Irma: A look at the dangers faced by various locations
By JASON SAMENOW, GREG PORTER | The Washington Post | Published: September 10, 2017
(Updated at 11:30 p.m. EDT)
Extremely dangerous Hurricane Irma first crashed into the Florida Keys on Sunday morning and then made a second landfall on Marco Island on Florida's west coast Sunday afternoon, unleashing violent wind gusts up to 142 mph and storm-surge flooding. The storm was plowing up Florida's west coast Sunday night and, once it's over, forecasters feared that this storm will go down as one of the worst in the state's history.
At 11 p.m., the storm was centered 50 miles southeast of Tampa. Its eyewall - containing the storm's most violent winds - had passed northeast of Sarasota. The storm center was plowing north at 14 mph into the area between Tampa and Orlando. Through around 2 a.m. Monday, wind gusts of 75 to 100 mph were possible in both cities, where winds had already gusted that high.
Hurricane-force wind gusts were also quite possible on the east coast of central Florida into early Monday, the Hurricane Center said, thanks to Irma's large wind field.
Around Tampa, once the storm center passes early Monday morning, a storm surge is possible of several feet above normally dry land, potentially inundating low-lying coastal areas.
Irma's peak winds of 100 mph, with higher gusts, had dropped 30 mph from the morning, making it a Category 2 hurricane (down from a Category 4). Even with slow weakening likely to continue as the storm passes over land, Irma remains very serious and life-threatening. The National Hurricane Center said it is expected to remain a hurricane through Monday morning.
Coastal waters could rise well above normally dry land along Florida's central Gulf Coast, inundating homes, businesses and roads.
Because of the storm's magnitude, the entire state of Florida is being severely affected by damaging winds, torrential rains and, in many areas, the risk of tornadoes. Tropical storm and hurricane conditions were also predicted to spread into the Florida Panhandle, eastern Alabama, much of Georgia and southern South Carolina by Monday.
Irma's eyewall passed on the east side of Sarasota around 10 p.m. and should pass between Tampa and Orlando through around 1 or 2 a.m., from south to north, producing wind gusts between 75 and 100 mph throughout the region. Both cities had already clocked gusts to near 80 mph.
Once Irma's center passes north of Tampa early Monday morning, the seas will rise likely resulting in areas of coastal inundation.
Even on Central Florida's east coast, tropical-storm force winds and hurricane-force gusts were fairly widespread Sunday evening. At St. Lucie, a gust reached 99 mph and Cape Canaveral gusted to 79 mph.
The worst winds had passed this region just prior to 9:30 p.m. but gusty showers continued on the storm's backside.
Irma's eyewall passed through Fort Myers and Cape Coral just before 7 p.m., producing wind gusts of 88 and 101 mph and then passed on the west side of Port Charlotte between 8 and 9 p.m.
As the eyewall moved over Naples late Sunday afternoon, it reported sustained winds of 93 mph and a gust to 142 mph - the strongest recorded from this storm in the U.S.
Josh Morgerman, a hurricane chaser positioned in Naples, described the scene: "Went thru violent, destructive winds. Screaming, whiteout, wreckage blowing by in fog." Then the calm eye moved overhead.
Before the arrival of the storm center, water was actually retreating from Naples to Tampa due to offshore winds from the east pulling the sea back. But forecasters warned residents that shortly after the storm's center passed to the north and winds blew back onshore, waters would rush back in rapidly causing severe inundation.
In Naples, as of 7 p.m., water levels were about four feet above normally dry land but was the level was starting to stabilize around 8 p.m.
In Ft. Myers, waters levels were rising through 10 p.m., but not as dramatically as they had in Naples.
In Southeast Florida, spiral bands continued to unleash tropical-storm-force winds. Even into the evening, winds were gusting up to 60 to 75 mph around Miami and West Palm Beach (7 p.m. gust of 75 mph), but they weren't as strong as earlier.
In the afternoon, sustained winds in Miami and Fort Lauderdale reached 50-60 mph through the early afternoon, gusting as high as 80 to 100 mph. Miami International Airport clocked a gust to 94 mph and an isolated gust hit 100 mph at the University of Miami.
Also during the afternoon the seas had risen several feet above normally dry land. Social media photos and videos showed water pouring through Miami's streets, in between high-rises, amid sideways sheets of rains.
Late Sunday afternoon, waters were finally starting to slowly recede around Miami.
While the core of the storm and worst winds passed the Keys early Sunday morning, the Weather Service warned storm surge flooding was ongoing as winds on the storm's backside shoved water over the islands. Gusts still reached 60 to 75 mph as of 6:40 p.m.
