For more than a day, monstrous Hurricane Irma has sustained Category 5 winds, while ripping through the northern Lesser Antilles. The storm, tied for the second strongest ever recorded in the Atlantic Ocean, is charging toward the Virgin Islands, Puerto Rico, southeastern Bahamas and, by the weekend and early next week, Florida and the Southeast U.S.
This is a life-threatening storm that the National Hurricane Center warns is capable of catastrophic damage. Preparations should be rushed to completion near its path.
Packing peak winds of 185 miles per hour, the hurricane passed directly over Barbuda and Saint Martin in the northern Leeward Islands Tuesday night and Wednesday morning, 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 miles per hour before it went offline. The storm surge on the island, or the rise in water above normally dry land, reached at least 8 feet.
As the storm heads west, hurricane warnings are in effect for the Virgin Islands, Puerto Rico, the Dominican Republic, the Turks and Caicos, Haiti and southeastern Bahamas. A hurricane watch covers Cuba and the central Bahamas.
This historically intense hurricane is forecast to modestly weaken in the next two days, but remain an extremely dangerous Category 4 or 5 storm. It will produce the full gamut of hurricane hazards across the Caribbean and potentially South Florida, including a devastating storm surge, destructive winds and dangerous flash flooding.
Mainland U.S. landfall threat
Model forecasts have shifted the center of the track eastward since Tuesday – projecting the core of Irma to pass right along or just offshore Florida’s east coast. But enough uncertainty in the track exists such that the entirety of Florida should be on the highest alert and preparing for this hurricane.
Tropical-storm-force winds are likely to arrive in Florida on Saturday, with the worst storm conditions occurring on Sunday. The most extreme conditions are likely to occur near the storm center, but it is impossible this far out to pinpoint exactly where that will track.
The entire Florida peninsula is only about 100 miles wide, small compared to the size of the storm. Tropical-storm-force winds presently extend outward up to 185 miles from the storm center and hurricane-force winds 50 miles in both directions.
A hurricane does not need to be rated Category 5 intensity to cause catastrophic damage. Remember, the category rating only refers to the peak winds in the eyewall, not the size of the storm, the rainfall, and the storm surge.
Locations in northern Florida as well as up into Georgia and the Carolinas should also be preparing for a significant impact Monday and Tuesday.
The latest suite of models also shows an increasing threat of hurricane conditions to Georgia and the Carolinas early next week. In some respects, the most recent set of model runs bear some resemblance to Hurricane Matthew, which affected these areas just 11 months ago.
The rainfall forecast over the coming week shows a heavy swath over the Florida peninsula, and then spreading northward into the Carolinas as Irma likely tracks over those areas early next week.
Impact on the Leeward Islands, Virgin Islands and Puerto Rico
Irma presents a clear and present danger to the U.S. Virgin Islands and, in particular, the British Virgin Islands which the center may pass directly over Wednesday.
Areas affected by the core winds near the storm’s eye face devastating wind destruction. The Hurricane Center provides this description of the damage inflicted by Category 5 winds:
“A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.”
Forecasts also call for rainfall totals of 8-12 inches along the path, with isolated amounts up to 20 inches, leading to flash flooding and mudslides – especially over any high terrain.
After passing the Virgin Islands, the storm will approach Puerto Rico late Wednesday afternoon or evening. The center may pass just north of Puerto Rico or could pass over its northern section. Either way, destructive winds are likely there, especially over the northeast part of the island, along with 4 to 10 inches of rain (and isolated totals up to 15 inches) and a storm surge of 4 to 6 feet in coastal areas.
After passing Puerto Rico, the storm should then pass just north of the Dominican Republic and Haiti on Thursday, where hurricane-force winds and torrential rains are possible.
Later on Thursday, the storm will near the Turks and Caicos and and southeastern Bahamas, where it could push ashore a devastating storm surge of 15 to 20 feet above normally dry land.
Irma’s place in history
Irma’s peak intensity (185 miles per hour) so far 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 only trails Hurricane Allen in 1980 which had winds of 190 miles per hour. It is tied for second most intense with Hurricane Wilma in 2005, Hurricane Gilbert in 1988 and the 1935 Florida Keys hurricane.
Late Tuesday night 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 both 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 U.S. has only been hit by more than one Category 4+ hurricane in a season one time: 1915. Two Category 4 hurricanes hit in Texas and Louisiana six weeks apart that year.
Tropical storms Jose and Katia
While Irma is grabbing all of the attention, two other tropical storms are spinning in the Atlantic basin:
–Tropical Storm Jose, far out in the eastern Atlantic Ocean, is expected to strengthen into a hurricane Wednesday. The current track forecast keeps it mostly away from land areas over the next several days but it could graze the same islands in the northeastern Lesser Antilles slammed by Irma this weekend and forecasters will be watching it closely.
–Tropical Storm Katia, which formed early Wednesday in the southwestern Gulf of Mexico, is also forecast to become a hurricane – on Thursday or Friday, before making landfall in the Mexico state of Veracruz this weekend.
Hurricane season in perspective
In terms of Accumulated Cyclone Energy for all storms so far, 2017 has spiked to well above average in the past week thanks to Irma. And now we also have Tropical Storm Jose and Tropical Storm Katia adding to the tally. As of Wednesday morning, this season’s Accumulated Cyclone Energy is at about 152 percent of average for the date.
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