Category Archives: Hurricanes

Revised 2018 Hurricane Season Forecast

By Phil Klotzbach, lead author of the Colorado State University (CSU) hurricane forecasting team, and I.I.I. non-resident scholar. 

Colorado State University (CSU) released its updated outlook for the 2018 Atlantic hurricane season today, and they are now calling for a below-normal season with a total of 11 named storms (including Alberto which formed in May), four hurricanes and one major hurricane (maximum sustained winds of 111 miles per hour or greater; Category 3-5 on the Saffir-Simpson Wind Scale) (Figure 1).  This prediction is a considerable reduction from their June outlook which called for 14 named storms, six hurricanes and two major hurricanes.  Accumulated Cyclone Energy (ACE) and Net Tropical Cyclone (NTC) activity are integrated metrics that take into account the frequency, intensity and duration of storms.

 

Figure 1: July 2, 2018 outlook for the forthcoming Atlantic hurricane season.

CSU employs a statistical model as one of its primary outlook tools.  The statistical model uses historical oceanic and atmospheric data to find predictors that worked well at forecasting prior year’s hurricane activity and has shown considerable skill based on data back to 1982 (Figure 2).  The statistical forecast for 2018 is calling for a below-average season.

Figure 2: Efficacy of statistical forecast model at predicting historical Atlantic hurricane activity since 1982.

CSU also uses an analog approach, whereby the team looks for past years with conditions that were most similar to what they see currently, and what they predict for the peak of the Atlantic hurricane season (August-October).  The forecast team currently anticipates below-average to near-average sea surface temperatures (SSTs) in the tropical Atlantic and warm neutral to weak El Niño conditions in the eastern and central Pacific.  This averaging of the five analog seasons also calls for a below-average season (Figure 3).

Figure 3: Analog predictors used in the July 2, 2018 seasonal forecast.

The primary reason for the reduction in the seasonal forecast was due to continued anomalous cooling of the tropical Atlantic.  Most of the Atlantic right now is much cooler than normal. (Figure 4).  In fact, current sea surface temperature anomalies in the tropical Atlantic are colder than any year since 1994.  In addition to providing less fuel for storms, a cooler tropical Atlantic is also associated with a more stable and drier atmosphere as well as higher pressure.  All of these conditions tend to suppress Atlantic hurricane activity.

Figure 4: Current SST anomalies in the North Atlantic.  SSTs are much cooler than normal across the entire tropical Atlantic.

CSU also believes that the chance has increased for a weak El Niño event developing to coincide with the peak of Atlantic hurricane season. El Niños tend to reduce Atlantic hurricane activity through increases in upper-level winds that tear apart hurricanes as they are trying to develop.  The dynamical and statistical model guidance is about evenly split between El Niño and neutral (neither El Niño nor La Niña) conditions for the peak of the Atlantic hurricane season (August-October) (Figure 5).

Figure 5: Statistical and dynamical model guidance for El Niño.  Model guidance is about evenly split between El Niño and neutral (neither El Niño nor La Niña) for the peak of the Atlantic hurricane season (denoted by the arrow).  Figure courtesy of International Research Institute for Climate and Society.

Coastal residents are reminded that it takes only one storm to make any hurricane season an “active” one. For example, CSU correctly predicted a quiet Atlantic hurricane season in 1992.  The season, in fact, was very quiet, with only seven named storms, four hurricanes and one major hurricane—but that major hurricane happened to be Hurricane Andrew, which tore across south Florida as a Category 5.

Philip J. Klotzbach, Ph.D. is Research Scientist, Department of Atmospheric Science, Colorado State University and an I.I.I. Nonresident Scholar. You can follow him on Twitter at @PhilKlotzbach

 

CoreLogic: 6.9 million homes worth over $1 trillion at risk for storm surge in 2018

Weather experts, including I.I.I. non-resident scholar, Dr. Phil Klotzbach, are predicting a slightly below average hurricane season for 2018, but that does not mean that the dangers of potential storm damage are negligible.

CoreLogic, an analytics company, released its annual Storm Surge report on June 5. The report found that along the Gulf and Atlantic Coasts, about 6.9 million coastal homes worth over $1 trillion are at risk. CoreLogic estimates reconstruction costs for 2018 increased 6.6 percent from a year ago, mirroring increased regional construction, equipment, and labor costs.

