The 2012 hurricane season is the second most active one in recorded history so far, yet the season is just a little more than half over.
As September is typically the most active month, the potential for additional loses is high, according to modeling firm Risk Management Solutions.
The company estimates U.S. insured losses from Hurricane Issac’s wind and surge impacts on the U.S. Gulf Coast will fall between $1−2 billion, excluding rainfall driven flood losses and all National Flood Insurance Program losses.
This includes the possibility of a small amount of loss stemming from so-called coverage leakage, i.e., losses caused by surge inadvertently paid out by wind-only policies.
“We’ve formulated our estimate using a blend of modeling tools, combined with our assessment of key areas of uncertainty and non-modeled losses — excluding flood,” Dr. Christine Ziehmann, RMS director of model product management, said in a statement. “The width of the range reflects some remaining uncertainties, including the variability and uncertainty around loss at very low wind speeds—mostly tropical storm strength—and, in particular, the uncertainty around coverage leakage of surge related losses into wind-only loss payments.”
Hurricane Isaac made landfall in Louisiana on Aug. 28 as a Category 1 strength hurricane, near the mouth of Lake Mississippi, then made a second landfall of the same intensity near Port Fourchon, La. on Wednesday, Aug. 29. The storm then continued to move northwest very slowly across Louisiana, was downgraded to a tropical storm later that day, and finally dissipated on Sept 1, in Missouri.
A wide swath of strong winds, storm surge, and inland flooding were associated with Isaac, most notably across Louisiana and Mississippi, with further wind and rain damage affecting Arkansas.
Inland flooding caused by heavy rainfall was one of the major concerns from Isaac due to the storm being large in size and moving extremely slowly. Louisiana in particular was hit hard by rain from Isaac, though Alabama and Missouri also experienced heavy rainfall.
“From a wind-damage perspective, Isaac made landfall in the same area where Katrina and also Gustav made landfall in 2005 and 2008, respectively,” Ziehmann said. “Both these previous events impacted the building stock and eradicated a large portion of very low-quality roofs and buildings, which could mean that the wind losses fall into the lower end of the modeled range.”
The 2012 Atlantic Hurricane Season has seen 14 tropical storms, with 7 strengthening to hurricane status. Only one of these hurricanes has become a major hurricane – Hurricane Michael, which intensified into a Category 3 hurricane on Sept. 6, but only maintained that status for six hours.
So far the 2012 the season is the second most active season (tied with 1936) since records began in 1851, in terms of the number of named storms. Only 2005 and 2011 had more named storms as of Sept. 13.
Eight tropical storms formed in August, making August 2012 the most active August in terms of Atlantic basin tropical storm activity, tied with the 2004 season. We are just over half way through the 2012 season, and on average, are currently in the most active month.
Between 1950 and 2011 on average four tropical storms formed in September, with an average of five tropical storms forming in September between 1995 and 2011. (2004 had four tropical storms in September and 2005 had five tropical storms in September—all of which strengthened to hurricanes.)
“Seasonal forecasts for 2012, issued at the beginning of August called for around 14 tropical storms in the Atlantic in 2012,” Ziehmann said. “The 2012 season is currently on track to exceed these forecasts, especially if September is typical of the 1995-2011 average.”
A weak to moderate El Niño is forecast to develop during September, which has the potential to inhibit tropical storm development. However through the 2004 hurricane season a weak El Niño was prevalent, although there was still an above-average number of tropical storms, hurricanes and major hurricanes—the season closing with 14 tropical storms, nine hurricanes and six major hurricanes.
