Tag Archives: Florida Panhandle

Hurricane Michael Field Reconnaissance: Contrasting Performance of Structures at Design Wind Speeds

Peter Datin, Director, Model Development, RMS

Derek Stedman, Lead Modeler, RMS

Holly Widen, Product Manager, RMS

 

Introduction

Hurricane Michael made landfall in the Florida Panhandle near Mexico Beach on October 10, 2018, as the strongest hurricane (by wind speed) to impact the area in recorded history. As a strong category 4 hurricane, Michael’s wind speeds were at or above the design-level wind speeds for this area specified by ASCE 7 and the Florida Building Code. Figure 1 below shows the RMS HWind 3-second peak gust footprint with the design wind speed contours from ASCE 7-16 for Risk Category II structures (e.g., single-family homes and most commercial structures).

Figure 1 : RMS HWind 3-second gust footprint for Hurricane Michael overlaid with the design wind speed contours in ASCE 7-16

The Florida Panhandle has historically considered itself less prone to intense hurricanes than other coastal areas such as the Greater Miami Area, where the probability of category 4 and 5 storms is much higher. As an example, in the history of the Florida Building Code (FBC), the Panhandle successfully lobbied for an exception to the windborne debris provisions that were introduced in the original 2001 FBC. This exception was ultimately lifted in 2007 but highlighted that this area contained many examples of pre-FBC construction side-by-side newer construction built to higher standards, featuring wind damage mitigation measures suggested by the engineering community and organizations such as the Insurance Institute for Business and Home Safety (IBHS).

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Comparing Major Hurricane Michael to Recent Gulf Hurricanes Using Integrated Kinetic Energy

Co-authors: Michael Kozar, Senior Modeler, RMS HWind; James Cosgrove, Senior Analyst, RMS Event Response

Michael underwent rapid intensification in the two days leading up to landfall, reaching the Florida Panhandle coastline as a strong Category 4 major hurricane with maximum sustained wind speeds of 154 miles per hour (247 kilometers per hour), according to the RMS HWind real time service. At landfall, Michael had a tight inner core and its strongest winds were located just 14 miles (22 kilometers) south-southeast of the center of the storm near Mexico Beach. Tropical storm force winds extended up to 115 miles (185 kilometers) eastward along the Panhandle coastline to Pensacola.

Whilst the Saffir-Simpson Hurricane Wind Scale (SSHWS) is exclusively based on maximum sustained wind speeds, which often only covers a very small part of the system, the Integrated Kinetic Energy (IKE) metric conveys the intensity, size, and structure of the storm’s wind field into one number and has become a useful metric for comparing the destructiveness of storms. Using the IKE metric, we can compare and contrast Hurricane Michael to other events in the RMS HWind historic archive.

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The Full Extent of Michael’s Impact Becomes Clear

From first light yesterday (October 11), the full extent of the damage from Major Hurricane Michael across the Florida Panhandle and the wider region became clear — and it really was as catastrophic as we all had feared.

Although Major Hurricane Michael could be regarded as a more traditional “wind and surge” event compared to recent flood events of hurricanes Harvey and Florence, this was not just a coastal event. The trail of destruction extends far from the landfall location near Mexico Beach (pop. ~1,000) and neighboring Panama City (pop. ~36,000) and well into the state of Georgia. Whether it is from the destruction of homes in the towns near landfall, or the widespread power outages, felled trees, damaged roofs, and debris, the clean-up operation is going to be a long process. And tragically, as of Friday, October 12, eight fatalities have been confirmed, including four in Florida, one in Georgia, and one in North Carolina.

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Hurricane Michael: Record Breaker

In its short life, Hurricane Michael has certainly developed quickly —  it only achieved tropical storm status just four days ago on Sunday, October 7.  And now, according to the latest bulletin from the National Hurricane Center (NHC), as at 12:00 UTC today, Michael has strengthened further, into an extremely dangerous Category 4 major hurricane, with maximum sustained wind speeds of 145 miles per hour (233 kilometers per hour).

The 09:00 UTC NHC bulletin placed Michael at about 140 miles (225 kilometers) south-southwest of Panama City, Florida, tracking north at 13 miles per hour (20 kilometers per hour). Hurricane-force winds currently extend outward up to 45 miles (75 kilometers) from the center and tropical-storm-force winds extend outward up to 185 miles (295 kilometers). According to the latest RMS HWind Forecast Storm Track Probabilities and Deterministic Scenarios chart (pictured below), Panama City has a 95 percent probability of the center of Michael passing within 50 miles.

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