The Atlantic Coast has more than 3.9 million homes at risk of storm surge with reconstruction cost value of more than $1 trillion, up by about $30 billion from 2017. Gulf Coast homes with the same risk total more than 3 million, with more than $609 billion in potential exposure to total destruction damage, a $16 billion increase compared to 2017.

The reconstruction cost value is calculated based on 100 percent destruction of the residential structure, using the combined cost of construction materials, equipment and labor costs.

Updated 2018 Atlantic Hurricane Season Outlook: Cooler Atlantic Temperatures Could Lead to Below-Average to Near-Average Hurricane Season

Special to the Triple-I Blog

by Philip Klotzbach,Ph.D,
Research Scientist, Department of Atmospheric Science, Colorado State University and I.I.I. Nonresident Scholar

Colorado State University (CSU) has just updated their outlook for the 2018 Atlantic hurricane season, and is now calling for a near-average season with a total of 14 named storms, six hurricanes and two major hurricanes (maximum sustained winds of 111 miles per hour or greater; Category 3-5 on the Saffir-Simpson Wind Scale) (Figure 1).  This prediction is a slight lowering from their initial outlook in early April which called for 14 named storms, seven hurricanes and three major hurricanes.  Accumulated Cyclone Energy (ACE) and Net Tropical Cyclone (NTC) activity are integrated metrics that take into account the frequency, intensity and duration of storms.

Figure 1: May 31, 2018 outlook for the upcoming Atlantic hurricane season

CSU’s meteorological team uses a statistical model as one of its primary outlook tools.  This methodology applies historical oceanic and atmospheric data to find predictors that were effective in forecasting previous years’ hurricane activity. Based on data dating back to 1982, this model has shown consistent accuracy. (Figure 2)  Statistical forecast for 2018 is calling for a below-average season.

Figure 2: Accuracy of June statistical forecast model at predicting historical Atlantic hurricane activity (since 1982)

CSU also employs an analog approach, which uses historical data from past years with  conditions that are most similar to those currently observed (as of May 31, 2018).  The team also forecasts projected conditions during 2018 peak hurricane season (August-October) by looking at historical data from years with similar August-October conditions.

This approach yields a similar outlook of below-average to near-average sea surface temperatures (SSTs) in the tropical Atlantic and near-average sea surface temperatures in the eastern and central Pacific.  The average of the four analog seasons calls for a near-average season. (Figure 3)

Figure 3: Analog predictors used in the May 31, 2018 seasonal forecast

CSU does not anticipate a significant El Niño event for the peak of the Atlantic hurricane season.  At this point, the meteorological team believes that the most likely outcome is neutral conditions for the next several months.  El Niños tend to reduce Atlantic hurricane activity through increases in upper-level winds that tear apart hurricanes as they are trying to develop.  Most of the dynamical and statistical model guidance agrees with this assessment and calls for neutral conditions for the next several months. (Figure 4)

Figure 4: Statistical and dynamical model guidance for El Niño

Most models are calling for neutral conditions for August-October, as highlighted by the black arrow. (Figure courtesy of International Research Institute for Climate and Society.)

The primary reason for a reduced seasonal forecast (compared with earlier 2018 outlook), is due to anomalous cooling of the tropical Atlantic over the past couple of months.  As shown in Figure 5. most of the Atlantic right now is quite a bit cooler than usual. In addition to providing less fuel for storms, a cooler tropical Atlantic is also associated with a more stable and drier atmosphere as well as higher pressure—all conditions that tend to suppress Atlantic hurricane activity.

Figure 5: Current SST anomalies in the North Atlantic.  SSTs are much cooler than normal across the entire tropical Atlantic

The most important thing to note with all seasonal forecasts is that they predict basinwide activity and not individual landfall events.  However, regardless of what the seasonal forecast says, it only takes one storm near you to make it an active season.  Therefore, coastal residents are urged to have a plan in place now before the hurricane season ramps up over the next couple of months.

Extra: If you live in a hurricane-prone region, your homeowners insurance policy may have a separate hurricane deductible. This infographic explains what you need to know.

