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BMS Tropical Update August 30th – 9 am CDT

There has been no significant change since yesterday to the overall favorable environment for further intensification between now and Sunday. Moisture availability will steadily increase, shear will remain in the range that may help ventilate a hurricane, and ocean heat content is robust along the full track and highest in the Gulf Stream waters that Dorian will encounter just prior to expected landfall. However, if Dorian slows, this might create some upwelling and weaken the hurricane. This is still uncertain.

When I give talks about weather trends, I often lead with a slide that suggests our weather memories are very short. When I look at the forecast for Dorian, I see a bit of déjà vu in how similar this forecast is to the evolution that occurred with Hurricane Florence last year. Remember, initially, the forecast for Florence was for a more rapid track with major hurricane status at landfall. But, the forecast models later reflected Florence stalling along the Carolina coastline with a bit of a west-southwest component of motion. Not only did the track have a notable change, but this slowing also caused Florence to weaken just prior to landfall, likely due to upwelling of colder ocean water. Whether or not this could happen with Dorian is a big question. Right now the NHC is not forecasting a weakening at landfall, but until 24 hours before Florence made landfall there was no sign of weakening either. At this point, the insurance industry should prepare for Dorian to make landfall as a major hurricane, as this is what the best model guidance and forecasts are indicating at this time.

The Gulf Stream and ocean heat content off the Florida coast is impressive. Source Weathermodels.com

Similarly to Hurricane Florence last year, there is still a considerable amount of track uncertainty in both the direction and the forward speed of the storm which, again, could impact the intensity. Over the next few days, Dorian will continue to track northwest, but will begin to arc westward later today as it moves north of an upper-level low near Cuba and the Bermuda high strengthens and expands to Dorian’s north. Models are in agreement on the timing of the turn west or, depending on some models, even west-southwest. What happens later tomorrow is still uncertain as the models disagree on how far west Dorian will track and at what forward speed.

The ECMWF ensembles remains highly contentious in large part due to dramatic differences in Dorian’s forward motion across models and ensemble suites. For example, in just 48 hours, the spread across the last night’s run of the ECMWF is a whopping 300 miles! Source

If you have been watching the NHC forecast, which, as I pointed out yesterday, is one of the best to review, the track speed and timing of landfall has been slowing. Earlier in the week, landfall was expected to be Sunday – now it’s Monday night. Slow moving named storms often precede erratic behavior or sharp turns, so what this trend in the NHC track really means is increased forecast uncertainty. There is still a chance that Dorian may stay offshore, similar to Hurricane Matthew in 2016. I am a bit doubtful of this, however, given that climatology and weather models typically seem to forecast the western Atlantic high pressure as weaker than it really is. The majority of forecasts have Dorian making landfall as a Category 3 or 4 hurricane near Palm Beach, Martin or Saint Lucie counties. This would put Dorian in a similar landfall area to Hurricane Jeanne, which made landfall as a Category 3 hurricane in 2004 and, today, would cause about $8B in insurance loss.

All the impacts below are all dependent on the track and intensity.

Wind Impacts
When analyzing wind impact, it is important to understand the design of typical structures across Florida to withstand high wind speeds. The following is a great online interactive map. It should be noted that older structures would have slightly different wind speed thresholds depending on the era, but generally, the trend would be similar to what is shown below.

Design wind speeds in the Keys (Monroe County) are also 180 mph vs 130-170 mph along the east coast of FL. Source: https://asce7hazardtool.online/
BMS iVision allows clients to run risks to better understand various impacts from Dorian. This is the newest 3-sec wind speed gust in MPH from Verisk Weather Solutions. There will be some adjustment to this wind swath as the forecast evolves.

Flood Impacts
The trend towards slower motion near or over Florida compounds flooding potential for the state. Dorian’s forecasted landfall intensity is capable of producing structural wind damage and life-threatening coastal surge, but the rising possibility of the hurricane traveling along or up the peninsula at 5-10 mph means widespread rainfall totals of 10 inches or more, especially north and east of the center track. This may be a major issue for the insurance industry.

This is the rainfall forecast which is highly dependent on the forecasted track of Dorian. Source: https://www.wpc.ncep.noaa.gov/qpf/day1-7.shtml

The American Community Survey (2011-2015), estimates that 26% of Florida residents live in the combined 100-year and 500-year flood plains, as indicated by NFIP. The risk of damage from floodwater is real and growing in a large percentage of the U.S. and even more so in Florida.

The private residential market has grown quite rapidly in Florida, too. There are more private flood carriers active in Florida than in any other state. As of July 2018, there were 29 admitted insurers offering primary residential flood insurance in the state, up from 20 in December 2017, and 16 in December 2016. There are also many managing general agencies (MGAs) in Florida that offer flood coverage.

In fact, according to a recent Wharton Risk Management flood market study, there are more than 58,000 private primary residential flood policies across Florida. With that total, there are more private residential flood policies in Florida than there are NFIP policies in 35 different states, including Alabama, Pennsylvania, Illinois, and Washington.

The image above shows the number of private policies by county in Florida.

Given the current forecast of Dorian, this could be the first real test of the residential flood insurance market.

The forecast is suggesting increased confidence that a Florida landfall will be perpendicular to the coastline. This aspect will be important in relation to the storm surge and may result in higher wind impact inland. However, the overall track will determine the wind.

