Hurricane and storm surge warnings for much of Florida for extremely dangerous Hurricane Milton » Yale Climate Connections

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  • Hurricane Milton is a potentially deadly threat. If you receive evacuation orders from local authorities, follow them.
  • The likely track will bring Milton into Florida’s west coast sometime on Wednesday evening or early Thursday morning, most likely near or just south of the Tampa Bay area.
  • The National Hurricane Center is forecasting 10-15 feet (3-4.6 m) of storm surge for a long stretch Florida’s heavily populated west coast.
  • Record hot sea surface temperatures in the area of the Gulf of Mexico where Milton formed were made up to 400-800 times more likely by climate change.

A Hurricane Warning and a Storm Surge Warning are up for much of both the west and east coasts of Florida, as Hurricane Milton races across the record-warm waters of the Gulf of Mexico toward an expected Wednesday night or early Thursday morning landfall. It is very likely that Milton will be a highly destructive hurricane costing over $10 billion for Florida – and Milton could end up placing among the costliest U.S. hurricanes on record, depending on the eventual details of landfall.

The risk is also high that Milton will be very deadly if people in low-lying areas do not heed evacuation orders and flee the hurricane. The National Hurricane Center continues to forecast up to 15 feet (4.6 m) of storm surge along a 70-mile (113 km) stretch of one of the most heavily populated portions of the U.S. coast, from Venice, Florida, northward to Tarpon Springs, including Tampa, St. Pete, Clearwater, and Sarasota. Up to 10 feet (3 m) of storm surge is predicted for an additional 50-mile (80 km) swath of heavily populated coast to the south, including Fort Myers.

Figure 1. Sea surface temperatures (SST) in the region where Hurricane Milton developed into a Category 5 storm were at or above record-breaking highs. In the region where Milton intensified from a Cat 4 to a Cat 5, SSTs were 31 degrees Celsius (88°F), about 1.8 degrees Celsius above the average for the time of year. A rapid attribution analysis determined that those temperatures were made up to 400-800 times more likely by climate change over the past two weeks. (Image credit: Climate Central)

Milton’s jaw-dropping ascent to the top tier of historic Atlantic hurricanes

Hurricane Milton put on an astonishing and unnerving feat of rapid intensification on Monday, topping out as a Category 5 storm with 180 mph winds and a central pressure of 897 mb at 8 p.m. EDT. This made Milton the fifth-strongest Atlantic hurricane on record (by pressure) and sixth-strongest by winds:

1. 190 mph (Allen 1980)
2. 185 mph (Dorian 2019, Labor Day 1935, Gilbert 1988, Wilma 2005)
3. 180 mph (Milton 2024, Mitch 1998, Rita 2005, Irma 2017)
4. 175 mph (nine storms, including Maria 2017, Katrina 2005, Andrew 1992, Camille 1969)

Milton’s eye shrank to an incredibly tight 4.6 miles, and an Air Force hurricane hunter aircraft reported that flocks of birds were trapped in the eye. The tightest eye ever observed was that of Hurricane Wilma of 2005, at 2.3 miles. Like an spinning ice skater wrapping their arms to speed up, hurricane eyewalls typically grow stronger as they shrink.

Milton is highly likely to be the fifth landfalling hurricane on the U.S. mainland in 2024. This would place this season in a tie with 2005, 2004, and 1893 as the second-most on record dating to 1851. Only 2020, 1985, and 1886, with six hurricane landfalls, have had more.

#Milton: Only the sixth known Atlantic hurricane with minimum central pressure below 900 millibars (mb).Wilma (2005): 882Gilbert (1988): 888Rita (2005): 895Labor Day Storm (1935): 892Allen (1980): 899Note: Pressure data was not regularly recorded by the National Hurricane Center until 1979.

— Steve Bowen (@stevebowen.bsky.social) 2024-10-07T23:03:25.677Z

Track forecast for Milton

Milton has been lashing the northern portion of Mexico’s Yucatan Peninsula with heavy rains over the past day, and one drowning death in Campeche has been blamed on the storm. Milton is now pulling away from Mexico, and is on its way to Florida.

