CNN –
Two hurricanes will make landfall in two different ocean basins this weekend – Tammy in the Atlantic and Norma in the eastern Pacific.
Neither poses a threat to the United States, but Norma has triggered hurricane warnings for Mexico, including the popular resort of Cabo San Lucas, and Tammy for parts of the Leeward Islands, a chain of several island nations between the Caribbean Sea and the open Atlantic.
Tammy was a Category 1 hurricane with sustained winds of 80 mph Friday evening and was centered about 55 miles east of Martinique, the National Hurricane Center said at 11 p.m. ET. It is forecast to slowly strengthen as it moves through the Leeward Islands.
Hurricane-force winds extended up to 25 miles from the center of the storm, and tropical-storm-force winds extended outward up to 125 miles.
Tammy was expected to move near or over parts of the Leeward Islands by Saturday night and then move north of the Northern Leeward Islands on Sunday.
Hurricanes are rare in this part of the Atlantic in late October. According to hurricane expert Michael Lowry, Tammy is only the third hurricane to form this far southeast in the Atlantic since 1900.
It is also the youngest hurricane to hit this part of the Atlantic since 1966, according to Phil Klotzbach, a scientist at Colorado State University’s Department of Atmospheric Science.
Hurricane experts previously warned that hurricanes could form in unusual areas later this year due to the exceptionally warm Atlantic Ocean.
A storm surge of 1 to 3 feet is possible for portions of the Leeward Islands.
Heavy rainfall is one of the storm’s greatest threats and can lead to flash floods and mudslides. Rainfall totals are expected to range from 4 to 8 inches in the Leeward Islands, but could reach 1 foot in places where the heaviest rain occurs. Rainfall should be less in Puerto Rico and the British and U.S. Virgin Islands, where 1 to 2 inches of rain is most likely.
Starting late Sunday, conditions will improve along the island chain from south to north as the storm moves northward from the region.
With Tammy in the Atlantic, only two names – Vince and Whitney – are now on the standard Atlantic storm name list before the hurricane center resorts to an alternative name list.
Hurricane Norma was a Category 3 storm with maximum sustained winds of 120 miles per hour in the Pacific Ocean as of 9 p.m. MT on Friday, the National Hurricane Center said. It was centered about 145 miles south of Cabo San Lucas, Mexico.
The storm is expected to weaken before making landfall on Saturday. However, it is still expected to be a hurricane when it moves near or over the southern part of Baja California Sur – including the Cabo San Lucas area – late Saturday afternoon or early Saturday evening.
And a dangerous storm surge “will likely result in coastal flooding in areas with onshore winds within the hurricane warning area,” the National Hurricane Center said.
“Near the coast, the surge will be accompanied by large and destructive waves,” the hurricane center said.
Tropical storm conditions were expected to develop into hurricane conditions by early Saturday in southern Baja California Sur, including Cabo San Lucas.
The storm will bring heavy rain and flooding to the region through Sunday. Through Sunday, rainfall totals of 5 to 10 inches are possible in the far south of California’s Baja Sur, with isolated amounts of up to 15 inches.
“This rainfall will likely result in flash flooding and urban flooding, along with possible mudslides in higher elevations,” the National Hurricane Center warned.
After touching Baja California Sur, the storm will then turn east, cross the Gulf of California and make landfall somewhere on the east coast of mainland Mexico early Monday.