There is a high likelihood that the impact of Dorian will be felt along the entire East Coast, but will be drawn out over the next week as Dorian slowly gets pulled away from Florida into the mid-latitudes. This will increase the insured loss chances of states outside of Florida. A few additional things to consider as Dorian approaches the Florida Coastline:

  1. Soil moisture is already high across much of the state, which could increase tree fall and power outages.
  2. With a new Super Moon occurring today, current tides will be running higher than normal, which could increase coastal flooding and any intensify aspects of storm surge that might occur.
  3. With Dorian potentially making landfall over a holiday weekend, the amount of lost revenue from hotel and restaurants has the potential to be higher, which could increase business interruption in some cases.

BMS Tropical Update 8/29/2019 – 9 AM CDT

Forecast Uncertainty and Verification

Let’s for a minute take a step back and think about when Dorian first became a tropical storm 725 miles southeast of Barbados.  At that time the long-range five-day forecast from the National Hurricane Center (NHC) suggested Dorian would track over the Dominican Republic.  As the NHC forecast advisories were issued, the forecast kept shifting north and east.  As we know now, not only did Dorian miss the island of Hispaniola, but it missed Puerto Rico to the east and will now completely miss the southern Bahamas as well.  When retrospectively looking back from when Dorian first became a tropical storm, its final track position was still within the far upper right part of the cone of uncertainty.

Shown above is the NHC forecast from forecast advisory number two. A red dot has been placed on the map illustrating the verified forecast position which was in error of 109 miles northeast of the forecasted location on the 96 hours forecast.

Over the last several days, the intensity forecasts issued by the NHC have been constantly revised upward and are only now starting to level off in intensity as a category 3 hurricane as Dorian approaches the Florida East Coast.

Tools To Help With Forecast Uncertainty

Because there seems to be a wealth of information flowing around Dorian, I want to share some publicly available tools to help determine what may be the best forecast models to help the insurance industry best narrow down the potential impacts from Dorian.

First, the NHC is historically one of the hardest forecast beat in both forecast track and intensity.  The average track error from past storms makes up the cone of uncertainty they provide.

Second, with so many weather models in existence, it can become quite difficult to select which one to use. It seems each large government has its own forecasting model. There are also universities that run their own models and in some cases private companies run their own models as well (the latter is what Verisk Weather Solutions does, and what is used in our BMS iVision product which offers clients another view they might not be able to obtain from public sources).  Even some reinsurance companies have at times run their own weather models, so there is no shortage of named storm track and intensity guidance. 

BMS iVision allows clients to run risks to better understand various impacts from Dorian. This is the newest 3 sec wind speed gust in MPH from Verisk Weather Solutions. There will be some adjustment to this wind swath as the forecast evolves.

All of these models offer up different paths and intensity forecasts which really adds to the overall uncertainty in an overall named storm forecast.   Historically the European Center for Medium-Range Weather Forecast (ECMWF) has been one of the better long-range forecast models in terms of accuracy.

Third, some of these models actually run ensembles which are formed by taking slightly different initial conditions and/or model physics and integrating each of these ensemble members to generate a spread of possible outcomes.  Since the atmosphere is a chaotic system, small initial differences can have profound impacts on the tracks and intensities of tropical cyclones at a future time.  These differences will result in different model results. The ECMWF runs an ensemble that has 51 different members.  That is a lot of different forecasts from just one model; therefore when using an ensemble it is best to pick the model consensus.  

Fourth, Brian Tang, an associate professor of atmospheric science at the University at Albany, has developed some tools to help limit the uncertainty in named storm forecast by looking at model forecast skill in real-time.   Professor Tang looks at various forecast lead times for forecast intensity and tracks.  The tools may be found here.

Currently, forecast intensity bias over all forecast time periods is suggesting the OFCL (the NHC official forecast) has the least amount of error, and for the 96 hour forecast period the LGEM model (the SHIPS Logistic Growth Equation [LGE] forecast model) shows the lowest intensity error. The number above each column is the number of forecasts used in the calculation. Use this graph to track which model might be preforming the best for forecasted intensity. For a key as to the acronym of each of the models shown use the following source.
Similar to the intensity bias, the track error may also be calculated. Currently, the forecast track error over all forecast times is suggesting the COTC model (the Naval Research Laboratory COMPS-TC model) has the best track skill. The UKX (the UK Meteorology Office model) is also doing well but does not have as many validated forecasts as indicated by the number above each bar. Again, the OFCL NHC forecast is also one of the better-performing forecasts at 96 hours.

Dorian Impacts

It is still too early to determine all of the impacts of Dorian.  As highlighted yesterday, there are some things to think about that are already known factors: 

  1. The forecast is suggesting an increased confidence that a Florida landfall will be perpendicular to the coastline.  This notion will be important in relation to the storm surge impacts and may result in higher inland wind impacts; however, it could perhaps result in an overall narrower area of impact to the insurance industry if the storm crosses the Florida peninsula.
  2. There is a chance the storm stalls over Florida, or moves much slower, which could enhance the wind and flooding aspects of Dorian.
  3. Soil moisture is already high across much of the state which could increase tree fall and power outages.
  4. With a new Super Moon occurring on August 30th, current tides will be running higher than normal which could increase coastal flooding and increase aspects of any storm surge that might occur.
  5. With Dorian potentially making landfall over a holiday weekend, the amount of lost revenue from hotel and restaurants has the potential to be higher, which could increase business interruption in some cases.

All Eyes On Dorian As The Holiday Weekend Approaches

With the peak of hurricane season just 12 days away, the tropical Atlantic is awakening right on cue. As we received the final advisory on Tropical Storm Chantal in the North Atlantic a few days ago, Tropical Storm Dorian was taking shape roughly 1,500 miles to the south in the deep tropics. Dorian is currently the only tropical system that should be of concern to the North American insurance industry, as recently named Tropical Storm Erin will be short-lived off the eastern coast of the U.S. and have minimal impact on the Canadian Maritimes.