The models have some into decent agreement over the past day on Milton’s future track, zeroing in on a probable landfall between Spring Hill (50 miles north of the entrance to Tampa Bay) to Venice (40 miles south of the entrance to Tampa Bay). A number of ensemble members of the GFS and European model ensembles show a landfall as far south as Fort Myers, about 80 miles south of the entrance to Tampa Bay. But just because the models are in unison doesn’t mean they are correct! Here are the average track errors over the past five years of National Hurricane Center forecasts for the Atlantic, as we discussed in a July post:

48 hours = 79 miles (127 km)
36 hours = 60 miles (97 km)
24 hours = 44 miles (71 km)

These errors can be viewed as circles around a given forecast point within the “cone of uncertainty,” so they can occur from leftward or rightward swings as well as speed-ups or slowdowns. Note also that the cone itself is calibrated to encompass about two-thirds of all actual storm locations; in other words, at any given future point, a hurricane can be expected to fall outside the cone about a third of the time.

Intensity forecast for Milton

Milton was regrouping on Tuesday after a spectacular surge of rapid intensification on Monday that took it from a tropical storm to Category-5 status in just under 25 hours. Such bursts of strengthening cannot be sustained for long, and they are often followed by eyewall replacement cycles (ERCs) in which a small eye collapses and a larger concentric one takes its place over the course of a few hours. An ERC on Monday night eroded Milton’s 4.6-mile-wide “pinhole” eye, and a larger surrounding eyewall took over. As a result, Milton’s top sustained winds decreased somewhat while the width of its overall wind field increased. At 10 a.m. EDT Tuesday, a reconnaissance flight found a closed 13.8-mile-wide eye. Maximum sustained winds as of 11 a.m. EDT Tuesday were 150 mph, making Milton a high-end Category 4 storm. Satellite imagery early Tuesday afternoon showed Milton’s eye sharpening (though some erosion on the north side was apparent, because of high wind shear), and Hurricane Hunters found the central pressure was beginning to drop.

Milton will have favorable conditions for at least maintaining its Category 4 strength through Tuesday night as it passes over record- to near-record-warm sea surface temperatures for early October, around 29 degrees Celsius (84°C) – only slightly cooler than those in the Bay of Campeche, where Milton rocketed to Cat 5 strength. Milton is not explicitly predicted to regain Cat 5 status, but such a resurgence cannot be ruled out, particularly as Milton passes over a pocket of deep oceanic warmth associated with the Loop Current of the Gulf of Mexico. If another ERC were to occur (see below), it could cause Milton’s peak winds to drop by 10-20 mph (16-32 km/h), but it would spread hurricane-force winds over a larger area, increasing the storm surge potential.

Through the day Wednesday, wind shear will be increasing along Milton’s track, and dry air will be infiltrating the storm from the west. However, a strong jet stream across the eastern U.S. may help serve as an outflow channel, helping Milton to remain vigorous (a similar process occurred during Category 5 Hurricane Michael’s approach to the Florida Panhandle in October 2018). The high-resolution intensity models used by the National Hurricane Center – including HAFS-A, HAFS-B, HMON, and HWRF – closely agree on bringing Milton toward the coast on Wednesday at Cat 3 strength. They also show Milton as a considerably larger hurricane than on Monday and Tuesday. With a storm like Milton, residents should not focus on the predicted intensity at landfall, as Milton will be pushing an immense and extremely dangerous amount of water en route to the coast regardless of its landfall strength (see surge discussion below).

A devastating storm surge is likely even if Milton weakens to a Cat 2 or Cat 3 at landfall

Milton’s tremendous Cat 4 and Cat 5 winds over the past two days have put a large amount of ocean water on the move. If Milton weakens significantly to Cat 2 or Cat 3 strength by landfall, as currently predicted by most of the hurricane models and the official NHC forecast, this process will spread Milton’s strongest winds over a wider area of ocean, increasing the volume of water put in motion. When Milton crosses over into the shallow waters of the continental shelf, 90 miles (145 km) offshore of Florida, this swirling water will form a large dome that will push onto the shore, creating a massive and destructive storm surge that will be more characteristic of a Cat 3 or Cat 4 hurricane than a Cat 2 or Cat 3 hurricane. A sobering fact: three of the most destructive Atlantic hurricanes on record were former Cat 4 or Cat 5 storms that were weakening in the 12 hours leading up to landfall. These include the costliest weather disaster in world history (Hurricane Katrina of 2005, with $191 billion in damage; Cat 5 peak, Cat 3 at landfall), Hurricane Rita of 2005 ($28 billion; Cat 5 peak, Cat 3 at landfall), and Hurricane Opal of 1995 ($10 billion; Cat 4 peak, Cat 3 at landfall) (h/t to Matt Lanza).

