Both storms could generate “life-threatening” swells and rip currents, the Hurricane Center added.
Norma rapidly intensifies
Norma’s maximum sustained winds nearly doubled between early Wednesday morning and early Thursday morning, jumping from 65 mph to 120 mph in just 24 hours. The storm joins a growing number of tropical systems that have met the criteria for rapid intensification in recent years, which is defined as a storm that undergoes a 24-hour wind increase of at least 35 mph.
As of 11 a.m. Thursday, Norma’s peak winds were up to 130 mph; the storm was centered about 245 miles southwest of Manzanilla, Mexico, and about 410 miles south of Cabo San Lucas. Norma was forecast to remain near its current intensity on Thursday before starting to weaken by early Friday.
Norma was forecast to track northward during the next few days and still be near hurricane strength upon reaching the southern tip of Baja California this weekend, possibly making landfall near Cabo San Lucas. There was some disagreement among models whether Norma will stall just southwest of Baja California, slam into it head-on, or sideswipe it to the east. A hurricane watch was in effect for Baja California from Todos Santos to Los Barriles.
“Heavy rainfall from Norma will begin to impact the far southern portions of Baja California Sur late Friday, continuing through Sunday,” the Hurricane Center said. “This rainfall may produce flash and urban flooding, along with possible mudslides in areas of high terrain.”
General rainfall amounts of 5 to 10 inches were predicted across the far southern portion of Baja California Sur, with localized amounts up to 15 inches. Swells generated by Norma were already impacting the coast of southwestern Mexico and were forecast to spread north along the western Mexican coast and toward Baja California. “These swells are likely to cause life-threatening surf and rip current conditions,” the Hurricane Center added.
Moisture from Norma could eventually enhance rainfall next week in the Southern Plains, where some areas are experiencing extreme to exceptional drought, according to the latest U.S. Drought Monitor.
Moisture from what is currently Tropical Storm Norma in the eastern Pacific may feed into a low pressure system and spread rain to the southern Plains next week, but with uncertainty in amounts. Here’s our latest precip forecast for Days 6-7 (Mon evening-Wed evening). pic.twitter.com/w5ZYczfOrH
— NWS Weather Prediction Center (@NWSWPC) October 18, 2023
To the southeast of Norma, another disturbance was showing signs of development. That system, several hundred miles south of the Gulf of Tehuantepec, now has an 80 percent chance of becoming a tropical storm in the next week and a 50 percent chance in the next two days. It’s too soon to say whether it would become a threat to land.
Tammy could become a hurricane
Tropical Storm Tammy was about 425 miles to the southeast of Guadeloupe on Thursday morning with maximum sustained winds of 60 mph. Tammy was forecast to gradually strengthen to a Category 1 hurricane with winds of 75 to 85 mph by this weekend as it tracks to the west and then northwest.
A tropical storm warning and hurricane watch were issued for Guadeloupe. Meanwhile, tropical storm watches were in effect for much of the northern Lesser Antilles, including Barbados, Dominica, Martinique, Antigua, Barbuda, Montserrat, St. Kitts, Nevis, Anguilla, St. Barthelemy, Saba, St. Eustatius and St. Martin, because of the potential for tropical storm conditions as soon as Friday. Puerto Rico and the Virgin Islands could see tropical-storm-force winds by Saturday.
A storm surge, or sudden rise in sea level, of up to a foot to 3 feet above normal tide could occur near where the center of Tammy crosses the Leeward Islands.
“Heavy rains from Tammy will begin to affect the northern Windward and Leeward Islands on Friday, spreading into the British and U.S. Virgin Islands and Puerto Rico over the weekend,” the Hurricane Center said. “This rainfall may produce isolated flash and urban flooding, along with isolated mudslides in areas of higher terrain.”
Tammy was predicted to produce 3 to 6 inches of rainfall, with localized amounts up to 10 inches, across portions of the Windward and Leeward Islands, while the Virgin Islands and eastern Puerto Rico could see 1 to 2 inches of rain with localized amounts up to 4 inches. Life-threatening swells and rip currents were possible for portions of the Lesser Antilles as soon as Thursday.
The Hurricane Center’s forecast shows Tammy moving north and northeastward into the open ocean early next week, unlikely to threaten the U.S. mainland. Tammy is the 20th named storm in the Atlantic this hurricane season, marking only the fourth year to record at least 20 named storms in the Atlantic by Oct. 18, according to Philip Klotzbach, a researcher on the Tropical Weather and Climate Research team at Colorado State University.