Folklore and hurricane category don’t matter
There is a folklore surrounding why hurricanes do not make landfall in Sarasota! One version of the folklore suggests that Native American blessings or the presence of ancient burial grounds in the area provide protection from hurricanes. Some believe that the Native Americans who lived in Sarasota knew it was a safe place and chose to settle there for that reason. While these tales are captivating, it is essential to recognize that they are not rooted in historical fact. Currently, the Sarasota and Tampa areas are bracing for what could be one of the top ten most destructive weather events in U.S. history, with these Tropical Updates referring to it as a classic "Gray Swan" event. If a direct landfall on Tampa of Category 4 winds and surge occur, current losses could rival the 1926 Miami hurricane or the 1928 Lake Okeechobee hurricane and Katrina in 2005. This will all depend on track and intensity at landfall, which is starting to narrow, but right now, it is likely that insurance losses will be at least $25B in the best possible forecast scenario if Milton falls apart due to shear and dry air before landfall.
In today’s update, we can refine the expected landfall area and intensity, with the average error for a 36-hour forecast being around 36 miles and an intensity error of about 8.5 mph. It is important to remember not to focus solely on the storm’s category, but rather on the full range of potential impacts Hurricane Milton could bring. Even if Milton makes landfall as a standard Category 3 on the Saffir Simpson Scale, other factors can play into damages. As we pointed out in yesterday's Tropical Update, recent storms like Rita (2005), Katrina (2005), and Ike (2008), all of which were large, powerful hurricanes in the Gulf of Mexico that weakened before landfall still caused $10’s of billions in insurance industry losses. Milton will be no different as the wind field will expand in size, and the system could become asymmetric. Impacts could be lopsided from a typical hurricane landfall. In fact, the hurricane center's official forecast shows that hurricane and tropical-storm-force winds will roughly double in size when Milton makes landfall, which is also shown in the BMS division Verisk Respond 3-second wind swath product below. The heaviest rain will be along the north side of the storm track, which could result in flooding problems.
One of the biggest changes in the overall forecast besides the time of landfall, which looks like it will be around 1 am Thursday, Oct 10th, is that a few hurricane-specific models suggest a stronger storm at landfall, Category 4. The other noticeable change is that the structure of Milton has changed significantly overnight. Milton underwent an eyewall replacement cycle, which is common in strong hurricanes and often causes the peak winds to fluctuate while the wind field generally expands. This wind field expansion will be critical to the insurance impacts upon landfall. So, while some models show some weakening, the extent of the wind field will expand, causing more expansive areas of damaging winds. Still, of course, this will enhance the storm surge with Milton, which will likely be one of the biggest stories as storm surge could realistically reach Category 5 levels. Some forecast models suggest that wind shear will increase upon landfall and that dry air might take over. The forecast model in the other camp with a stronger landfall keeps the hurricane's core intact, which is why Milton could be stronger at landfall and cause even more insurance loss.
Milton Forecast Landfall and Intensity
In just four hours yesterday, Hurricane Milton intensified from a Category 1 to a Category 4, and by 1 pm, it had reached Category 5. While the rapid escalation to Category 5 might seem surprising, nearing record speed, it is best understood by comparing it to a figure skater’s spin. Milton had a small core, and much like a figure skater pulling their arms in to spin faster, the compact structure allowed it to intensify rapidly. When a skater’s arms extend, more effort is needed to maintain speed—similar to how larger hurricanes require more energy to strengthen. Milton reached its theoretical maximum intensity due to ideal ocean and atmospheric conditions. However, following an eyewall replacement cycle, the storm has since weakened, which is typical of the intensity fluctuations seen in stronger hurricanes. Fluctuations in strength due to continued structural changes likely occur the next day while Milton moves across the Central and Eastern Gulf of Mexico, which has record-warm sea surface temperatures (SST) and almost perfect environmental conditions. This means that Milton could once again archive Category 5 hurricane status. An increase in vertical wind shear will likely cause some weakening before the hurricane reaches Florida, but there is high confidence that Milton will be a much different storm. Landfall is still expected at the Longboat Key, FL. But a swath up or down the coastline from Clearwater, FL, or Venice, FL, is still possible.
While much of the focus is on the Tampa Bay region's landfall, which is still recovering from Hurricane Helene ten days ago, it should be noted that the entire I-4 corridor is highly populated, and impacts could be felt well inland into Orlando. The Northeast coast of Florida will also see damage as onshore flow and storm surge impact areas alone as the storm continues to expand in size after landfall.
Building codes
The overall wind gust is essential for wind damage, but the building stock is more important. Pinellas County has the highest concentration of old construction in the Tampa Bay Area. We have already highlighted the Disaster by Design that has occurred, and perhaps the best way to show this is through the work of Stephen Strader at Villanova University.
As you can see from the image above, the Tampa Bay area building stock varies widely in age, reflecting the region’s growth over different periods. Many residential and commercial buildings date back to the mid-20th century, particularly from the 1950s to the 1980s. However, there has been significant development in recent decades, with a notable increase in new constructions from the 2000s onwards. The Florida Building Code (FBC) governs the wind building codes in Tampa Bay. The FBC incorporates standards from the American Society of Civil Engineers (ASCE) 7-16, which includes specific wind load criteria. This means new construction requires buildings in the landfall area to withstand wind speeds ranging from 140 mph to 160 mph, depending on the specific location within the region. Structures within one mile of the coastline require windows to be impact-resistant or protected and to withstand wind speeds of 110 mph or greater. These codes are designed to ensure buildings can withstand the high winds associated with hurricanes, however older homes do not have these same requirements.
