Intensifying Idalia barrels toward Florida as formidable hurricane

AccuWeather forecasters are urging those in the path of strengthening Hurricane Idalia to take the storm seriously as it barrels northward toward Florida. Idalia has been rated a 4 on AccuWeather's RealImpact™ Scale for Hurricanes in Florida due to anticipated life-threatening storm surge, damaging winds, and flooding rainfall.

Idalia became a hurricane Tuesday morning, and strengthening persisted throughout the day. Maximum sustained winds increased to 100 mph -- Category 2 force -- as of the late afternoon on Tuesday, according to the National Hurricane Center (NHC). The mid-evening update continued to show strengthening with winds of 105 mph. By the overnight hours, Idalia's winds reached 130 mph, making it a Category 4 storm, which is considered a major hurricane. AccuWeather meteorologists now expect Idalia to maintain Category 4 status, with winds greater than 130 mph, through landfall, which is expected to occur in the Big Bend area of Florida's west coast on Wednesday morning.

Officials issued mandatory evacuation orders in advance of the storm, and the National Guard is on call among other search and rescue groups that are ready to respond.

"The No. 1 killer in all of these storms is water, whether it's the storm surge that's going to happen at the coast or the excessive rainfall that might happen inland that causes urban flash flooding," FEMA Administrator Deanne Criswell told CNN on Tuesday.

Hurricane Idalia as seen over the eastern Gulf of Mexico on Tuesday afternoon, Aug. 29, 2023. (AccuWeather Enhanced RealVue™ satellite)

Hurricane and storm surge warnings are in effect for the west coast of Florida, including Tampa Bay. Tropical storm watches and warnings are also out for other regions of Florida's Gulf Coast, including the Florida Keys, as well as the central and northern portion of the Florida Atlantic Coast, all the way to the central coast of South Carolina.

Idalia's dangers will not be confined to Florida, as impacts will be felt by millions across the southeastern United States from Georgia to the Carolinas and Virginia.

Hurricane Idalia began picking up steam and started to move northward over the Gulf of Mexico Tuesday morning after a slow, erratic path near western Cuba Monday.

"AccuWeather meteorologists are concerned that this system could strengthen rapidly up until the point of landfall as it moves across an area of very high ocean temperatures in the Gulf," AccuWeather Meteorologist Brandon Buckingham said. Rapid intensification of a tropical cyclone is defined as an increase in maximum sustained winds of at least 35 mph (55 km/h) in a period of 24 hours or less, according to the NHC.

"Damaging winds of 40 to 60 mph can occur across most of Florida and parts of the Southeast," said Buckingham. From just north of Tampa to the Georgia coastline, wind gusts north of 80 mph are expected. "Closest to where the tropical system makes landfall, wind gusts of up to 120 to 140 mph can occur." Widespread power outages are likely with the potential for the power to be out for an extended period of time due to extensive tree damage.

Given the risk for continued rapid intensification, an AccuWeather Local StormMax™ of 165 mph is possible near landfall near the panhandle and Big Bend of Florida. At that strength, powerful gusts of a Category 5 hurricane are possible. AccuWeather hurricane experts are forecasting Idalia to come ashore as a major hurricane, with Category 4 level sustained winds ranging from 130-156 mph on the Saffir-Simpson Hurricane Wind Scale.

Storm surge is also a major concern as the intensifying tropical system nears the Gulf Coast of Florida. The winds surrounding Idalia will push water into the eastern- and southern-facing beaches for several days, allowing water to build up over time.

A storm surge of at least 3-6 feet is likely from Ochlockonee Bay, Florida, in the eastern panhandle, to Port Charlotte. The most significant storm surge, perhaps as high as 15 feet, is expected near and just to the southeast of Idalia's landfall. At this time, a high-level storm surge of 10-15 feet is most likely to occur from Steinhatchee to Homosassa, Florida. It's not out of the question that some portions of Tampa Bay could have a storm surge of 7 or 8 feet, according to AccuWeather Lead Hurricane Expert Dan Kottlowski.

Even a storm surge of a few feet can create life-threatening conditions, due to the force of the rapidly rising water. The worst effects from storm surge are likely as the center passes to the north of locations along the west coast of the peninsula, and winds flip around to the west, pushing Gulf of Mexico water inland.

The combination of onshore winds, the effects of the full moon and powerful Hurricane Franklin at sea will bring a storm surge on the opposite coast from where Idalia makes landfall. A storm surge inundation of up to 3-6 feet is likely from near Jacksonville, Florida, to Charleston, South Carolina.

At the same time, AccuWeather meteorologists are warning that a swath of 4 to 8 inches of rainfall is possible from northern Florida through the Southeast, and that it will bring a widespread risk of flooding.

Where the most intense rainfall occurs, rainfall totals can approach an AccuWeather Local StormMax™ of 18 inches, which would lead to major, life-threatening flooding, since most of the rain will fall over the span of 12 hours or less. Low-lying area flooding can occur quickly, followed by progressively larger stream and river flooding in the hours and days ahead.

"Tornadoes can also occur to the east of the center of the circulation as it moves across Florida," AccuWeather Senior Meteorologist Dan Pydynowski added.

A few tornadoes and/or waterspouts are possible along the west-central and southwestern part of the Florida Peninsula and Keys through Wednesday. The greatest risk of multiple tornadoes will be through Wednesday night over the northern and central part of the Florida Peninsula to southeastern Georgia. The risk of tornadoes on Thursday will shift to the zone from northeastern Florida to the near-coastal Carolinas.

Panama City, Mexico Beach, Apalachicola, Steinhatchee and Cedar Key are among the locations along or near the Gulf Coast in or near the higher risk area.

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AccuWeather meteorologists warn that significant impacts from the storm will also occur outside of the cone. Because of this, all residents and tourists, not just near the storm's forecast eye path, should monitor its progress.

Despite an expected gradual loss of wind intensity after the storm comes ashore, the threats will not be limited to just the Gulf Coast and the Sunshine State. A large swath of the Southeast will be at risk for flooding, damaging winds and coastal impacts, especially as the system interacts with a frontal boundary that is stalled over the region.

Rain totaling 4 to 8 inches and wind gusts of at least 40 mph can occur all the way through eastern Georgia and the Carolinas through late week, complicating vacation plans for some in the days leading up to the Labor Day weekend. AccuWeather forecasters say that rainfall amounts can range between 8 to 12 inches along a narrow corridor in north-central Florida.

Those looking to head to the beaches along Florida's Gulf coast, and even along the southeastern Atlantic coast, will have to be wary of rough surf and rip currents, which have begun ahead of the storm's arrival. This increase in wave activity along the East Coast will not only be due to Idalia but also from Hurricane Franklin, which is churning well off in the Atlantic as of Tuesday.

"By late week, the storm can turn toward the east and reemerge over the Atlantic Ocean," added Buckingham. At this point, little reintensification can be expected.

There is some data suggesting that Idalia could enter a zone with weak steering breezes not long after reaching the Atlantic. If so, it is possible that the system could loop around and head back toward the U.S., and perhaps Florida.

Idalia was the 10th tropical or subtropical storm to form during the 2023 Atlantic hurricane season. According to a post on X from Colorado State University hurricane expert Philip Klotzbach, this season is just the seventh since modern records began in which 10 storms had formed by Aug. 27.

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