On Monday, Milton was a small hurricane with tropical-storm-force winds that extended out 80 miles (130 km) from the center. But after undergoing an eyewall replacement cycle overnight, Milton expanded in size, and winds extended out up to 105 miles (170 km) from the center at 11 a.m. EDT Tuesday. Another ERC may be coming later on Tuesday (see Tweet below), which would further increase the Milton’s size and surge potential.

Even more expansion of the wind field is expected on Wednesday as the hurricane interacts with a low-pressure system to the north of Florida and a front over the state. This interaction will inject energy into the hurricane, causing its wind field to expand (baroclinic forcing, the same process that made Hurricane Sandy of 2012 the largest Atlantic hurricane on record). At the time of landfall, the National Hurricane Center is predicting Milton will be much larger, with tropical storm-force winds extending out up to 220 miles (355 km) from the center. This large wind field is likely to bring the highest storm surge on record along an 80-mile (130-km) swath of Florida’s west coast near and to the right of where the eye makes landfall.

The timing of Milton’s landfall will be a significant factor in determining how much coastal flooding occurs. The difference in water level between high and low tide is about 2.2 feet (0.7 m). Low tide at St. Petersburg, Florida, is Wednesday afternoon near 2 p.m. EDT; high tide is near 6 a.m. Thursday. The peak surge (the height of the water above what would normally occur) will occur at the time of landfall, which the National Hurricane Center is currently predicting will be around 1 a.m. EDT Thursday: between mid-tide and high tide. If this timing holds, water levels will at most about half-a-foot lower than if Milton were to hit at high tide. The timing of Milton’s landfall among the 6Z Tuesday runs of the main models ranged from midnight EDT Wednesday (GFS model) to 7 a.m. EDT Thursday (HWRF model).

Nail-biting time in Tampa Bay

The National Hurricane Center forecast at 11 a.m. EDT Tuesday called for a landfall near Bradenton, just south of the entrance to Tampa Bay, near 1 a.m. EDT Wednesday. If this landfall location were to occur, Tampa Bay would experience hurricane-force offshore winds, which would blow water out of the bay and prevent a massive 10-15-foot storm surge. A lesser surge of 3-6 feet would be likely in the bay as the storm moved inland to the northeast, bringing onshore flow along the backside of Milton.

But if Milton were to make landfall slightly to the north, near Clearwater Beach, the powerful right-front winds of the hurricane would push water directly into Tampa Bay, bringing a massive 10-15-foot storm surge. A wobble of a mere 15 miles in track would make all the difference, with tens of billions in storm surge damage occurring with a more northerly track, but just a few billion with a more southerly one. Even the intensity of thunderstorms on the north side of Milton as it makes landfall could help influence such a wobble. We likely won’t know until just six hours or less before landfall whether or not Tampa Bay will see a disastrous storm surge.

The difference in storm surge between these two scenarios is stark for Tampa Bay, as seen in Fig. 2, which shows runs of the ADCIRC storm surge model for each case. But in both cases, Sarasota receives a brutal storm surge in excess of 10 feet, with the barrier islands of Longboat Key, Siesta Key, and Lido Key almost completely submerged.