The Bottom Line
The forecast models for Dorian are now showing Dorian will intensify as it travels east of the Bahamas. This is due to a much better environment which contains less dry air, lower wind shear, and warmer sea surface temperatures. The insurance industry should anticipate a stronger storm east of the Bahamas, as well as the possibility of Dorian making a Florida landfall as a major hurricane. However, it should be noted that the uncertainty in the forecast at this time is high with a mixed bag of possible outcomes, ranging from a weaker category 1 east of Bahamas to a major hurricane. While uncertainty is high, wind and rain impacts are possible in Florida later this weekend.

Dorian Forecast Details
In its long trek across the Atlantic, Dorian hasn’t been able to strengthen much because of dry air intrusion. Dorian has featured pulses of convection from time to time, but that convection hasn’t really been able to surround the center of the storm. Although Dorian will be passing over very warm water, the dry environment and a bit of wind shear could keep it in check over the next 48 hours.

There are several variables that will determine Dorian’s fate, but it seems that there are two critical periods. The first will be Wednesday night when Dorian will be in the vicinity of Puerto Rico. If Dorian passes over too much of Puerto Rico, it will interact with high mountains that could rip it apart. Restrengthening will take more time. However, if it just skims Puerto Rico, it has a better chance for survival downstream and will take less time to restrengthen.

The next critical period, sometime around Friday night, will be when Dorian moves into an environment which is more favorable for development as Dorian gets steered towards the east coast of Florida around an upper-level ridge. Some models indicate that there will be a broad upper-level trough to the west. Whether or not that hinders Dorian’s intensity with increased wind shear is a big source of uncertainty at this time and one of the only factors limiting the intensity forecast.

It’s really too early to be confident about a track forecast, so the current forecast by the National Hurricane Center is as good as any. That being said, the “cone of uncertainty” is over 400 miles wide at 120 hours, which is roughly the forecasted lead time for a potential Florida landfall. Also, the distance from Jacksonville to Miami is 347 miles, so a large section of the Florida coastline could potentially experience Dorian.

At this time it is not advised to focus on the NHC center track line. The cone is the track and the cone at this point is 400 miles wide. At this time it is too early to say where Dorain will make landfall, but Florida has the highest probability at this time.

Intensity forecasts are tricky, and it’s much too early to speculate. Dorian could be an anywhere from a weak category 1 hurricane, with just heavy rain and minimal wind threat, up to a major hurricane. However, with the warm sea surface temperatures over the Bahamas and lower wind shear, a stronger storm should be expected and the trend in intensity forecasts over the last 12 hours suggests this.

Yesterday much of the insurance industry was thinking a tropical storm as Dorian tracked into the Bahamas. In the last 12 hours, the trend is for a much stronger storm. No reasons why a major hurricane couldn’t also be in the future forecasts, a weaker storm is unlikely as Dorain tracks into the eastern Bahamas over the next 48 hours.

Things To Consider At This Time
Although a Florida landfall has the highest probability (65%), the angle of landfall can make a big difference in impact. The angle will impact everything from storm surge to the wind along the coastline. Although much of Florida recently saw some sort of impact from Hurricanes Michael and Irma, not all areas experienced high winds. The angle of these high winds can create different outcomes, which is why the angle of impact is important. Of course, this will all depend on the strength of Dorian at landfall, which is unknown at this time.

Soil moisture could also be a factor. Coastal locations south of Cape Canaveral have been fairly wet, while points to the north have been dry over the last 30 days. We could see increased treefall if the higher winds occur where the soil is saturated, but the rainfall could actually be welcome news for points to the north.

With a new Super Moon occurring on August 30th, current tides will be running higher than normal which could increase coastal flooding and increase aspects of any storm surge that might occur.

With Dorian potentially making landfall over a holiday weekend, the amount of lost revenue from hotel and restaurants has the potential to be higher, which could increase business interruption in some cases.

Wildfire Outlook and Future Problem Areas – August, 2019

While the global insurance industry seems to be eyeing every cloud mass in the Atlantic Ocean for the development of the next possible named storm and what might unfold in terms of overall activity and landfalls, the industry should also pay attention to a different type of weather forecast. Some similarities can be drawn between the lower 48-state fire season and the Atlantic hurricane season in that they are both off to fairly quiet starts. There is curiosity within the industry as to whether the back half of both of these seasons will be hyperactive.

With a total of over $33B of North American wildfire insured loss since 2016, it’s clear that wildfire has taken on new importance in the insurance industry. The good news is that much of North America is exiting the core of the fire season and, so far this summer, there has been a welcome wildfire reprieve. In California, only 24,579 acres have burned this year as opposed to 621,784 acres last year (CAL FIRE Only stats to Aug 22). The other bit of good news is that California has only about 6.73% of the state under abnormally dry conditions, with no drought conditions being reported. This is a vast improvement from one year ago when 47.19% of the state was reporting drought conditions.

California Department of Forestry and Fire Protection (CAL FIRE) combined Statistics including the U.S. Forest Service for the state of California.

There is still much of the fire season remaining, including the most dangerous time of year when strong, dry offshore winds peak during the months of September, October and November and have, historically, been associated with the majority of California’s worst fires. The Santa Ana and Diablo winds which, when combined with abundant fine fuels, can lead to elevated fire activity, even if the current fire risk is low. In fact, after a fairly wet winter, the abundance of fine fuels, such as annual grasses, has increased, which adds to the fuel load across the region. As these fuels dry out, there is significant risk if a fire starts and high winds are present.

The National Interagency Fire Center is one of the official sources for wildfire assessments and outlooks. According to its forecast, the areas of greatest concern continue to be the lower and middle elevations across California, the northern and western Great Basin, and portions of the Pacific Northwest where the robust grass crop has cured and can become an easy source of fire.

