Category 5 Irma stays on perilous path toward Florida

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In this GOES-16 geocolor image satellite image taken Thursday, Sept. 7, 2017, the eye of Hurricane Irma, center, is just north of the island of Hispaniola, with Hurricane Katia, left, in the Gulf of Mexico, and Hurricane Jose, right, in the Atlantic Ocean. Irma, a fearsome Category 5 storm, cut a path of devastation across the northern Caribbean, leaving at least 10 dead and thousands homeless after destroying buildings and uprooting trees on a track Thursday that could lead to a catastrophic strike on Florida. Irma pummels Caribbean, heads to Florida.In this geocolor image captured by GOES-16 and released by the National Oceanic and Atmospheric Administration (NOAA), Hurricane Irma approaches Anguilla on Wednesday, Sept. 6, 2017. The most powerful Atlantic Ocean hurricane in recorded history has roared into the Caribbean, its winds ripping off roofs and knocking out phones. It’s on a path toward Puerto Rico, the Dominican Republic, Haiti and Cuba before possibly hitting Florida.

Hurricane Irma, the massive, record-setting Category 5 hurricane, continues to track toward south Florida, where it could deliver a devastating blow. Before it hits Florida, it may well leave behind catastrophic damage in the Turks and Caicos and parts of the Bahamas. By early next week, South Carolina could well be in the storm’s crosshairs.

Meanwhile, two other hurricanes were intensifying in the eastern Atlantic and southwest Gulf of Mexico – Jose and Katia. On Saturday, Jose could hit some of the same small islands in the northern Lesser Antilles decimated by Irma, including Antigua and Barbuda.

But Irma is the most pressing concern. As the storm charged ever closer to the U.S. mainland, the National Hurricane Center issued hurricane watches Thursday morning for the Florida peninsula from Jupiter Inlet southward and around the peninsula to Bonita Beach, including the Florida Keys.

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A storm-surge watch was issued for the same area of Florida because of the potential for water to rise well above normally dry land at the coast as the storm approaches.

“The threat of dangerous major hurricane impacts in Florida continues to increase,” the Hurricane Center said Thursday morning.

Closer to the storm’s immediate location, hurricane warnings were in effect for the Dominican Republic, Haiti, the Turks and Caicos, and the Bahamas.

Early Tuesday afternoon, the storm chugging along at 16 mph toward the west-northwest between the north coast of the Dominican Republic and the Turks and Caicos, positioned about 70 miles southeast of Grand Turk. The Hurricane Center reported a weather station on Grand Turk reported a wind gust of 66 mph Thursday afternoon with the storm center still more than 70 miles away.

The storm, packing maximum sustained winds of 175 mph, has maintained Category-5 winds (157 mph+) for two days now. As it remains clear of large land masses, which would disrupt the storm, and passes over some of the warmest water in the world (nearly 90 degrees), significant weakening is unlikely. The National Hurricane Center predicts that Irma will remain a powerful Category 4 or 5 hurricane as it approaches Florida.

This historically extreme hurricane, which maintained winds of 185 mph longer than any storm ever recorded, will produce the full gamut of hurricane hazards across the Bahamas and potentially south Florida, including a devastating storm surge, destructive winds and dangerous flash flooding.

The Hurricane Center is urging residents of Florida to rush preparations to completion.

A out of order sign is placed over a gas pump at Marathon gas station on Wednesday, Sept. 6, 2017 in Sunny Isles Beach, Fla. Heavy rain and 185-mph winds lashed the Virgin Islands and Puerto Rico’s northeast coast Wednesday as Hurricane Irma roared through Caribbean islands on its way to a possible hit on South Florida.

Potential effects on Florida and the Southeast U.S.

In south Florida, this storm is being taken as deadly serious. Coastal areas are being evacuated, shelters are being established, and food and gas supplies have dwindled. Although there is uncertainty in the track and the exact path of the violent eye wall, where winds are the strongest, it will be difficult for the state to avoid a disaster: It’s just a matter of how severe.

Tropical-storm-force winds are expected to reach south Florida by Saturday as Irma approaches from the southwest. Then, the all-important northward turn is still expected to take place early Sunday, when the storm would make landfall. Exactly where the north turn occurs is the critical question for Florida.

As of Thursday morning, the most likely scenario based on computer-model guidance was that the storm will track along or just off the state’s east coast.

Models, however, can shift. The difference between a track just off the east coast and just off the west coast is only 150 miles, and the average error in hurricane forecasts this far in advance is about that big. It is still not out of the question that Irma could track north up the west coast of the Florida peninsula or directly up the spine.

If the storm tracks up Florida’s east coast, then Miami, Fort Lauderdale, West Palm Beach, Melbourne, Daytona Beach and Jacksonville will take big hits. If it runs up the spine of the peninsula, the storm will be quicker to decay but hurricane-force winds would reach both coasts. If it buzz-saws up the west coast, then Key West, Naples, Fort Myers, Tampa and Tallahassee would face devastating effects.