Storm surge forecast for Tampa Bay
Figure 2. Storm surge forecast for Milton using the ADCIRC model, initialized with the 5 p.m. EDT Monday NHC forecast track and intensity forecast (left) and their 11 a.m. EDT Tuesday forecast (right). A landfall location just north of Tampa Bay (left plot) would bring a devastating storm surge in excess of 10 feet into Tampa Bay, while a landfall Location just to the south (right plot) would keep surge height generally below five feet in the bay. Use these plots with caution! These single model runs do NOT provide any uncertainty information, and provide the water height in feet above mean sea level (MSL). The difference between MSL and where normally dry ground (the metric used by NHC for their water height numbers) is roughly a foot for this portion of Florida. Thus, the forecasts on this map of 10 feet above MSL would be roughly equivalent to an NHC forecast of nine feet of inundation. (Image credit: CERA)

Life-threatening and catastrophic inland flash flooding is probable with Milton

Inland flooding is yet another very serious threat that Milton will bring, particularly near and just north of the eventual track. The corridor of heaviest rain will be close to the Tampa-St. Petersburg and Orlando areas. The NWS Weather Prediction Center has issued a rare High Risk for excessive rain and flooding on Thursday along this expected swath, where three-rain rainfall could total 8 to 16 inches. “Widespread and numerous instances of flash flooding are expected with life-threatening and catastrophic flash flooding probable,” the center warned.

High Risk areas for flooding are issued on only a handful of days each year, but they account for a third of all U.S. flood fatalities and about 80% of flood damage. With Milton, the situation will be exacerbated by storm surge and tidal flooding, which can serve to block rainwater from flowing out to sea and accentuate flooding well inland from the coastal surge. Rainfall will be considerably less south of Milton’s track, as dry air is pulled around the south side of the hurricane. However, even isolated downpours could cause localized flash floods where soils have been saturated over the past several days by rains ahead of Milton, especially across South Florida.

The dry-air intrusion may feed into a narrow corridor of damaging winds just south of Milton’s center, extending eastward across central Florida, that could see sustained winds of up to hurricane strength. South of this corridor, models suggest that fast-moving thunderstorms will develop late Wednesday and sweep across much of central Florida on Wednesday night, likely producing at least a few short-lived but still-dangerous tornadoes.

Florida’s insurance and coastal property market at risk

As explained in an August essay, When will climate change turn life in the U.S. upside down?, the Florida insurance and coastal property market did manage to withstand the $117-billion cost of Category 4 Hurricane Ian of 2022, but another blow like that might well cause a severe downward spiral in the Florida real estate market from which it might never fully recover. This vulnerability was underscored by Florida Gov. DeSantis during a 2023 radio interview with a Boston host, when DeSantis suggested homeowners should “knock on wood” and hope the state didn’t get hit by a hurricane in 2024.

But “knocking on wood” is not an effective climate adaptation strategy for Florida. Because of climate change, Mother Nature is now able to whip heavier bowling balls with more devastating impact down Hurricane Alley. Quoting from the post, “It’s only a matter of time before she hurls a strike into a major Florida city, causing an intensified coastal real estate and insurance crisis. And the odds of such a strike are higher than average in 2024 because of record-warm ocean temperatures in the tropical Atlantic, combined with a developing La Niña event.”

YouTube video

Like this hyper-strike rolling robot, Mother Nature is now able to whip heavier bowling balls with more devastating impact down hurricane alley because of the extra heat energy in the oceans from human-caused global warming.

So here we are, then, with another extreme hurricane, likely made more intense by climate change, threatening to bring Florida another $100-billion loss event. Most of Milton’s damage will be from storm surge, which state insurers have little exposure to (the federal National Flood Insurance Program holds the vast majority of the flood insurance policies in the state). But the hurricane is expected to bring damaging winds to a vast swath of dense housing units built before the strict Florida building codes went into effect after Hurricane Andrew of 1992 (see Tweet below). (See also this analysis by Dr. Kelly Hereid showing that more than 50% of housing in seven coastal counties is of older pre-Hurricane Andrew stock.)

Will Milton be the blow that sets in motion a long downward spiral for the Florida and U.S. coastal property market? In the event Milton’s landfall causes tens of billions in losses, it’s likely that the state and federal government will throw plenty of money into Florida to prop up this failing system to prevent this from happening, but as explained in, When will climate change turn life in the U.S. upside down?, climate change will inevitably cause a crash in the coastal property market, probably sometime in the next 15 years. If Milton does not cause the crash, a future storm will –or the system may simply crash on its own.

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