- 4,001days: that is how long it has been since a major hurricane (Wilma) made landfall in south Florida. And today, Matthew, the violent end to the U.S major hurricane drought, rages into day two.
- Many of the hurricane models that forecasted a central Florida landfall were clearly wrong, as Matthew is currently 35 miles off the coast of Cape Canaveral as a 120-mph category 3 hurricane. Even the trusted ECMWF model predicted a central Florida impact yesterday. But there are some model winners. The BMS iVision Verisk Climate wind model never predicted a landfalling outcome. And yet again, we see that there is continued room for improving hurricane track and intensity forecasting.
- As I suggested on October 5, hurricane track will drive outcomes. I also mentioned that the storm size would make a difference, and Matthew’s hurricane force winds never really expanded.
- Matthew is now expected to parallel the Florida coastline and slowly weaken, so insured loss should be confined to near-coastal areas close to its current location and up to the southern North Carolina coastline.
- Matthew is forecasted to stall or loop near the southeast coast of the U.S.
Landfall and Wind Impacts
“Landfall” is defined as the center of low pressure that intersects with the coast. This has not occurred with Matthew. For several days, weather models suggested that Matthew’s ultimate landfall (or lack thereof) would be determined by just a matter of miles. What might be more interesting than whether or not Matthew makes landfall is the fact that the last two largest U.S. insured losses from a hurricane will ultimately be caused by storms that failed to make landfall. Sandy (2012) was never officially classified as a hurricane and thus didn’t make landfall. Matthew may never make landfall, but will still likely cause significant insured loss; most likely the highest insured loss since Sandy.
Matthew never grew in size as expected, and for the most part, always maintained a very small area of hurricane force winds. This area grew only nominally as it moved north as illustrated in the NHC wind history plot below.
Past extent of the hurricane force winds and tropical storm force winds
Matthew has maintained its track parallel to the Florida coastline overnight, as it never got pulled landward, and the hurricane-force wind around its small center of circulation have primarily stayed off shore.
This will likely mean that insured losses will be limited, so in some cases insurers will ultimately retain a greater portion of their losses (versus collecting on higher attaching reinsurance programs designed to respond to major natural catastrophes). These retentions could add up, especially since it has been 35 days since hurricane Hermine impacted the state and caused minimal insured loss primarily retained by insurers. Still, the full extent of insured losses will continue to develop as Matthew continues to track up the north-Florida, Georgia, and South Carolina coast.
I have yet to identify a hurricane-force wind speed recorded at an official weather station. The highest wind gust I have seen so far is 74 mph, recorded at Vero Beach, Florida. This would not translate into a hurricane-force wind, which must be measured at 1 minute resolution. There have been other reports of high wind, especially on the high tower near the Cape Canaveral coastline. Keep in mind, however, that many of these towers are hundreds of feet tall, and much higher than the official 30-foot measuring height. Other higher windspeed gusts could occur yet today as Matthew tracks very close to the Florida coastline.
Strongest wind guest from observations last nights
Although structures will likely sustain damage given the observed wind speeds, ultimate damage should be minimal. To illustrate, see the damage plot below for a pre-2002 home that experienced category2 wind speeds. The outcome shows 35% probability of at least roof sheathing damage. Probability drops to a 5% for a category 1, and even less for a tropical storm force wind.
General probability of at least roof sheathing damage vs wind speed
As one would expect, and as my blog previously suggested, flooding can be expected in Georgia and the Carolinas as Matthew tracks northward.
NOAA rainfall forecast showing 13 inches rainfall for areas of the coastline
Storm surge has not been as bad as forecasted. Areas with 9-foot surge forecasts ultimately experienced only 6-foot surges. However, high storm surge values are still forecasted for coastal Georgia and South Carolina as Matthew works it way northward. Currently some of the highest surge forecast values are found along the North Georgia.
Water value observed near Trident Pier, FL showing the build up storm surge at this station in this area and the fall of that water as the storm passed and the water gets pulled away from the shoreline.
Matthew Just Won’t Go Away
The burning questions seem to be, “Is Matthew really going to do a loop off the southeast coastline? Is this possible?” Yes, it is very possible, but also unusual.
Gordan (1994), Felix (1995), Ivan (2004) and Jeanne (2004) are all examples of looping storms. However, as indicated in the plot below, south or even southeast hurricane movement is rare, as most trajectories for Atlantic hurricanes track northeast.
Hurricane Gordon 1994 did a nice loop off the southeast coast
Another burning question is, “Will Matthew loop back and impact the Bahamas and Florida again?” It is possible and still a possible outcome on many of the long-range ensemble forecasts. My bet is that Matthew will loop northeast of the Bahamas, but then be kicked back out to sea toward Bermuda around Thursday next week.
ECMWF track model showing the chances of the Matthew getting back to Florida or Bahamas