The brown ocean effect – a trend to keep an eye on

Tropical cyclones usually weaken after they make landfall, but under certain conditions they may intensify or maintain their strength. This is called “the brown ocean effect,” a phenomenon when a large area of hot soil (usually a desert) is soaked by rain from a tropical storm, releasing heat into the atmosphere and fueling the storm. This phenomenon also requires that the lower level of atmosphere resembles a tropical one, and that there is minimal variation in temperature.

These conditions are most likely to occur in Australia, but can also happen in the U.S. and China, according to a recent AIR Worldwide blog post. A NASA-funded study that looked at 227 tropical storms between 1979 and 2008 found that after making landfall, 16 storms, including Tropical Storm Erin, maintained their tropical warm-core characteristics over land, and effectively became “brown ocean effect storms.”

NASA’s satellite image of Ex-Tropical Cyclone Kelvin, moving through Western Australia on Feb. 20, 2018

Small Florida insurers survive hurricanes and “Judicial Hellhole”

Florida’s small P/C insurers have withstood losses from Hurricane Irma and a legal environment that’s dubbed a “judicial hellhole” by the American Tort Reform Association, a recent article in S&P Global Market Intelligence reports.

The financial ratings firm Demotech affirmed the financial strength of over 50 companies in late March, a decision found “encouraging” by the CEO of the state-run Citizens Property Insurance Corp, Barry Gilway.

Gilway said that Demotech’s March actions is evidence of the resilience that smaller carriers showed during a year in which Hurricane Irma caused insured losses of about $8.61 billion, according to the latest Florida Office of Insurance Regulation tally.

Florida insurers face both weather-related risk and costs stemming from litigation on non-weather-related water-loss claims with an assignment of benefits (AOB) and other legal matters.  To combat the AOB problem, Citizens has drawn-up changes in policy language, increased efforts to fight fraud and grew its managed repair program. In January, Citizens said it expects AOB and litigation costs would account for about 23 percent of its 2018 operating expenses, up from 16 percent in 2017 – an increase of $17 million.

The frequency and severity of water-loss claims over the past 2.5 years shows “extremely negative trends,” and that deteriorating trends have begun to spread northward within the state, said Gilway.

Citizens is reopening approximately 37 percent of claims related to Hurricane Irma as part of its ongoing work to help its policyholders, who have been frustrated by a shortage of contractors, the Insurance Journal reported. A spokesperson for Citizens said that it’s common for claims to be reopened, and that the majority of those reopened are non-AOB Irma claims.

2018 Atlantic Hurricane Forecast

On Thursday April 5th Philip J. Klotzbach and Michael M. Bell, scientists with the Colorado State University, issued their 2018 Atlantic Hurricane Forecast.  The forecast anticipates slightly above-average activity for the 2018 Atlantic basin hurricane season.

There is slightly above-average probability of a major hurricanes making landfall along the continental United States coastline and in the Caribbean.

Klotzbach and Bell estimate that 2018 will have 7 hurricanes (median is 6.5), 14 named storms (median is 12.0), 70 named storm days (median is 60.1), 30 hurricane days (median is 21.3), 3 major (Category 3-4-5) hurricane (median is 2.0) and 7 major hurricane days (median is 3.9). The probability of U.S. major hurricane landfall is estimated to be about 120 percent of the long-period average.

Probabilities for at least one major hurricane landfall on each of the following coastal areas:

  • Entire continental U.S. coastline – 63% (average for last century is 52%)
  • U.S. East Coast Including Peninsula Florida – 39% (average for last century is 31%)
  • Gulf Coast from the Florida Panhandle westward to Brownsville – 38% (average for last century is 30%)

As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them. They should prepare the same for every season, regardless of how much activity is predicted.

Click here for the full forecast.

Dr. Philip Klotzbach is a non-resident scholar for the Insurance Information Institute (I.I.I.)

2017 sets record for highest insured disaster losses

Munich Re has released its 2017 catastrophe review, and disaster related insured losses for the year are the highest on record at $135 billion.

The record losses are driven by the costliest hurricane season ever in the United States and widespread flooding in South Asia. Overall losses, including uninsured damage, came to $330 billion.

