Hurricane Irma strengthens to Cat 4, Florida now in forecast track
By Tribune News Service
Sep 04, 2017 | 7:45 PM
As of 5 p.m., Hurricane Irma had grown in intensity from a Category 3 to a Category 4 as it approached the northwest Caribbean, where it is expected to strike Tuesday.
Florida is under a state of emergency as powerful Hurricane Irma's path became clearer Monday and chances of a tangle with the major tropical cyclone increased.
Gov. Rick Scott declared a state of emergency for all 67 counties, an announcement made minutes after the National Hurricane Center increased Irma to a Category 4 storm with 130-mph winds that are expected to increase to 150 mph during its trek west.
South Florida could begin feeling the first impacts from Irma late this week, and National Hurricane Center forecasters urged that preparations be completed by Friday.
While a shift in the forecast track away from Florida remains a possibility that would spare the Sunshine State the brunt of a direct hit, most models had settled on one of two scenarios — a Matthew-like storm skimming the east coast, or a system punching north through the keys to bisect the Peninsula.
The tip of Florida, including Miami, was in the 5-day track forecast cone as of Monday evening.
"What I want to convey is that you should have your hurricane plan and preparation done by Friday," said Dave Roberts, a specialist with the National Hurricane Center in Miami. "Don't freak out, but focus on your hurricane plan and preparations for any kind of impact."
The National Weather Service in Miami said the window of greatest concern is Friday through Monday. According to the NHC's new product that estimates when damaging winds may begin, Monroe through Palm Beach counties have between a 20 to 40 percent chance of feeling tropical storm-force winds beginning Friday.
As of the 5 p.m. Monday advisory from the hurricane center, Irma was a 130-mph Category 4 hurricane located 490 miles east of the Leeward Islands. The official forecast is for it to strengthen to 150 mph — still a Cat 4 — as it reaches the islands late Tuesday or early Wednesday. Irma could fluctuate in strength over the next several days depending on how much land it touches on its westward journey.
Hurricane-force winds extend outward up to 40 miles from Irma's center. Tropical storm-force winds extend 140 miles out.
Irma is expected to reach Puerto Rico on Wednesday with 145 mph winds. Puerto Rico's governor declared a state of emergency Monday for the U.S. territory ahead of the dangerous storm.
"Hurricane Irma is a major and life-threatening storm and Florida must be prepared," Scott said in his emergency declaration. "I have continued to be briefed by the Florida Division of Emergency Management on Hurricane Irma and current forecast models have Florida in Irma's path - potentially impacting millions of Floridians."
The forecast for Irma had the NFL considering moving up the season opener between the Miami Dolphins and Tampa Bay Buccaneers, or changing locations. Monroe County's Emergency Management activated its Incident Command Team on Monday. Palm Beach County's emergency management went to a level 3 activation, which means alerting county employees to the potential for an event to "escalate."
Irma's future, and that of the U.S. coastline, is dependent on two atmospheric features: the Bermuda High and an upper-level low moving west to east through the central U.S.
The clockwise churning high over the western Atlantic is what's keeping Irma on a westward track, moving it closer to Florida.
If the upper-level low catches Irma and shoots it north, the hurricane could parallel the east coast of Florida, similar to the path Hurricane Matthew took in October. If Irma misses the upper-level low, it could travel further west on a track that has it making an abrupt right turn into the Keys and the tip of the state.
"Both cases involve having a hurricane passing very close to the Palm Beaches on Sunday night or Monday," said Dan Kottlowski, a hurricane expert with AccuWeather. "The good news is, Floridians still have time to prepare."
The National Weather Service will be launching a series of special weather balloons in the center of the country to better gauge the upper-level low, how fast it is moving and its potential interaction with Irma. At the same time, the National Oceanic and Atmospheric Administration's Gulfstream jet will be taking upper-atmosphere measurements of Irma to get a better sense of its path.
The Leeward Islands is anticipating up to 6-feet of storm surge from Irma and isolated rain amounts as high as 10 inches. Kottlowski said he doesn't believe Irma will bring rain to Florida similar to the 50-plus inches Hurricane Harvey dumped on Texas, but a foot or slightly more isn't out of the question.