Since the halfway point of the western wildfire season has passed, there are some signals that point towards an active, compressed, season across the west as the southwestern monsoon becomes more active. While this will effectively end the fire season across the southwest, lightning-induced fire activity is expected to increase elsewhere. And, since humans cause the majority of wildfires, risk is always present. When accidentally or intentionally set fires are combined with wind events, which have been largely absent thus far, but will intensify in frequency by mid to late month as dry frontal passages become more common, the risk of wildfire will also increase. Wind events and low humidity will contribute to a likely increase in fire occurrences into the start of November.

During the late fall or even early winter, when a high-pressure system forms over the deserts of the Great Basin, the high pressure circulates clockwise, pushing air westward toward the lower-pressure areas of the coast, where it drops from high elevation to sea level. This causes the air to become compressed and it heats up, and its relative humidity drops. As the air drops from high elevation to sea level it can be forced through passes and canyons. This can cause wind gusts of 40 to 60 mph or even stronger. Image Source: InsideClimateNews

Unlike a hurricane, which often provides the insurance industry with a few days’ notice to determine expected loss, devastating fires often occur at a moment’s notice. The best thing the insurance industry can do is practice good accumulation management now, acknowledging areas that could become the next Paradise, California. Recent work by Pamela Ren Larson and Dennis Wagner at azcentral.com concluded that there are as many as 526 locations with a higher wildfire potential than Paradise, CA. In the absence of a newer, sophisticated catastrophe model, the insurance industry can still use Larson and Wagner’s very thoughtful analysis to determine the overall risk to a portfolio via a simple risk score. Although their analysis looked at the hazard, it also tried to understand the overall human risk, which life and casualty lines should contemplate.

The insurance industry may also want to consider analyzing areas outside of the western U.S. that could become the next Gatlinburg, Tennessee. For example, the 1.1 million acres of Pine Barrens in New Jersey, which is mostly rural despite the proximity to the sprawling metropolitan cities of Philadelphia and New York City, could result in a major insurance industry loss. There are vulnerable locations along the wildland-urban interface where fires are common. At some point, the weather conditions will be right to create a worst-case scenario, which could impact towns like Tabernacle or Barnegat Township in New Jersey. Thankfully, the peak of the wildfire season in New Jersey is during the spring months.

General Wildfire Risk Hazard Across the State of New Jersey. Source: Rolling Stone Will-Americas worst Wildfire Disaster Happen In New Jersey

Another recent concern is the increased wildfire risk that has been created by Hurricane Michael across Georgia and the Florida Panhandle. According to the National Association of State Foresters, a total of 92 million tons of timber, or roughly 4 million truckloads of timber, were destroyed by Michael’s fierce winds. The volume of dead and downed fuels will likely contribute to an increase in the number, intensity, and duration of wildfires over the next three to ten years. According to the Association, there are typically 4.87 tons per acre of available fuel in Florida. Currently, the average is up to 58 tons per acre – a ten-fold increase. In a catastrophic area, there are over 100 tons per acre. In fact, analysis done by the Southern Wildfire Risk Assessment Portal puts 49 communities at risk in the catastrophic wildfire zone and 194 communities at risk in the severe wildfire zone. Again, much like New Jersey, the highest likelihood of wildfire across this region is in the spring.

While the wildfire season will likely end up being below normal in terms of acres burned for the western U.S., it only takes one fire under the right conditions to make a memorable season. Significant wildfires can occur even when fire conditions are not extreme. Therefore, it is beneficial to understand wildfire risk accumulation and determine what is a comfortable level of loss by simple aggregation analysis or using new sophisticated wildfire models. These models have suggested that recent wildfire seasons are on the order of a 30 to 60-year return period, so none of the recent U.S. wildfires are considered tail events. Instead, these events have low return periods of less than 100 years, which reflects increasing U.S. wildfire risk in large part due to development of the wildland-urban interface. Insurance companies should understand this risk due to the proliferation of wildfire-prone areas throughout the U.S.

BMS Tropical Update – August 13th

It’s been a while since the last BMS Tropical Update on July 11. That update focused on Tropical Storm Barry, which eventually made landfall along the central Louisiana coastline as a minimal Category 1 hurricane. Even though it was a disheveled mess of a storm, it still caused nearly $100 million of insurance industry loss in Louisiana and set an Arkansas state rainfall record of 14.58” near Murfreesboro, Arkansas. Luckily, this large amount of rain did not fall along the Mississippi River in southern Louisiana, which was at already historic high levels along many sections, including levy-protected New Orleans. With Barry’s landfall, it joined 12 other July hurricane landfalls in the Gulf of Mexico since 1900. However, as we look forward to the remaining months of the hurricane season, it’s worth noting that there is no correlation between hurricane activity occurring before August and how much activity will be seen during the remainder of the season.

By now you may have seen the various updated Atlantic hurricane season forecasts, which, for the most part, continue to call for above-normal activity. As I have stated several times, the overall number is not what is important, but, rather, the steering currents that influence the track(s). Contrary to popular belief, however, most named storms have fairly regular and well-defined tracks because of the location and orientation of the Bermuda Azores high pressure, which ultimately determines the tracks of most named storms. The difficulty in predicting a storm track occurs either when the typical climatological steering wind flow is replaced by a less common, large-scale flow or, even more importantly, when rapid changes occur in the strength and orientation of the steering current, such as a bypassing mid-latitude trough, which is really only well-forecasted 5 to 7 days in advance.