When Irma makes its closest approach to Florida – most likely early Sunday – the Hurricane Center predicts that it will produce Category 3 or 4 winds. Here is its description of the kind of damage Category 4 winds would inflict:

“Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.”

Note that such extreme winds are typically confined to the eye wall, which is only about 10 to 15 miles wide. That is why the exact track is important in terms of where the most severe wind damage concentrates.

Irrespective of exactly where Irma tracks, it appears inevitable that many coastal population centers in Florida will experience a devastating storm surge of 5 to 10 feet above normally dry land, inundating roads, homes and businesses. The biggest storm surge will occur immediately north of the storm center.

In southeast Florida, the Hurricane Center forecasts 8 to 12 inches of rain with isolated amounts to 20 inches.

Beyond Florida, there is a big risk for destructive winds and a serious storm surge up to Georgia, South Carolina and North Carolina, but the details greatly depend on the track over Florida.

The worst case for these states would be if Irma narrowly misses the east coast of Florida, stays over warm water and then hits them while maintaining its strength. A potential landfall along the Southeast coast would be Monday. Models project that South Carolina is the most likely landfall location, but that could change.

“The chance of direct impacts is increasing in portions of Georgia, South Carolina and North Carolina,” the Hurricane Center said Thursday morning.

As the storm tracks up the Southeast coast and then inland, heavy rain will expand over a large area, along with the potential for flash flooding, although it’s too soon to pinpoint what areas will receive the most rain.

A man covers a bodega’s windows before the arrival of Hurricane Irma in Las Terrenas, Dominican Republic, Wednesday, Sept. 6, 2017. Dominicans are getting ready for the arrival of Hurricane Irma after battering Puerto Rico with heavy rain and powerful winds, leaving more than 600,000 people without power as authorities struggle to get aid to small Caribbean islands already devastated by the historic storm.A man puts tape on a store’s glass doors before the arrival of Hurricane Irma in Las Terrenas, Dominican Republic, Wednesday, Sept. 6, 2017. Dominicans are getting ready for the arrival of Hurricane Irma after battering Puerto Rico with heavy rain and powerful winds, leaving more than 600,000 people without power as authorities struggle to get aid to small Caribbean islands already devastated by the historic storm.

Effects on the Hispaniola, Turks and Caicos, Bahamas

Before Irma threatens south Florida, it is predicted to first scrape along the north coast the Dominican Republic and Haiti. The center of the storm and its worst winds are predicted to remain offshore. However, these areas will be subject to damaging wind gusts and flash flooding.

Thursday afternoon and night, the center of the storm may pass directly over the Turks and Caicos, producing potentially catastrophic Category 5 winds and 8 to 12 inches (locally up to 20 inches) of rain. The storm surge is of particular concern, as the water may rise 16 to 20 feet above normally dry land in coastal sections north of the storm center, causing extreme inundation.

A devastating storm surge of 16 to 20 feet is also possible in the southeastern Bahamas on Thursday night into Friday, along with hurricane-force winds. The Hurricane Center also notes that much of the Bahamas could see to 8 to 12 inches of rain through Saturday.

A child plays in a puddle in the seaside slum of Port-au-Prince, Haiti, Wednesday, Sept. 6, 2017. Heavy rain and 185-mph winds lashed the Virgin Islands and Puerto Rico’s northeast coast Wednesday as Hurricane Irma roared through Caribbean islands. The northern parts of the Dominican Republic and Haiti could see 10 inches of rain. This Sept. 6, 2017 photo provided by the Dutch Defense Ministry shows a few of the homes that remained intact in the aftermath of Hurricane Irma, in St. Maarten. Irma cut a path of devastation across the northern Caribbean, leaving thousands homeless after destroying buildings and uprooting trees. Significant damage was reported on the island that is split between French and Dutch control.

Irma’s path so far

Through early Thursday, the storm had battered islands from Puerto Rico to the northern Lesser Antilles.

While the center of Irma passed just north of Puerto Rico late Wednesday, a wind gust of 63 mph was clocked in San Juan early Wednesday evening, and more than 900,000 were reported to be without power. In Culebra, Puerto Rico, a small island 17 miles east of the mainland, a wind gust registered 111 mph in the afternoon.

Wednesday afternoon, the storm’s eye had moved over Virgin Gorda in the British Virgin Islands, and its southern eye wall (the region of most powerful winds) raked St. Thomas in the U.S. Virgin Islands.

Early Wednesday afternoon, a wind gust to 131 mph was clocked on Buck Island and 87 mph on St. Thomas in the U.S. Virgin Islands.

