Hurricane Irma Update – South Florida, Both Coasts, Pay Close Attention…


The latest update from the national hurricane center lists Hurricane Irma as a strong category 4 storm with wind speeds of 150 MPH.  However, strengthening is anticipated and Cat 5 scale begins at 157 MPH.   At 5:00am the eye was located at latitude 16.6 North,
longitude 56.4 West, moving West at 13 MPH. –ADVISORY HERE

Due to the severity of this storm and the uncertain forecast track, all Florida Residents South of I-4 on both coasts should be checking every update and begin verification of their  Hurricane supplies, hurricane plan and be paying close attention to local officials.

There is no cause for immediate alarm, and the storm’s path is likely to change and become more certain in the next 36/48 hours.  However, most models and forecasters are predicting a sharp turn to the right (North) sometime during the life of this storm; and with that in mind the timing of that turn will be critical for Florida residents.

If the storm does not turn North until later in the week, Irma could move up the East Coast (I-95 area), the center of the state, or the West coast (I-75 area).

If anything like that path is actually the end forecast direction of a Cat 4 or Cat 5 storm, the difference between 10 to 20 miles east or west will be extremely important.  I have led numerous Hurricane recovery teams, within multiple hurricane areas; this one is concerning.

Circulation is counterclockwise and Florida is a Peninsular with width of 90 to 120 miles in the South.

  • If the storm tracks North on the East Coast of Florida (I-95) the top of the storm will bring the surge, and the backside will push the outflow.
  • If the storm tracks North on the West Coast of Florida (I-75) the top of the storm will bring wind toward offshore, but the back side will bring in a massive storm surge from the shallow coastal Gulf of Mexico.
  • If the storm tracks North through the center of the state, both coasts will see coastal storm surges albeit with lesser severity.

Both SW (gulf side) and SE (Atlantic side) Florida coasts have large population centers and thankfully neither coast has seen a lengthwise hurricane path in many decades.  The worst case scenarios for Hurricane impact are within those possibilities.

♦Hurricane Andrew was a well-known catastrophic Cat 5 storm that hit the Homestead area South of Miami-Dade in 1992.  However, that storm –  as terrible as it was – was from East to West crossing the state and exiting in the Gulf of Mexico.  Florida has not had a South to North full impact hurricane in your lifetime.

♦Hurricane Charley was a lesser known strong Cat 4 storm (150 MPH) which tracked into the Gulf of Mexico and crossed the state from West to East in 2004.  Charley made initial impact through Upper Captiva Island (actually splitting the island in two) and hitting the mainland around Port Charlotte.  However, despite it’s Cat4 power Charley was a tight and fast moving hurricane and the damage was severe but narrow in path.

I’m providing those two references to highlight that South Florida has not had a South to North path hurricane in multiple decades.  There were probably less than two million residents in Florida the last time it happened; now there’s approximately 21 million.

For our friends in the Westward Keys and Southern Gulf Side (South West Florida), please pay particular attention to this current storms path.  Unlike the Eastern coast of Florida the South West coast (Gulf Side) is primarily made up of recently populated “shallow water” Gulf barrier Islands.  A Category 5 storm that skirts the Western coast of Florida, from Ten Thousand Islands Northward to Sarasota, and maintains inflow energy from the Gulf of Mexico, is a topography changing event.

Repeat: “A topography changing event.”

Shallow Water Coastal Vulnerability

In a scenario where Cat 5 Irma continues West or Northwest (current track), then takes a sharp right turn, Northward up the Southwest coast of Florida – before turning Northeast – the coastal vulnerabilities are almost too staggering to contemplate.

Beginning in the area of Everglades City and Ten Thousand Islands; northward through Marco Island, Naples Beach, Bonita Beach, Fort Myers Beach, Estero Island, Sanibel Island, Captiva Island, Upper Captiva Island, Useppa Island, The Caloosahatchee River inlet, Pine Island, Cape Coral, Bokeelia, Matlacha, Boca Grande as far North as Siesta Key and into the intracoastal waterway would be almost unfathomable in the scale of how the coastal topography would change.

These Islands, while they may not be familiarly referenced as “barrier islands”, simply because decades have past and populations have developed them, are exactly that “Barrier Islands”.  These shallow water gulf areas along the coast have not had severe storm surge disturbances for 60+ years.

The tenuous coastal and barrier island ‘ground‘ is crushed shell and sand, and their entire topography is subject to change as the shallow and severely churned gulf waters carry in sand/silt and excavate the same.

Just like 2004’s Hurricane Charley split an entire island in less than 15 minutes, so too could entire coastal communities be split or covered in sand within a few hours. Bridges rising from mainland on one side could disappear into the new coastal Gulf of Mexico on the other, with the barrier island completely removed.   Nature is a powerful force.

If you live in South Florida, please pay attention to Irma’s path.  There are millions of people in these coastal communities and only two basic Northern Interstates available for evacuation: I-75 (West Coast) and I-95 (East Coast).

If you live in South Florida West of I-75 or East of I-95, this might be the first storm you should consider *NOT* trying to ride out.

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