Above is the current steering flow across the Atlantic Ocean. Note the current weakness across the Bermuda Triangle. Absent any mid-latitude system, this would likely be the path for named storms out of the deep tropics.

The average date for the formation of the season’s third named storm is August 13, and the average date for the second hurricane is August 28, so there is nothing unusual about having a calm spell this time of year like we’ve seen recently. There have been several tropical waves that have propagated from the African coastline, and a few of these have been watched by the National Hurricane Center. Tropical Depression Three, which formed for less than 24 hours off of the eastern coast of Florida, provided a glimpse of where named storms could track this season if the current North American and Atlantic pressure patterns hold into the peak of the hurricane season. However, first let’s determine the factors to consider for the remainder of the hurricane season and then worry about the steering current once the storms begin to form. In the beginning of the season, it was suggested that named storms would form closer to the U.S. coastline rather than in the Main Development Region, and track closer to the eastern coast of the U.S. with the overall season seeing more back half activity.

Although many of the headlines suggest that an above-normal season is yet to come, these headlines should probably be taken with a grain of salt. Take the NOAA forecast, for example. There is a 45% probability of an above-normal season, which obviously means there is a greater chance of a normal to below-normal season at 55%. In fact, I don’t think there is much confidence in the August activity forecasts, even though they are usually the most accurate when it comes to the overall Atlantic Basin activity.

There are a number of reasons why there is a lack of confidence in the forecast:

Unfortunately, even with the more reliable August forecast, there are still a lot of variables for the remainder of the season. Perhaps the best guidance would be to view the analog years, which serve as a guide for potential activity and possible tracks for the remainder of the season.

Above are the various analog years (1991, 2012, 2014, 2015) which may best indicate the current conditions and possible track of storms this season. Depending on the overall timing of development, analyzing these years may provide a guide as to the general track storm could take this season, but the timing of mid-latitude weather systems will determine the steering level winds if they reach the U.S. coastline. Example: Isaac or Sandy 2012 (Remember Sandy could have also turned out to sea)

This week we may see the remnants of an old stalled front off of the eastern coast of the U.S., providing a chance at tropical cyclogenesis closer to home. Hopefully, there won’t be a need for too many BMS Tropical Updates over the next 30 days, will be keeping an eye on how any potential events could impact the insurance industry.

Summary of IBHS Disaster Dynamics Academy – Evaluating Garage Doors as a Damage Amplifier

Most Americans have fallen in love with the automobile, which is why miles of roadways reach across the country and so many residential structures in the U.S. have garages to keep these assets safe and clean. However, garages can become major problems in high wind events. When the doors to these large open spaces fail, it can cause major structural damage.
This past week, I was fortunate enough to attend the Insurance Institute for Business & Home Safety’s (IBHS) fourth Disaster Dynamics Academy session – Inside the Eye: Defending Homes Against Hurricane Damage. In this BMS Insight, I will share my experiences and what I learned about garage doors being a damage amplifier.

A Meteorologist’s Dream
Throughout my career, I have read countless papers about hurricanes, helped price and understand various aspects of hurricane risk, examined gigabytes of hurricane wind and claims data, and helped insurance companies recover after the devastation these events can cause. However, growing up and living as far away from an ocean as one can get, I’ve had limited firsthand experience with hurricanes. In fact, my only experience was on September 4, 2010, while living in Halifax, Nova Scotia, Canada, when Category 1 Hurricane Earl raced across the area. Most people wisely took shelter, but I took the more unconventional approach as a meteorologist to experience the hurricane-force winds for myself (as safely as possible). On that day, I headed out to Lawrencetown Coastal Heritage Park beach to experience my first hurricane. It truly gave me a new appreciation for what a hurricane can do and for what the insurance clients I support are facing every year.

This is video taken of my Hurricane Earl experience in Nova Scotia on September 4, 2010.
Driving rain made it hard to get a clear image of me on Lawrencetown Coastal Heritage Park beach, NS, Canada – Category 1 Hurricane Earl

Because I have spent most of my life living in the Upper Midwest, I’ve experienced my share of strong wind events while supporting insurance clients that have had to endure the same damaging windstorms. In fact, I’ve had firsthand experience with some of the research that the IBHS is currently conducting. I recently had a pole barn built on a big open farm field. On June 11, 2017, a strong line of thunderstorms worked their way across the western metro area of Minneapolis. A downburst of wind from these storms blew in the barn door, also causing damage to part of the roof. Luckily, there was no structural damage to the newly constructed barn, but, as a result, our replacement door was upgraded to a reinforced W4 door with a wind rating of 110 mph to prevent another similar incident.

This is the standard garage door that was installed on our pole barn. It was no match for winds of 55 to 70 mph.

Garage Doors Are a Wind Amplifier
During the Disaster Dynamics Academy, the IBHS showcased to its members the steps that can be taken to limit storm damage to various residential and commercial structures. After several years of IBHS demonstrations showing how fortified and non-fortified structures handle hurricane-force winds in its giant wind tunnel, this week they tested garage doors. After all, the garage door is a wind damage amplifier. Garage doors have a large surface area that can be affected by hurricanes and other severe convective winds events, such as downbursts or tornadoes. They are an amplifier because a breach often results in larger structural damage to the roof and walls. However, there are many questions about how this damage occurs, and the IBHS wind tunnel is the perfect place to find answers.
The IBHS conducts scientific research to improve building material performance and construction standards. Recent testing has included asphalt shingle performance research and continuous load path testing. The IBHS has also done extensive field investigation into past hurricanes and strong tornadoes, such as the 2013 Moore tornado, to help understand the various aspects of wind damage. One of the key findings from the garage door field investigation is that roughly 60% of homes had structural roof damage if the garage door was damaged, while roof damage hardly ever occurred if the garage door remained intact. This supports the notion that the garage door is an amplifier of damage.