The United States made up about 50 percent of global insured losses in 2017, compared with just over 30 percent on average. Hurricane Harvey, which made landfall in Texas in August, was the costliest natural disaster of 2017, causing losses of $85 billion. Together with Hurricanes Irma and Maria, the 2017 hurricane season caused the most damage ever, with losses reaching $215 billion.

The United States also suffered a devastating wildfire season and at least five severe thunderstorms across the country, accompanied by tornadoes and hail.

Mark Bove, a senior research meteorologist at Munich Re, said in a New York Times interview that losses jumped in the United States because so many of the disasters hit highly populated areas: the Houston bay area, South Florida, Puerto Rico. It’s a trend that he expects to continue.

The I.I.I. has data on natural disasters here.

The Week in a Minute, 11/30/17

The III’s Michael Barry briefs our membership every week on key insurance related stories. Here are some highlights. 

 The I.I.I.’s James Lynch participated in Property Casualty Insurers Association of America’s Thursday, Nov. 30, satellite media tour on the dangers of marijuana-impaired drivers as states liberalize their marijuana laws.

The 2017 Atlantic hurricane season was the first one ever to feature three Category 4 storms making landfall on the U.S. mainland (Harvey in Texas, Irma in Florida) as well as a U.S. territory (Maria in Puerto Rick).

Twelve of 14 post-Hurricane Irma fatalities at The Rehabilitation Center of Hollywood Hills (Broward County) were deemed by the coroner to have been “homicides due to heat exposure.”

 

2017 Atlantic Hurricane Season in Review: One for the Record Books

By Philip J. Klotzbach, Ph.D.

The 2017 Atlantic hurricane season, which officially ends on November 30, has been extraordinary by any standard, with a total of 17 named storms, including 10 hurricanes—six of which were classified as major, storms, measuring Category 3-5 on the Saffir-Simpson Wind Scale.  Historically, 2017 ranked as a top-ten year in most widely recognized tropical cyclone (TC) metrics (Figure 1).

Figure 1: 2017 Atlantic tropical cyclone statistics compared with the 1981-2010 average as well as its rank compared with all historical Atlantic hurricane seasons since 1851.

What really distinguished the 2017 Atlantic hurricane season, however was the month of September (Figure 2).  All other months of 2017’s hurricane season had near-normal activity, while September broke the Atlantic calendar month record for named storm days, hurricane days, major hurricane days and Accumulated Cyclone Energy (ACE). (ACE is an integrated metric that takes into account the frequency, intensity and duration of storms.)

Figure 2: Atlantic ACE by month in 2017 compared with the 1981-2010 average. 

Atmospheric and oceanic conditions were conducive for an active season and this was especially true during September.  During the period from late August to late September when the season was most active, the tropical Atlantic had very low vertical wind shear (Figure 3).  Vertical wind shear is the change in wind direction with height in the atmosphere.  Strong vertical wind shear tilts the hurricane vortex, disrupting the circulation and preventing the pressure fall necessary to sustain a strong hurricane.  Sea surface temperatures were also much warmer than normal, providing more fuel for developing tropical cyclones (Figure 4).

Figure 3:  Vertical wind shear anomalies from late August to late September.  Blue colors indicate reduced vertical wind shear.  Reduced vertical wind shear dominated most of the tropical Atlantic into the eastern and central Caribbean.

 

Figure 4: Sea surface temperature anomalies across the tropical Pacific and Atlantic near the peak of the Atlantic hurricane season.  (The tropical Atlantic and Caribbean were much warmer than normal in 2017.)

Three of the 17 storms that formed in 2017 accounted for the lion’s share of damage.  Hurricane Harvey made landfall in central Texas as a Category 4 hurricane, then stalled near Houston, inundating the metropolitan area with record-setting rainfall.  Hurricane Irma cut a path of destruction across the Caribbean and tropical Atlantic, devastating several islands before becoming the first Category 5 hurricane to make landfall in Cuba since 1924 (Figure 5).  Irma then made landfall on the Florida Keys as a Category 4 hurricane.  Hurricane Maria became the first Category 5 hurricane on record to make landfall in Dominica, then it buffeted the US Virgin Islands before slamming into Puerto Rico as a Category 4 hurricane.  Maria was the strongest hurricane to make landfall in Puerto Rico since 1928.  While the final damage estimates are still being tallied, this season will certainly go down as one of the most devastating Atlantic hurricane seasons of all time.

