Sun. Feb 5th, 2023
Hurricane Irma at sunrise on Friday, as seen in a GOES-16 photo.
Enlarge / Hurricane Irma at sunrise on Friday, as seen in a GOES-16 photo.

NOAA

On Thursday afternoon, Eric Blake, a hurricane specialist at the National Hurricane Center and one of the nation’s leading experts on these storms, took to Twitter to offer some capstone thoughts on the storm bearing down on Florida. “Irma made me feel sick,” He wrote. “Must be very lucky to miss Florida now.”

Blake lives in Miami, like the rest of the NHC forecasters, and said Irma “gives chills” to residents there. “This hurricane is as severe as I’ve seen. No hype, just the hard facts. Take all the life-saving precautions you can. I have no doubt that Irma will go down as one of the most infamous in the history of the Atlantic Hurricane.”

This is a sobering message from someone like Blake, who mostly preaches calm and preparedness during hurricane season. Here he says a realistic worst-case hurricane is coming to the state of Florida. As we’ll discuss below, some intensity and track questions remain, but parts of the state will be hit exceptionally hard.

Intensity

A hopeful sign Thursday night and Friday was a general weakening of Irma, from 175 mph to 150 mph (as of 8 p.m. ET), bringing the storm just below Category 5 hurricane status. For the past few days, the storm has remained abnormally strong – usually a hurricane will increase in intensity and then quickly fall back down when it reaches Category 5 winds. The crucial question now is whether the storm will stay that way, weaken further or flare up again.

Blake and his colleagues at the National Hurricane Center predict that Irma will remain at about this intensity until it reaches Florida and makes landfall as a 150 mph hurricane. But they offer some caveats: If Irma’s center sinks over Cuba, that island’s mountainous terrain could weaken it somewhat; and second, the storm could weaken a little further as the inner eyewall reforms and then strengthen again before making landfall.

Irma will travel through warmer waters for the next 24-48 hours.  If the center moves inland over Cuba, that should weaken the storm.
Enlarge / Irma will travel through warmer waters for the next 24-48 hours. If the center moves inland over Cuba, that should weaken the storm.

Weerbel/Ars Technica

Several of my fellow forecasters believe the latter is likely, and some of the global models show a “deepening” of the storm as it moves into the Florida Strait. As noted on Ars Thursday, the waters are exceptionally warm between Cuba and the Bahamas. Provided Irma stays off the coast of Cuba and completes its eye wall replacement cycle, it could very well lead to re-strengthening into a Category 5 hurricane before making landfall on Saturday or Sunday.

To be perfectly honest, the physical processes of hurricane intensification are not fully understood, which is why they are imperfectly modeled by computer systems. So while it’s good that Irma is weakening now, that only goes so far. A Category 4 hurricane is still highly destructive, and Irma could strengthen significantly over the next 24 to 48 hours.

Track

On Thursday we also talked about reducing the chances of Irma’s job changing, but that doesn’t mean there isn’t a chance of it changing. There was indeed a slight westward shift in the National Hurricane Center’s official track during the overnight hours.

5 a.m. ET Friday track forecast for Hurricane Irma.

5 a.m. ET Friday track forecast for Hurricane Irma.

National Hurricane Center

This track is essentially a worst-case scenario forecast for South Florida, as it pummels the state with extremely dangerous winds, about 10 to 20 inches of rainfall, and a potentially catastrophic storm surge inland through South Florida, from Naples to the Florida Keys and beyond. coast through Miami.

However, this track is not set in stone. Some of the major forecasting models, including the GFS model and the European model, have shifted a bit to the west overnight. They both show a powerful storm moving across the Florida Keys and Everglades National Park before moving through the backbone of the state.

GFS ensemble forecast for Sunday at 2 a.m. ET.  Most of the members have the storm over the Keys, heading for the Everglades.
Enlarge / GFS ensemble forecast for Sunday at 2 a.m. ET. Most of the members have the storm over the Keys, heading for the Everglades.

Weerbel/Ars Technica

There are some subtle differences in these models, but they send a pretty clear signal that Irma is unlikely to miss Florida by turning north and staying east of the peninsula. On the contrary, there appears to be an increasing rain and wind threat for Fort Myers, Naples and southwestern parts of the state.

00z European model forecast for central Irma at 8 p.m. ET Sunday, after making landfall and traveling through Florida.
Enlarge / 00z European model forecast for central Irma at 8 p.m. ET Sunday, after making landfall and traveling through Florida.

Tropical Delights/Ars Technica

What remains crystal clear is that an extremely dangerous hurricane is heading into South Florida this weekend, with rain and wind threats extending north through most of the state and likely into Georgia and the Carolinas. While we can’t say exactly which areas will be hit hard, parts of Florida will certainly experience extreme damage.

By akfire1

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