According to the latest national weather forecast, Hurricane Irma is headed straight for Florida. Puerto Rico will get hit first, on Wednesday. Both Puerto Rico and Florida have declared a state of emergency as Irma Strengthens to Category 4.

Above: Visible-wavelength satellite image of Hurricane Irma as of 15Z (11 am EDT) Monday, September 4, 2017. Image credit: RAMMB / CIRA @ CSU.

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 is still 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.

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.

Threat Increasing for Cuba, Florida from Intensifying Irma

Weather Underground reports Threat Increasing for Cuba, Florida from Intensifying Irma.

Based on Hurricane Hunter measurements, NHC raised Irma’s top sustained winds at 5:00 pm EDT to 130 mph, making it a Category 4 storm. Irma is expected to be a major Category 4 hurricane when it passes very close to the northern Lesser Antilles Islands on Tuesday, near Puerto Rico and the Virgin Islands on Wednesday, and the Turks and Caicos Islands and Hispaniola on Thursday. As of 5 pm EDT Monday, Hurricane Warnings are in effect for the northern Leeward Islands, and Hurricane Watches are up for the U.S. and British Virgin Islands and Puerto Rico.

Tropical storm-force winds are expected to begin affecting the east coast of Florida and the Florida Keys on Friday night. An evacuation decision for the Florida Keys may have to come as early as Tuesday, since the Keys require 3+ days to evacuate. As of 5 pm EDT, far southeast Florida, including Miami, was in the 5-day cone of uncertainty for Irma.

Our most reliable intensity models–the HWRF, COAMPS-TC, LGEM, and DSHIPS–predicted in their Monday morning runs that Irma would peak as a Category 4 or 5 hurricane with 130 – 160 mph winds, and the official NHC forecast of a Category 4 hurricane when it passes by the islands this week looks reasonable. The only major impediment to Irma’s strength would appear to be interaction with land; a close pass or direct hit on Hispaniola or Cuba could potentially damage or destroy the hurricane’s inner core and knock it down to Category 2 or 3 strength.

Possible Tracks

Clearly, there are lots of possibilities here. The best case for Florida is the worst case for Cuba. A direct, sustained hit on Cuba could weaken Irma if it takes one of the Western paths. A central path that bypasses Cuba directly then heads straight North over Florida is likely the worst case for Florida.

The models have shifted dramatically in the past 12 hours and could shift again. The Weather Underground says that it is unclear exactly why the modeled track shifted so dramatically on Sunday night.

Bottom line from the Weather Underground: “It is becoming more likely that Irma will move close enough to the northern Leeward Islands, Puerto Rico, Hispaniola, and/or Cuba for significant impacts. There is an increasing chance that Irma will strike the U.S. late in the weekend or early next week, quite possibly as a major hurricane. It is still too soon to predict the location or timing of any U.S. landfall with confidence.”

Here are some Hurricane Preparation Tips from the US government.

Mike “Mish” Shedlock