IBHS Garage Door Testing
In the IBHS wind tunnel garage door testing, they were focused on determining the most appropriate methods and cost-effective practices to ensure that buildings are adequately constructed for the hazards they face. However, the questions around garage doors are complex. The internal pressure may be three times more than the external pressure, resulting in a large pressure difference between the inside and outside of the building. This can lead to major structural failure when the pressure equalizes. Damage that is commonly associated with a failed garage door is the collapse of an adjacent side wall. Some garage door failures may result in the loss of roof decking above the garage, or in extreme cases, the entire garage may collapse. If the garage door fails, it can also lead to a large amount of water entering the building, which can increase damage to contents from wind-driven rain.
The IBHS garage door testing looked at many different types of doors, including the double car door, single car door, twin single-car door, commercial roll-up doors, garage doors with and without automatic openers, and even insulated and non-insulated doors. There are many other variables that needed to be tested to help understand door failure, such as critical wind angles to the door and different wind speeds. The IBHS tested both wind rated doors and non-wind rated doors, as well as the types of hardware used to install the door. One could have a wind rated door, but it may come with normal hardware that could be prone to failure.

This is my raw iPhone video of the test and the resulting damage. The test showed that the door folded in, and the hardware holding the door also failed. Also notice some of the testing of the fabric roofing material letting lose.
This is up close picture of the door damage. Notice the door folded in and the hardware on the lower right also failed. Remember if you install a wind rated door the hardware needs to match.

The Test
I can’t comment on all of the initial testing the IBHS has been conducting, but I can share my experience with the Disaster Dynamics Academy garage door test session. The test involved a normal big box store double garage door without an automatic opener. The standard two stall garage area was equipped with various pressure sensors along the wall and door; after all, the pressure on the walls is critical to what causes the overall failure. As the test began, the IBHS 105 Vaneaxial fan array, each with a 350 horsepower motor, were started at a steady 50 mph and were slowly ramped up every few seconds. As the fans approached hurricane-force levels, you could hear the wind whip around inside the six-story, 21,000 square foot testing area as turbulent winds began to flex the double garage door. As expected, the door folded in and hardware failed at around 90 mph. If it were not for the bracing behind the door to support the array of sensors, the door would have likely folded in completely and been ripped off its rollers and pushed to the back of the two stall garage space. Maybe the most exciting part of the test was the fact that the fortified structure sustained very little damage to category 3 winds, which was expected, as this was a test for doors and not to see the results of building failure. If the IBHS did a building failure test with every door, the testing could take years to complete, which is why the fortified construction is so important. Given the personal experience with my barn, and then seeing first-hand how easily a garage door can fail in the IBHS test facility, I believe there needs to be more attention paid to this wind damage amplifier. Currently, however, there are very few insurance companies that underwrite for such wind variables. What’s even more concerning is that very few areas of the country have building codes requiring wind-rated doors. Hopefully, with the important work that the IBHS is doing, the most appropriate methods and cost-effective practices for garage door construction can be determined. In addition, building codes could be established and existing code standards updated, all from using science in one of the coolest facilities I have ever been in.

This is the IBHS test facility. Behind me are the 105 fans that can create winds as high as a Category 3 hurricane.

BMS Tropical Update July 11th

As mentioned in the last BMS Tropical Update, a storm is brewing in the Gulf of Mexico.  The National Hurricane Center has now named this system Tropical Storm Barry and expects it to potentially become a hurricane by Saturday and make landfall shortly thereafter, with possible impacts along the coasts of Texas and Louisiana, particularly in the city of New Orleans.  As many already know, New Orleans sits below sea level and has had its share of flooding problems in the past.  Since water is the new wind risk for the insurance industry, this BMS Insight will focus on this threat in a bit more detail, as any wind damage at this time is uncertain given the high forecast uncertainty around the overall intensity and track of the storm.

The forecast models are suggesting as much as 18 inches of rain for the region, which isn’t good, considering that the area is already inundated with rain. New Orleans has already flooded this week from rain, with many streets covered with a dangerous amount of water.  The Mississippi River is expected to rise to 19 or 20 feet by the weekend, which is near the height of the city’s levees.

By Saturday, it may have winds of 85 mph, making it a Category 1 hurricane on the Saffir-Simpson wind scale.  It should be noted, however, that there is a lot of uncertainty around the forecasted intensity of the storm. This intensity will depend on how much wind shear the storm encounters and how much time it spends over the warm waters of the Gulf of Mexico.  Currently, the worst-case scenario appears to be a Category 1 hurricane.  However, forecasts can change fast, as we experienced with Michael last year.  Most of the model guidance is suggesting a lopsided tropical storm with a landfall somewhere along the Louisiana coastline.

Wind speed is just one of the insured loss concerns from the storm.  Historically, flooding has not been a big concern for the insurance industry, but the take-up rates of flood insurance are higher in Louisiana, including New Orleans.  The reinsurance markets are taking on some of the risk from the National Flood Insurance Program, so this flood risk needs to be watched.  Also, coastal flooding tends to be the deadliest aspect of a hurricane.

The main concern here is that the storm surge combined with heavy rainfall could reach 3 to 5 feet, which would flood many of the low-lying areas of Louisiana.  This storm is expected to generate a lot of rain, with some areas potentially seeing more than a foot, which can contribute to inland flooding along the banks of rivers.