At this time, Peak gusts of 110-115 mph, inland areas of 90-100 mph, and along the east coast of Florida 60-75 mph should not destroy well-built homes. These winds compromise roofs and cause damage to the structure, but most roofs/walls will remain in place, with the exception of manufactured homes, specifically the older ones. In well-built framed houses, the strongest wind gust zone may incur major damage or removal of roof decking and gable ends. Across the state, many trees will be snapped or uprooted, blocking numerous roads due to the saturated soil conditions. Additionally, electricity and water will be unavailable for several days to weeks after the storm passes.
Historical landfalling hurricanes, such as Hurricane Ian and Helene in the Big Bend region, demonstrate that newer roofs can significantly reduce wind damage during storms. Roofs that are 0-5 years old tend to perform the best, while those that are ten years or older experience greater losses. A key concern is the number of roofs replaced in recent years due to Florida's Assignment of Benefits (AOB) issues.
Storm Surge Impacts
These tropical updates have already illustrated how sensitive Milton's storm surge is to the overall landfall location. Now that we have a clearer picture of the landfall timing, it is crucial to consider the tide as well. For instance, Sarasota’s low tide occurs at 1:01 PM on Wednesday, October 9th, while the high tide is at 4:27 AM on Thursday, October 10th. This means the tide will be rising as the storm surge moves in, with another low tide occurring at 2:25 PM on Thursday, October 10th.
The worst-case scenario would involve Milton making landfall as a major hurricane along the Pinellas Peninsula, bringing the worst possible storm surge flooding into Tampa. It is important to highlight that Tampa is highly vulnerable to storm surges due to its expansive, gently sloping basin. This characteristic, coupled with the strong onshore winds of a major hurricane, can lead to devastating outcomes. The last time this happened was the 1921 Tampa Bay hurricane, which made landfall as a Category 3 hurricane and brought 10-12 feet of storm surge flooding to the city. As we have pointed out in past tropical updates, if landfall is south of Tampa, it would likely result in a significantly reduced storm surge threat for the Bay – instead of water rushing in, the water would rush out of the bay.
Given forecast uncertainty, it is essential to consider all possibilities and avoid relying too heavily on any single forecast or hurricane category. Also, remember that the northeast coast of Florida and the coasts of Georgia and South Carolina could also see storm surge impacts. The worst flooding on the east coast will likely be from the Flager / Volusia County Line in Florida northward to the Altamaha Sound in Georgia, where 3 to 5 feet of storm surge will be possible.
Watercraft Impacts
One impact that needs to be more widely discussed is the impact on watercraft. The Tampa Bay area, including St. Petersburg, is a popular spot for boating. Unfortunately, we just saw Hurricane Helene's storm surge, which caused numerous watercraft to be pushed up or damaged on land. With Hurricane Ian, it is estimated that more than 10,000 boats were destroyed in its record storm surge along Fort Myers and Cape Coral. Still, there is an even greater amount of watercraft around Tampa/ St Petersburg and Sarasota that correlates with the increase in population along this heavily developed coastline, with estimates suggesting over 400,000 registered boats in the region. Given the large number of boats owned by snowbirds and the inability to remove/move or tie down watercraft, damage will be very high.
Environmental concerns and complications
These tropical updates have flagged the hazard of debris left by Helene as a factor to be aware of. Although there was a frantic push to remove debris, a lot remains. On top of the expected record storm surge, depending on the track, this debris will be an environmental disaster as the water comes in, picks it up, and pushes it around. Still, much of the water could be drawn back into the ocean when it recedes and, with it, a lot of debris.
Another factor the insurance industry must consider is the challenges faced by claims adjusters in determining which event caused a loss. While Helene was primarily a storm surge event, the additional time for adjusters to evaluate potential water-only claims has highlighted complications. If a structure experiences both water and wind damage, this can complicate the claims process significantly, ultimately increasing the overall loss claims expenses. Additionally, with the damage expected, this could become a super-demand surge event, and the price for goods and services will skyrocket as snowbirds look to rebuild during the winter months.
It's more than just Folklore at this point
It is still entirely too early to pinpoint an accurate insurance loss range. A storm making landfall in Tampa Bay would be a historic loss for the insurance industry and likely change the insurance market for years. The landfall along Sarasota is much more manageable for the industry and similar to Ian. Yet at this point, it is safe to say this will likely be at least a $20B dollar event. This is solely based on a review of the low end of the catastrophic modeling guidance and some of the historical analogs like the 1921 Tarpon Spring / Tampa Bay Hurricane that today would cause over $25B in insurance industry losses. There is heavy discussion about climate change and stronger storms, but now is not the time to debate this fact. Just like folklore, we need to understand the data, which is limited. We need to remember that extreme weather events need a very long record. And remember, before the 1960s, there were significant assumptions about the track and strength of storms that were over the open ocean. Landfall data has been great since 1900. Milton serves as a prime example of how historical records have evolved. Prior to the 1960s, satellite data relied on observations from boats or land. With Milton being just 100 miles wide and having a 5-mile wide eye yesterday, we would have lacked detailed information about the storm without reconnaissance flights and satellite technology. For instance, as Milton passed near Merida, Mexico, winds only gusted to 30-40 mph.
Please take Milton seriously. The BMS Pathlight Analytics staff is here 24/7 to provide you with answers, not just output, regarding insurance impacts on the west coast of Florida.