Early Sunday afternoon, the maximum surge at Cudjoe Key was estimated at 10 feet.
Over 2.5 million customers were without power.
Particularly in South and Central Florida, torrential rain was falling, with widespread totals of 6 to 10 inches and pockets up to 10 to 14 inches.
As the storm's spiral bands walloped Central and Northern Florida, the potential for tornadoes arose in the swirling air, and the Weather Service issued watches and scores of warnings.
Storm warnings in effect and predicted surge height and winds
Hurricane warnings cover all of Florida except the western Panhandle, where a tropical storm warning was in effect.
A storm-surge warning was also issued for much of the Florida Peninsula (except for a small section from North Miami Beach to Jupiter Inlet), and even extended up the Georgia coast into southern South Carolina. The Hurricane Center said that this would bring the risk of "dangerous" and "life-threatening" inundation and that the threat was highest along Florida's southwest coast and in the Florida Keys, where it said the surge is expected to be "catastrophic."
"In SOUTHWEST FLORIDA - the NAPLES-FT. MYERS-CAPE CORAL area, the potential exists for the worst hurricane in history," Norcross said.
Because of the shift in the most likely storm track to the west, Miami and Southeast Florida were most likely to miss the storm's intensely destructive core, known as the eyewall, where winds are strongest. Even so, because of Irma's enormous size, the entire Florida Peninsula and even the Panhandle were likely to witness damaging winds. The National Hurricane Center warned that the storm would bring "life-threatening wind impacts to much of the state."
Effects on Florida
Conditions will continue to deteriorate Sunday night over Florida in the central and north part of the state as Irma chugs up the coast. Conditions will slowly improve to the south.
During the evening, Port Charlotte, Sarasota and Tampa would face the storm's brunt.
Here's a guide to what is most likely and where . . .
Key West/Key Largo
Time frame for worst conditions: Through Sunday afternoon.
Hazard threats: Wind, storm surge and rain.
Wind gusts of up to 50 to 70 mph should continue into the evening.
A catastrophic storm surge of 5 to 10 feet or more is expected to inundate much of the island chain. Heavy rain will add to the water issues, as anywhere from 5 to 10 inches of additional rain will fall before the worst of the storm is over. Unfortunately, the damage potential on the Keys could be landscape-altering after taking a direct hit from this storm.
Miami/Fort Lauderdale/West Palm Beach
Time frame for worst conditions: Through Sunday night.
Hazard threats: Strong winds, tornadoes, heavy rain.
Sustained winds of 45 to 70 mph with gusts of 80-plus mph will last well into Sunday afternoon.
Swirling winds at all levels of the atmosphere have also increased the chances of tornadoes developing at any point on Sunday, especially in locations right along the water. Rainfall totals of four to eight inches or more are expected on Sunday alone, which may exacerbate localized flooding. With Irma's last-minute track shift to the west, the storm surge won't be as big of a concern here as it is elsewhere, with a two- to four-foot surge expected along much of Florida's east coast.
Naples/Fort Myers/Tampa Bay/St. Petersburg
Time frame for worst conditions: Through Monday morning.
Hazard threats: Storm surge and wind.
Irma's ultimate destination will be along the west coast of Florida. This means the conditions will deteriorate rapidly from Naples to Tampa Bay throughout Sunday afternoon. However, Irma's path will take it parallel to the west coast of Florida, keeping the entire region engulfed in the dangerous northeast quadrant of the storm, where winds are strongest. Sustained hurricane force winds and gusts over 100 mph should arrive in Naples Sunday afternoon and in St. Petersburg/Tampa Bay into the evening.
The most dangerous hazard for this region will be the extreme storm surge. Nowhere in the entire state will the storm-surge levels be higher than along the gulf-facing coast, with storm surge totals of eight to 12 feet and locally up to 15 feet forecast. Any coastal city from Tampa Bay south to Naples is at risk, with historic flooding (the likes of which haven't been seen in this area since Hurricane Donna in 1960) threatening thousands of people and structures.
Exceptional storm surge flooding possible in Naples & south including Marco Island
Time frame for worst conditions: Sunday night through Monday morning.
Hazard threats: Wind, rain, and tornadoes.
Inland areas won't escape the effects of Irma. The storm is extremely large in size, with tropical-storm-force winds extending outward over 200 miles from the center. The wind speeds in central Florida and the Orlando area will start to pick up by late Sunday afternoon, with sustained winds of 40 to 60 mph and gusts of 70-plus mph lasting from late Sunday night through Monday morning.