This is the current National Weather Service rainfall forecast over the next 7 days. This rainfall forecast will depend highly on the track of Barry
Current National Weather Service Forecast river level in New Orleans. This forecast will change with the track and intensity of Barry

The biggest threat from the storm may be in New Orleans, where the Mississippi River is already at 16 feet due to the very wet spring and summer upstream.  Some states along the river have seen their wettest spring in recorded history.  All of this water has worked its way down the Mississippi River, which has been high for well over a month now.  The National Weather Service is now predicting the river to crest at 19 feet on Saturday.  That is one foot below the top of the river levees. This could change given the track of the forecast. This morning the forecasted river height was 20 feet, so the forecast is changing for the better since the newest forecast is now one foot below the top of some of the levees.

So, why is this a concern?  During both Hurricane Katrina in 2005 and Hurricane Isaac in 2012, storm surge pushed well upriver. In those cases, however, the river was only at a level of 3 feet or less.  During Katrina, a Category 3 hurricane with top winds of 125 mph, the river swelled to at least 15.25 feet at the Carrollton Gage in New Orleans.  The gage stopped operating when the water reached that level.  Several barges were deposited on top of the levees in Plaquemines Parish during the storm by surge water.  During Isaac, a Category 1 hurricane with top winds of 80 mph, the river rose to 9.5 feet at the Carrollton Gage.  While the current river level in New Orleans is 16 feet, levees and floodwalls protect the city up to water heights of about 20 feet.

How high is a 20-foot-high river stage for New Orleans?  It is higher than 99.9% of the city’s land surface, higher than every human being except those in multi-story buildings and about 30 feet higher than the lowest neighborhoods.

The red dots show where levees in New Orleans are under 20 feet.  This is where over-topping of levees is most likely if the forecast of 19 feet comes to fruition on Saturday. The red dots on the north side of the Mississippi River flooded during Katrina, including the Lower 9th Ward.
These are the areas of New Orleans that flooded during Katrina.

In summary, the precursor for a bad flooding event is set for New Orleans and remains for much of the hurricane season.  Many areas of Louisiana are flat, and flooding is a big concern with this upcoming storm.  There is uncertainty at this time around the potential strength and track of the storm, which also increases the level of uncertainty around the storm surge that may be expected.  However, the rainfall forecasts have been fairly consistent over the last several days, with most of the heaviest rain expected to fall along with the storm’s forecasted path.

BMS Tropical Update: July 9th

There is an old proverb used to describe the Atlantic hurricane season: “June – too soon; July – stand by; August – come they must; September – remember; October – all over.” In fact, we suggested in our May BMS Tropical Insight that the next best opportunity for tropical storms was going to be in early July. It appears that June was indeed too soon for tropical threats to the U.S. coastline. However, with the start of July, that is expected to change with development appearing likely in the northern Gulf of Mexico later this week and into the weekend.

The NHC is giving an 80% chance of a Tropical depression forming in Gulf of Mexico later this week.


A precursor vorticity center (areas of spin) is currently heading south through Georgia and will emerge into the northeast Gulf of Mexico by Wednesday. This circulation will take advantage of warm water in the area to build thunderstorms and may slowly intensify into a tropical system.
Dry air and dust from a few major outbreaks of Saharan dust have battered most of the Atlantic basin for the last several weeks. This combined with strong wind shear has prevented tropical development across the Atlantic basin since Subtropical Storm Andrea briefly roamed the waters of the west-central Atlantic in late May.

With the Madden-Julian Oscillation (MJO) currently in a positive phase that supports upward motion over Central America, the absence of strong wind shear and warmer than normal waters across the Gulf of Mexico, it should not take much to organize a tropical named storm which, if it develops later this week, will be named Barry. For the last several days, the forecasted steering winds have suggested that any named storm would drift toward the central and western portions of the Gulf of Mexico this weekend. This would give it more time over open water and could potentially create a stronger storm. With this track the risk to the insurance industry grows due to the large amount of exposure in the Houston areas, the risk to offshore assets increases due to a number of petroleum rigs and refineries along the central and western Gulf Coast. Regardless of how much development we see, the forecast models are suggesting multiple days of showers and thunderstorms that could potentially bring flooding to the southern Plains, lower Mississippi Valley and/or the southern Appalachians starting this weekend and into next week, depending on the track and timing of the storm. Some models take the tropical storm as far west as Houston which has no issue flooding from even the smallest of weather systems. Currently, some of the guidance calls for 15″ of rain over the next 7 days for the area.

The overall model guidance from the ECMWF and GFS models have been back and forth over the last few days and the landfall location as suggested by the above GFS ensembles is anywhere from east Texas to Louisiana. Keep in mind this entire area will see a lot of rain.
Source: https://www.tropicaltidbits.com


The last time a named tropical system made landfall in the U.S. during the month of July was Tropical Storm Emily of 2017. Emily formed in the eastern Gulf of Mexico and moved into the central Florida Peninsula on the last day of July, so it’s not unusual to see the forecast of such an event happening this week. As I mentioned in our May BMS Insight, it appears that this season’s tropical activity will be more likely to develop closer to the U.S. coastline instead of out in the Main Development Region (MDR) of the Atlantic Ocean. The bigger question is just how much activity we’ll see this season as we move toward its climatological peak at the beginning of September.


Forecasters continue to call for five to eight hurricanes to develop this season. July still does not look like a very active period for named storm development, as large scale sinking air will continue over much of the Atlantic basin, along with on and off bursts of Saharan dust that may keep activity to a minimum. While El Niño conditions may suppress the total number of tropical storms and hurricanes in the Atlantic basin this season, the data is suggesting that El Niño is weakening and may become a non-factor as we head into September. With the warmest ocean temperatures right along the U.S. coastline, the insurance industry should continue to watch for tropical waves coming off Africa which could potentially strengthen into named storms when they get closer to the U.S. coastline versus the MDR in a more typical season.

