Jeff Masters Weather Blog

Otis gains strength as it approaches the southern Mexican coast » Yale Climate Connections

The Pacific waters south of Mexico – warmed by a strong El Niño event atop long-term climate change – are spawning yet another landfalling hurricane. As of 11 a.m. EDT Tuesday, Tropical Storm Otis was located about 155 miles south-southeast of Acapulco, continuing on a steady north-northwest pace at 8 mph. Otis’s top sustained winds were up to 70 mph, and the National Hurricane Center predicts that Otis will reach hurricane strength on Tuesday before making landfall on Wednesday. A Hurricane Warning was in effect for most of the coast of Guerrero state, including Acapulco.

Strong thunderstorms were concentrated around Otis’s core on Tuesday, and expanding outflow at upper levels was evident on satellite, signs of a healthy tropical cyclone. Otis is embedded in a moist environment (mid-level relative humidity around 70 percent), with only moderate wind shear of 5-15 knots. The storm has a shot at rapid intensification on Tuesday as it moves over unusually warm waters of around 30 degrees Celsius (86 degrees Fahrenheit). The 12Z Tuesday SHIPS Rapid Intensification Index gave a 41% chance that Otis’s top sustained winds would reach 85 knots (100 mph) by Wednesday morning, which would make it a Category 2 storm.

Landfall is predicted around midday Wednesday just west of Acapulco, which would put the city in the stronger right-hand side of Otis. Flash flooding and mudslides will be a threat as widespread rains of 5-10 inches, and localized totals in the 10-20 inch range, drench Guerrero and western Oaxaca states near the coast and just inland.

Otis the sixth named Pacific storm to affect Mexico in 2023

Mexico’s Pacific coast has taken a beating from named storms in October, with Otis being the fourth storm to hit this month. If Otis arrives as a hurricane, it will be the third in less than three weeks to make landfall, compared to the long-term average of about 1.3 landfalling hurricanes on Mexico’s Pacific Coast for an entire season. The tally so far in 2023:

  • Hurricane Norma made landfall along the southern tip of the Baja California peninsula just west-northwest of Cabo San Lucas on October 21, with estimated maximum winds of 80 mph. After crossing the Gulf of California and weakening, Norma made a second landfall as a tropical depression on October 23 in the state of Sinaloa, roughly midway between Los Mochis and Mazatlan.
  • Hurricane Lidia made landfall on October 10 as a Category 4 storm with top sustained winds of 140 mph and a central pressure of 942 mb. This makes Lidia tied as the third-strongest landfalling Pacific hurricane on record for Mexico. Lidia hit the coast about 35 miles south-southwest of Puerto Vallarta. Lidia is being blamed for two deaths in Mexico.
  • Tropical Storm Max made landfall October 9 just to the west of Puerto Vicente Guerrero in the Mexican Provence of Guerrero with sustained winds of 65 mph and a central pressure of 991 mb. Max’s torrential rains brought significant flash flooding near the landfall region and to the southeast, in Acapulco. Max is being blamed for two deaths in Mexico.
  • Tropical Storm Hilary made landfall on August 20 in San Quintín, Baja California about 215 miles south-southeast of San Diego, California, with sustained winds of 65 mph. Hilary is being blamed for two deaths in Mexico.

In addition, the center of Hurricane Beatriz passed within five miles of the Mexican coast near Manzanillo on July 1. In 2022, five Pacific named storms made landfall in Mexico, including three hurricanes.

Tropical Cyclone Tej brings dangerous rains to Yemen and Oman

Tropical Cyclone Tej made landfall near Al Ghaydah, Yemen, close to the Oman border, on Monday afternoon as a Category 1 storm with 80 mph winds, according to the 2 p.m. EDT Monday advisories from the Joint Typhoon Warning Center and the India Meteorology Department (IMD). A storm surge of up to two meters (6.6 feet) was predicted near and to the right of the landfall location, according to IMD. Unfortunately, steering currents for Tej weakened significantly at the time of landfall, resulting in a very slow motion for the cyclone and subjecting the landfall region to an extended period of torrential rains.