Heavy rain will also cause problems, with a general six to 12-plus inches of rain expected by the time the storm is over. The threat of tornadoes will increase by Sunday night, as well, as the storm's center tracks north along the west coast of Florida.
Time frame for worst conditions: Sunday evening through Monday afternoon.
Hazard threats: Rain, tornadoes, wind.
The northeast portion of Florida will be spared the worst of Irma but won't escape unscathed. Sustained tropical-force winds of 40 to 55 mph will overspread the area from Daytona Beach to Jacksonville by Sunday evening, with the worst winds (gusts up to 70 mph) occurring overnight. Heavy rain will be a story line here as six to 10-plus inches of rain is expected to fall in a relatively short period.
As with other parts of the state, the tornado threat will peak overnight on Sunday as Irma's storm center tracks northward.
Storm-surge values will be elevated (two to four feet) but should result in only minor to moderate coastal flooding.
Potential effects on Georgia and the southeastern U.S.
Time frame for worst conditions: Monday morning through Tuesday morning.
Hazard threats: Wind, rain and, at the coast, storm surge
Hurricane warnings extend well into Georgia, covering over half of the state. Parts of southern South Carolina also are under a hurricane warning, with Irma poised to maintain its hurricane-force strength for several hours after landfall.
Sustained tropical force winds of 25 to 45 mph will spread over Georgia from south to north starting late Sunday night. The strongest sustained winds (40 to 50 mph) with gusts of 60-plus mph will move in on early Monday morning, lasting through Monday evening. This includes Atlanta, which is under a tropical-storm warning, where sustained winds of 25 to 40 mph with gusts up to 60 mph will occur from about 10 p.m. Sunday night to about 5 p.m. Monday afternoon. This could lead to downed trees and outages.
Heavy rain is also expected, with storm totals of six to 10 inches forecast, the bulk of which should fall Monday.
Storm surge along the Georgia/South Carolina coast will be a hazard, as well, with the Hurricane Center predicting a surge of four to six feet. Of particular concern is the duration of the storm surge. Persistent onshore winds will extend the surge component here, with elevated water levels potentially lasting up to 36 hours.
Irma's path so far
On Sunday, the storm officially made landfall at Cudjoe Key at 9:10 a.m. as a Category 4 hurricane. Winds over the Keys raged, gusting to at least 94 mph in Key West (before the wind instrument failed) and up to 120 mph in Big Pine Key. Witness video showed the rising storm surge flooding Key West streets.
Before its encounter with the Keys, Irma made landfall on the north coast of Cuba as a Category 5 hurricane just after 9 p.m. Friday, with maximum sustained winds of 160 mph. It became that country's first Category 5 hurricane since 1924. Fueled by the extremely warm ocean temperatures, Irma reintensified to the maximum hurricane classification level after weakening slightly on Friday afternoon.
As it scraped Cuba's north coast early Saturday, it produced a sustained wind gust of 118 mph, and a gust to 159 mph was reported at Falla, Cuba, in the eyewall of the hurricane.
On Friday, before making landfall along Cuba's north-central coast, Irma passed north of Haiti and then between Cuba's northeast coast and the Central Bahamas.
Thursday evening, the center of the storm passed very close to the Turks and Caicos, producing potentially catastrophic Category 5 winds. The storm surge was of particular concern, as the water had the potential to rise 16 to 20 feet above normally dry land in coastal sections north of the storm center, causing extreme inundation.
A devastating storm surge and destructive winds had also probably battered the southeastern Bahamas, near Great Inagua Island.
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 people were reported to be without power. In Culebra, Puerto Rico, a small island 17 miles east of the main island, a wind gust registered 111 mph in the afternoon.
On Wednesday afternoon, the storm's eye had moved over Virgin Gorda in the British Virgin Islands, and its southern eyewall 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.
On Tuesday night and Wednesday morning, the hurricane passed directly over Barbuda and St. Martin in the northern Leeward Islands, the strongest hurricane 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.
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 maintained maximum wind speeds of at least 180 mph for 37 hours, longer than any storm on Earth on record, passing Super Typhoon Haiyan, the previous record-holder (24 hours).
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.
Irma's landfall pressure of 929 millibars in the Florida Keys was the lowest for any U.S. landfalling hurricane since Katrina (920 millibars) and for a Florida landfall since Andrew (922 millibars). It ranks as the seventh-lowest pressure of any U.S. landfalling storm.
Capital Weather Gang hurricane expert Brian McNoldy contributed to this report. Credit to tropical-weather expert and occasional Capital Weather Gang contributor Phil Klotzbach for some of the statistics in this section.