Tammy hits Lesser Antilles while Norma closes in on Cabo San Lucas

Hurricane season doesn’t end until Nov. 30, and the oceans are still cranking out storms. A pair of hurricanes in the Atlantic and Pacific — Tammy and Norma — are expected to impact land this weekend.

Tammy became a hurricane on Friday morning, and warnings have been hoisted for the bulk of the northern Leeward Islands, which bound the Atlantic and Caribbean Sea. The storm is expected to strengthen some, and could sideswipe the British Virgin Islands. By Sunday, eastern Puerto Rico could feel the effects of its outer rain bands, which may produce isolated flash flooding or a sporadic mudslide or two.

Hurricane Norma, meanwhile, was set to ram the southern Baja Peninsula on Saturday, potentially making a direct hit on Cabo San Lucas midday with what the National Hurricane Center is describing as “life-threatening hurricane conditions and a dangerous storm surge.”

Norma previously attained Category 4 intensity after a bout of rapid intensification between Wednesday and Thursday but had weakened to a Category 2 on Saturday.

There are also additional areas to watch in both ocean basins, including one in the Pacific that appears primed to become yet another named storm.

Hurricane Tammy is bringing hurricane and tropical storm conditions to the Leeward and northern Windward Islands, which will continue through Sunday. Wind gusts over 70 mph are likely for islands nearer to the storm’s center — particularly Guadeloupe, Antigua and Barbuda.

Parts of the Lesser Antilles could see up to a foot of rainfall as well; a general 2 or 3 inches is likely for most of Puerto Rico, with a bit more for the U.S. and British Virgin Islands. Isolated flooding is possible, particularly in high terrain.

In areas where onshore winds pile water against the coastline, a 1 to 3 foot storm surge, or sudden rise in sea level, can’t be ruled out.

Latest position and intensity

On Saturday, Hurricane Tammy was meandering through the Lesser Antilles. Its center was located about 50 miles east-southeast of Guadeloupe. Maximum sustained winds were around 85 mph, making Tammy a solid Category 1 hurricane. Some modest strengthening is possible.

Early on Saturday, the core of Tammy was passing just east of Dominica. That was visible on weather radars located on Martinique, Guadeloupe and Barbados. In addition to consolidating its inner core, Tammy also was able to generate a more pronounced eyewall. However, no clean eye has formed on satellite imagery. The hurricane was moving northwest at 9 mph.

Tammy is expected to largely maintain a semi-constant strength in the coming days. While water temperatures between 83 and 86 degrees would support strengthening, that’s being offset by a disruptive change of wind speed and/or direction with height known as wind shear.

Regarding Tammy’s track, it’s being steered between a clockwise-spinning zone of high pressure to the northeast, and a counterclockwise-spinning jet stream dip to the northwest. That will funnel the storm to the north-northwest, particularly as Tammy begins to feel the “scooping” effects of that jet stream dip.

Hurricane Norma is forecast by the National Hurricane Center to directly strike Cabo San Lucas as a Category 2 hurricane with 100 mph winds on Saturday.

In fact, the forecast track by the National Hurricane Center takes the storm just slightly to the northwest of the city. That’s even worse news, as it could place Cabo in the right eyewall of the storm, where onshore winds not only reach the strongest speeds of anywhere inside the storm, but also where the storm surge could be the highest, reaching 3 to 6 feet above normally dry land.

Norma could drop 10 to 15 inches of rainfall, which will cause freshwater flooding too.

On Saturday morning, Norma’s center was 20 miles offshore of Cabo San Lucas, where conditions were deteriorating. The city’s airport had already clocked wind gusts to 72 mph.

After a crescendo at Category 4 strength on Thursday, the storm was gradually weakening. Still, it’s likely to be a formidable storm as it lashes Cabo San Lucas.

After striking Cabo, Norma will work inland over Sinaloa, Mexico, bringing heavy rain and strong to locally damaging winds as the system slowly weakens early next week.

Some of its moisture will get drawn into Texas and the Mississippi River Valley next week, offering beneficial rains.

In the Atlantic, a weak disturbance over the Bay of Campeche has a minimal (20 percent) likelihood of developing, but it could still bring unsettled weather in the form of heavy downpours over Veracruz and Tabasco, Mexico.

In the eastern Pacific, meanwhile, strong winds funneling through the Tehuantepec Gap in Oaxaca, Mexico have allowed a little curl of vorticity, or spin, to form. That will likely result in a new named storm forming early next week in the Pacific Ocean west of Central America.

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