Yemen TV reported that flooding from Tej killed at least seven people, and Al-Ghaydah Airport reported 406 mm (15.98 inches) of rain from Tej. The city of Rakhyut in Oman, located about 70 miles east of Tej’s landfall location, reported 245 mm (9.65 inches) of rain. This desert region normally receives only about 2-5 inches of annual rainfall, and flooding from Tej caused significant destruction.

Tej reached peak intensity as a high-end Category 3 storm with 125 mph winds at 18 UTC, October 22, according to the Joint Typhoon Warning Center. This makes Tej tied for seventh-strongest tropical cyclone on record in the Northern Indian Ocean’s Arabian Sea.

Tropical Cyclone Hamoon batters Bangladesh

Tropical Cyclone Hamoon (formerly called Tropical Cyclone 06B) formed on Monday morning in the North Indian Ocean’s Bay of Bengal, and peaked as a Category 1 storm with 90 mph winds at 2 a.m. EDT (6Z) Tuesday, according to the Joint Typhoon Warning Center. At 12Z (8 a.m. EDT) Tuesday, Hamoon was located 110 miles south-southwest of Chittagong, headed east-northeast at 9 mph with top sustained winds of 85 mph. Satellite images early Tuesday afternoon showed that Hamoon was bringing heavy rains to the coasts of Bangladesh and Myanmar, and was close to landfall.

The Joint Typhoon Warning Center predicted that high wind shear of 30 knots would rapidly weaken Hamoon, with landfall occurring later today in Bangladesh, near Cox’s Bazar. At landfall, JTWC predicted Hamoon would be a borderline tropical storm/Category 1 hurricane, with winds of 70-75 mph. The India Meteorology Department predicted that Hamoon would bring a storm surge of 1-1.5 meters to the coast.

A big concern for Hamoon’s landfall location is the tens of thousands of Rohingya refugees housed in camps in Bangladesh near the Myanmar border: the Kutupalong-Balukhali camp (population 635,000) and the Nayapara camp (population 23,000).

Hamoon will be the second tropical cyclone to hit this region in 2023. On May 14, Tropical Cyclone Mocha made landfall as a Category 4 storm with 155 mph winds in Myanmar, about 100 miles to the south of where Hamoon will make landfall. Mocha tied as the second-strongest cyclone at landfall in the North Indian Ocean in the JTWC database, and was the strongest storm ever observed in the North Indian Ocean when it was at its peak: a 175-mph Cat 5. Mocha killed 463 people and caused over $2.2 billion in damage, according to Gallagher Re.

Cyclone Lola lashes Vanuatu in the southeastern Pacific

In the southeastern Pacific, Tropical Cyclone Lola peaked as a Category 4 storm with 145 mph winds on Tuesday morning, according to the Joint Typhoon Warning Center. This makes Lola the strongest tropical cyclone ever observed in the Southern Hemisphere so early in their season, which runs from November through April. The previous earliest appearance of a cyclone with 145 mph winds in the Southern Hemisphere was on November 7, 1996, for Tropical Cyclone Bellamine.

Increasing wind shear reduced Lola’s intensity on Tuesday as the storm turned southwest toward Vanuatu, and at 8 a.m. EDT Tuesday, the Joint Typhoon Warning Center rated Lola a Category 3 storm with 125 mph winds. Lola is expected to continue on a southwesterly track through the Vanuatu archipelago through Wednesday and continue weakening, because of high wind shear at mid-levels of the atmosphere along with dry air aloft. The JTWC predicts that Lola will weaken to a Category 2 storm with 110 mph winds by the time it moves away from Vanuatu later on Tuesday.

Tropical Depression 21 brings heavy rains to Nicaragua and Honduras

Short-lived Tropical Depression 21 formed on Monday afternoon in the waters near the Atlantic coast of Nicaragua, and moved inland over Nicaragua early Tuesday morning. TD 21 dissipated late Tuesday morning. The remnants of TD 21 are expected to bring rains of four to eight inches to portions of Nicaragua over the next two days, which will be capable of causing dangerous flooding and mudslides. TD 21’s remnants may go on to help spawn the next eastern Pacific storm for Mexico:  Recent runs of the GFS and European model show the potential for a tropical cyclone to form by this weekend or early next week in the Pacific waters south of the Guatemala/Mexico border. In their 8 a.m. EDT Tuesday Tropical Weather Outlook, NHC gave this future system 2-day and 7-day odds of development of 0% and 20%, respectively.

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