Tuesday night and Wednesday morning, the hurricane passed directly over Barbuda and St. Martin in the northern Leeward Islands, the strongest hurricane ever recorded in that region and tied with the 1935 Florida Keys hurricane as the strongest Atlantic storm to strike land.

As Barbuda took a direct hit, the weather station there clocked a wind gust to 155 mph before it went offline.

The storm also passed directly over Anguilla and St. Martin early Wednesday, causing severe damage.

Families gather at a shelter in a local church during the evening before the arrival of Hurricane Irma in Las Terrenas, Dominican Republic, Wednesday, Sept. 6, 2017. Dominicans wait for the arrival of Hurricane Irma after it lashed Puerto Rico with heavy rain and powerful winds, leaving nearly 900,000 people without power as authorities struggled to get aid to small Caribbean islands already devastated by the historic storm.Rescue staff from the Municipal Emergency Management Agency investigate an empty flooded during the passage of Hurricane Irma through the northeastern part of the island in Fajardo, Puerto Rico, Wednesday, Sept. 6, 2017. Hurricane Irma lashed Puerto Rico with heavy rain and powerful winds, leaving nearly 900,000 people without power as authorities struggled to get aid to small Caribbean islands already devastated by the historic storm.Rescue staff from the Municipal Emergency Management Agency investigate an empty flooded during the passage of Hurricane Irma through the northeastern part of the island in Fajardo, Puerto Rico, Wednesday, Sept. 6, 2017. Hurricane Irma lashed Puerto Rico with heavy rain and powerful winds, leaving nearly 900,000 people without power as authorities struggled to get aid to small Caribbean islands already devastated by the historic storm.People make their own sandbags to protect in their homes before the arrival of Hurricane Irma in Las Terrenas, Dominican Republic, Wednesday, Sept. 6, 2017. Dominicans are getting ready for the arrival of Hurricane Irma after battering Puerto Rico with heavy rain and powerful winds, leaving more than 600,000 people without power as authorities struggle to get aid to small Caribbean islands already devastated by the historic storm.Joshua Alicea, right, rescue staff member from the Municipal Emergency Management Agency toured the streets of the Matelnillo community searching for citizens in distress during the passage of Hurricane Irma through the northeastern part of the island in Fajardo, Puerto Rico, Wednesday, Sept. 6, 2017. The US territory was first to declare a state of emergency las Monday, as the National Hurricane Center forecast that the storm would strike the Island Wednesday. High winds and rain sweep through the streets of the Matelnillo community during the passage of hurricane Irma, in Fajardo, Puerto Rico, Wednesday, Sept. 6, 2017. The US territory was first to declare a state of emergency las Monday, as the National Hurricane Center forecast that the storm would strike the Island Wednesday.A man surveys the wreckage on his property after the passing of Hurricane Irma, in St. John’s, Antigua and Barbuda, Wednesday, Sept. 6, 2017. Heavy rain and 185-mph winds lashed the Virgin Islands and Puerto Rico’s northeast coast as Irma, the strongest Atlantic Ocean hurricane ever measured, roared through Caribbean islands on its way to a possible hit on South Florida. An employee from an electrical company works to remove a tree felled by Hurricane Irma, in Sanchez, Dominican Republic, Thursday, Sept. 7, 2017. Irma cut a path of devastation across the northern Caribbean, leaving thousands homeless after destroying buildings and uprooting trees. Irma flooded parts of the Dominican Republic when it roared by, just off the northern coast of the island it shares with Haiti.

Irma’s place in history

Irma’s peak intensity (185 mph) ranks among the strongest in recorded history, exceeding the likes of Katrina, Andrew and Camille – whose winds peaked at 175 mph.

Among the most intense storms on record, it trails only Hurricane Allen in 1980, which had winds of 190 mph. It is tied for second-most intense with Hurricane Wilma in 2005, Hurricane Gilbert in 1988 and the 1935 Florida Keys hurricane.

The storm has maintained maximum wind speeds of at least 180 mph longer than any other storm on record in the Atlantic or Pacific Ocean.

Late Tuesday, its pressure dropped to 914 millibars (the lower the pressure, the stronger the storm), ranking as the lowest of any storm on record outside the Caribbean and Gulf of Mexico in the Atlantic basin.

The storm has generated the most “accumulated cyclone energy,” a measure of a storm’s duration and intensity, of any hurricane on record.

Without a doubt, the World Meteorological Organization will retire the names Harvey and Irma after this season. While there have been several instances of consecutive storm names getting retired (Rita and Stan 2005, Ivan and Jeanne 2004, Isabel and Juan 2003, Luis and Marilyn 1995), the United States has been hit by more than one Category 4+ hurricane in a season only one time: 1915. Two Category 4 hurricanes hit in Texas and Louisiana six weeks apart that year.

Credit to tropical-weather expert and occasional Post contributor Phil Klotzbach for some of the statistics in this section.

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