Figure 5: Satellite imagery of Hurricane Irma as it pummeled the northern coast of Cuba.

Philip J. Klotzbach, Ph.D. is Research Scientist, Department of Atmospheric Science, Colorado State University and an I.I.I. Nonresident Scholar. You can follow him on Twitter at @PhilKlotzbach

Superstorm Sandy

By Phil Klotzbach, lead author of the Colorado State University (CSU) hurricane forecasting team, and I.I.I. non-resident scholar.

Five years ago this month (October 29), Superstorm (hurricane until a few hours before landfall) Sandy made landfall along the coast of New Jersey just northeast of Atlantic City.  Sandy was one of the most devastating hurricanes to hit the northeast United States, causing more than 70 fatalities and $50 billion dollars in damage. It was the deadliest Northeast United States hurricane since Agnes (1972) and the 2nd most expensive United States hurricane on record behind Katrina (2005).  While heavy rainfall and strong winds were part of Sandy’s legacy, the primary cause of the massive destruction and damage that occurred was due to high storm surge levels.

Sandy developed in the SW Caribbean on October 22 (Figure 1). This region is a typical hotbed for October Atlantic hurricanes.  The system slowly intensified, eventually reaching hurricane strength before hitting Jamaica as a Category 1 hurricane.  It briefly reached major hurricane strength (Category 3+ on the Saffir-Simpson Wind Scale) before making landfall in Cuba.

Figure 1: Track of Hurricane Sandy from its formation in the SW Caribbean until its dissipation in the northeast United States.  Figure courtesy of National Hurricane Center.

Landfall in Cuba weakened Sandy somewhat, and the system began to undergo structural changes as it interacted with a large upper-level low pressure area.  This upper-level low caused the inner core to lose intensity, but it also caused the storm to grow considerably in size.  Sandy weakened to a tropical storm, but then vertical wind shear (the change in wind direction with height in the atmosphere), began to abate and Sandy was able to re-intensify to hurricane strength.  The storm, however, retained its large, sprawling circulation. (Figure 2).  Tropical storm-force winds extended more than 900 miles away from the center of the circulation as it approached the United States coast, making it the largest Atlantic hurricane on record (since 1988).

Figure 2: Infrared satellite imagery of Hurricane Sandy on October 29 showing the large, sprawling nature of its circulation.  Figure courtesy of NOAA.

A large blocking high to the north of Sandy caused the storm to track to the northwest (Figure 3).  Once Sandy had finished transiting the warm waters of the Gulf Stream and moved over cooler shelf waters near the New Jersey coast, it completed its transition into a post-tropical cyclone several hours before landfall.

Figure 3: Mid-level weather pattern causing the anomalous track that Hurricane Sandy took.  Strong high pressure to the north of Sandy prevented recurvature and caused Sandy to track towards the northwest.  Figure courtesy of National Hurricane Center.

While the maximum intensity at the time of its New Jersey landfall was 80 mph – equivalent to a Category 1 hurricane – the storm’s large size triggered huge amounts of storm surge.  In addition, tides were running higher than normal, due to the lunar cycle; storm tide values shattered records in parts of New York City.  At the Battery, Manhattan’s southernmost tip, the storm tide exceeded 14 feet, which was more than four feet higher than the previous record set during a winter storm in December 1992.   Many other areas along the coast of New Jersey and in New York City reported storm surge levels of 5-8 feet from Sandy which combined with astronomical factors to cause massive inundation.

Sandy’s transition from hurricane to post-tropical cyclone immediately prior to landfall as well as the massive size of the system has helped us to refocus efforts in the five years since the storm to clearly delineate between the Saffir-Simpson Wind Scale category and potential impacts that the storm may generate. Just because a system transitions from a hurricane into a post-tropical system does not mean that its impacts have been ameliorated. While it has now been five years since Sandy’s landfall, it will forever be remembered in the northeast United States as an incredibly damaging storm.