2017).

Willa’s extraordinarily rapid spin-up brings to mind Hurricane Patricia, which became the strongest hurricane ever recorded in the Western Hemisphere with 215-mph sustained winds on October 23, 2015. Just east of the region where Willa quickly intensified, Patricia strengthened from Cat 1 winds of 85 mph to Cat 5 winds of 205 mph in roughly 24 hours, the most rapid increase in winds ever observed on Earth in that short a period (excluding tornadoes).

Landfalling major hurricanes are uncommon along Mexico’s Pacific coast

Landfalling major Pacific hurricanes are uncommon in Mexico, having occurred an average of once every five years since 1957, according to NOAA’s HURDAT2 database and historical hurricane tracks web site. Of the thirteen Pacific major hurricanes that have made landfall in Mexico since record keeping began in 1949, six were Cat 4s and seven were Cat 3s.

Category 4 Mexico landfalls (Pacific)
----------------------------------------
Patricia, October 23, 2015: 150 mph
Madeline, October 7, 1976: 145 mph
Unnamed, October 27, 1959: 140 mph
Unnamed, October 22, 1957: 140 mph
Kenna, October 25, 2002: 140 mph
Liza, October 1, 1976: 130 mph

Category 3 Mexico landfalls (Pacific)
----------------------------------------
Odile, September 15, 2014: 125 mph
Lane, September 16, 2006: 125 mph
Tico, October 19, 1983: 125 mph
Olivia, October 14, 1967: 125 mph
Willa, October 24, 2018: 120 mph
Kiko, August 27, 1989: 115 mph
Olivia, October 25, 1975: 115 mph

Figure 4. The twelve Pacific major hurricanes prior to Willa of 2018 that made landfall in Mexico since record keeping began in 1949, according to NOAA’s HURDAT2 database and historical hurricane tracks web site.

A period of unprecedented tropical cyclone activity for Hawaii

This year continued the pattern of unprecedented tropical cyclone activity that the Hawaiian Islands has experienced since 2014. Prior to Olivia's landfall this year, only four named systems had made landfall in Hawaii:

--Hurricane Darby made landfall along the southeast shore of Hawaii’s Big Island on July 23, 2016, as a minimal tropical storm (top sustained winds of 40 mph). Damage was minimal and there were no deaths from Darby. Darby made the closest approach on record by a tropical storm to the island of Oahu, which resulted in torrential rains in excess of 10 inches. Darby passed just 40 miles to the south and west of Honolulu with sustained winds of 40 mph. Darby’s formation was aided by ocean temperatures that were more than 1°C (1.8°F) warmer than average.

--Tropical Storm Iselle, which, like Darby, made landfall along the southeast shore of the Big Island, arrived as a 60-mph tropical storm on August 8, 2014. Iselle killed one person and did $79 million in damage.

--Hurricane Iniki made landfall on Kauai as a Category 4 hurricane on September 11, 1992, killing 6 and causing $1.8 billion in damage (1992 dollars).

--Hurricane Dot made landfall on Kauai as a Category 1 hurricane on August 6, 1959, about two weeks before Hawaii gained statehood. Dot caused 6 indirect deaths and $6 million in damage (1959 dollars).

As defined by NHC, landfall requires the center of a tropical cyclone to pass over land. Other hurricanes and tropical storms, most notably Iwa in 1992, have caused significant damage without making landfall. It’s worth noting that four of the six landfalls now on the books for Hawaii (counting the two from Olivia) have occurred in just the last five years! (A 2016 modeling study and another 2018 study found that we could expect to see an increase in hurricanes near Hawaii in coming decades due to climate change; see also Jeff Masters' August 2014 post, Climate Change May Increase the Number of Hawaiian Hurricanes.)

Eastern Pacific hurricane history for Mexico

At least 13 Eastern Pacific hurricanes have each led to at least 100 deaths. The deadliest on record is the Mexico hurricane of 1959, which struck just north of Manzanillo as a Category 4 storm on October 27. Many hundreds of homes were destroyed in and around Manzanillo, and there were at least 1000 direct and 800 indirect deaths. The deadliest hurricane to affect southern Baja California was Liza (1976), which moved near the southern tip of the peninsula before a Category 3 landfall north of Los Mochis on the Mexican mainland on October 1. Heavy rains on the southernmost peninsula led to a dam failure that killed hundreds, part of a total death toll that exceeded 1200. Just eight Eastern Pacific hurricanes have had their names retired because of their landfall impacts in Mexico. The most expensive Pacific hurricane for Mexico was Hurricane Manuel of 2013, which did $4.4 billion in damage (2013 dollars).

Bob Henson contributed to this post.