Irma becomes strongest Atlantic hurricane outside Gulf and Caribbean ever recorded

Irma spun into a monster storm Tuesday morning with sustained winds topping 180 mph, becoming the strongest Atlantic hurricane ever recorded outside the Gulf of Mexico and Caribbean, National Hurricane Center forecasters said in their 11 a.m. advisory.

As the hurricane churns closer to the U.S. coast, its path becomes more certain, with South Florida increasingly likely to take a hit. Tropical storm force winds could arrive as early as Friday. Gov. Rick Scott has declared a state of emergency for all 67 counties and will spend much of Tuesday morning in hurricane briefings.

Because Irma is so large, forecasters urged caution in paying too much attention to its exact track. The storm is continuing to roll west at 14 mph, with winds expected to begin battering the Leeward Islands today. A powerful high pressure ridge is steering the storm and will likely stay in place over the next few days, forecasters said. In five days, a trough moving across the U.S. should begin weakening the western edge of the ridge, allowing the storm to slide north. Where the Irma makes the turn will determine impacts to Florida.

In the Leeward Islands, forecasters warned catastrophic wind, storm surge could reach between six and nine feet, with pounding waves. Fierce hurricane winds extend 60 miles from Irma’s center, with tropical storm force winds reaching another 160 miles.

Dangerous conditions are expected to hit the Virgin Islands and Puerto Rico Wednesday.

At 11 a.m., Irma was located 225 miles east of Antigua, heading west at 14 mph. While wind speeds could fluctuate over the next day or two, forecasters say it will likely remain a very dangerous Cat 4 or 5 storm as it heads westward.

Hurricane warnings and watches extended across thenorthern Leeward Islands, with vulnerable islands prone to dangerous mudslides paying careful attention. Last year, Hurricane Matthew struck Haiti as a Cat 4 storm, leaving thousands homeless.

Irma is expected to move just northeast of the local islands Wednesday through Thursday, packing dangerous winds, storm surge, rip currents and heavy rain. Puerto Rico, where the governor has declared a state of emergency and is preparing to open 456 shelters that can house more than 62,000, could begin getting hit with tropical storm force winds as early as tomorrow.

In South Florida, the Keys would be the first region to undergo evacuation orders. Monroe County officials plan to activate their emergency operations center at noon today to begin announcing plans. Evacuations are generally ordered for any storm at Cat 1 strength or higher.

Across the mainland, the South Florida Water Management District has already begun lowering canals to make room for heavy rain and flushing as much water as possible to the coast and inspecting pumps and gates. The U.S. Army Corps of Engineers is also keeping a close eye on the aging dike around Lake Okeechobee, where water levels Tuesday were at 13.65 feet, still well below the 15.5 feet level where discharges begin and the more than 18 feet limit set to protect the dike.

While models have shifted Irma’s path up and down over the weekend, Tuesday morning’s runs largely agree on the storm’s path over the next three days, with less certainty after that.

0905 irma tidbits model

Tuesday morning model runs continue to show Irma turning to the north, but the timing of the turn will determine where impacts are felt in Florida.

Levi Cowan Tropical Tidbits

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After 24 hours, Irma is expected to turn slightly to the west, northwest, forecasters said. After four and five days, the storm’s track is less certain, with a margin of error of between 175 and 225 miles.

Over the last week, Irma has undergone repeated eyewall replacements, a common structural change for such massive storms. While the replacement may initially weaken the storm, it allows it to spread and grow in size. With each replacement, Irma has also been able to regain steam.