Above are the different phases of the MJO and the influence on precipitation. Notice the red circled areas above. Tropical cyclones making landfall along the Gulf Coast during Phase 2 of the MJO during meteorological summer causes a statistically-significant positive precipitation anomaly to show up in the Deep South in the 1979-2008. Research here by Zhou et al.
Notice how the red circled areas match the forecasted areas for heavy rainfall over the next 5-7 days along the Gulf Coast.

We are also now in the period where the insurance industry can begin to watch the subseasonal forecast. I have mentioned before that one of the best ways to predict this is to use the MJO, which is a pulse of upward motion that travels the tropics but also creates areas of sinking stable air in other parts of the tropics. This symbiotic pattern of wetter and drier areas moves east as a unit and typically completes a full cycle in 45 to 60 days. When the MJO (or similar phenomena) promotes upward motion over the Atlantic, hurricane development and rapid strengthening becomes much more common. According to research performed by Phil Klotzbach of Colorado State University, hurricane damage in the U.S. during convectively active phases of the MJO since the early 1900s is nearly three times greater than during suppressed Atlantic phases.


Therefore, I believe the next round of tropical storms may begin during the second week of August. Based on the current state of African waves and favorable conditions for development along the U.S. coastline, we may also be seeing an active late September and early October. Until then, keep watching the skies off the Gulf Coast and along the southeastern U.S. for the development of named storms that might not coincide with the MJO phases.

Insurance industry impacts to upgrading Michael to a Category 5

When Hurricane Michael made landfall on October 11th 2018, it had a central pressure of 919mb, which is the third lowest pressure of any U.S. landfalling hurricane. Yet, at the time, the storm was classified on the Saffir Simpson Hurricane Scale as a Category 4 hurricane with winds of 155 mph – only one mph below the Category 5 criteria. On April 19, the National Hurricane Center (NHC) announced what some meteorologists were already thinking, that, at the time of landfall, Hurricane Michael was actually a Category 5 storm with a wind speed intensity of 160 mph. The NHC bumped up the maximum wind speed based on a detailed analysis of aircraft, Doppler radar velocities, and new surface wind speed observations. It is worth noting the caveat from the NHC report that the maximum winds were in a very small area and future revisions are possible. Reconstruction of Stepped Frequency Microwave Radiometer (SFMR) winds showed possible higher values, but the reliability is still unknown, and more research is being done on this data.

There is also some other useful information to the insurance industry in the NHC report. Along a wealth of observational data the report also details some important loss information. The National Centers for Environmental Information (NCEI) currently estimates total economic damages from Michael in the United States at $25B. There have been several media articles written about the continuing insurance loss development. With a current insurance industry loss at $10B, the overall figure is coming close to the generally-held rule that the economic loss is about half the insured loss for U.S. landfalling named storms. Another interesting aspect of the report is the overall damage figures. For example, $3B of loss was on Tyndall Air Force Base near the landfall location. The damage survey suggested that every building at the Base was damaged to some degree. In Mexico Beach, 1,584 out of the 1,692 buildings were damaged with 48% being completely destroyed. The report also goes into damage figure details for Bay County and Gulf County. For example, Marianna, Florida, which is over 50 miles inland, had 1,000 buildings destroyed or with major damage. Seminole County in the Southwest part of Georgia reported 99% of homes were damaged from wind gusts in excess of 100 mph.

Not to be overshadowed, the storm surge section of the report is just as impressive. The storm surge surveys and analysis revealed maximum inundation of 14.7 feet above what is normally dry ground in Mexico Beach, which would also explain much of the damage found in that area.

Top Four Historical Category 5 Hurricanes that have made U.S. Landfall. Plots created using NOAA Historical Hurricane Tracks Tool https://coast.noaa.gov/hurricanes/

The formality of upgrading Michael from a Category 4 to a Category 5 is a big deal. Michael is now tied with the San Felipe Hurricane of 1928 or also known as Okeechobee hurricane as the fourth strongest hurricane to strike the United States (including Puerto Rico) since 1900, behind the Labor Day Hurricane (1935), Camille (1969), and Andrew (1992).
If you believe empirical landfall probabilities, the addition of Michael in the U.S. record since 1900 has increased the probability of a Category 5 storm making landfall from 2.52% to 3.36% or, in terms of a return period, 40 years to 30 years. As respects Florida only, the same calculations went from 1.68% to 2.52% and 60 years to 40 years.

Constantly Changing View of Landfalling Hurricane Risk
So, has the overall risk for the insurance industry increased? How will this new data change the insurance industry’s view of landfalling frequency and severity?

Hurricane risk across the U.S. is understood through the use of catastrophe risk models that employ stochastic catalogs containing thousands of events, each one with a small impact on model results. There is an ongoing process of recalibration of the stochastic catalogs. This constant reevaluation of current and past storms contributes materially to the development of a rich stochastic set of events informed by the historical record that is adjusted based on history or future forecasts.

Due to advanced observation techniques and improved understanding of tropical cyclones, the Hurricane Research Division (HRD) has implemented a data set (HURDAT2) that addresses errors and biases identified in the historical record. A working group of scientists makes corrections to location and intensity information in the six-hour track points for select tropical cyclones. Additionally, this research, supported by new evidence and data, adds previously undocumented cyclones to the record. Currently, the scientists are looking at storms after 1960 with further changes likely as a result of new findings.

One does not need to look very hard for proof that catastrophe modeling companies use changes in HURDAT2 to help adjust landfall frequencies. Recently, HURDAT2 updated Hurricane King (1950) from a Category 2 to a Category 3 storm resulting in a long-term rate increase in Miami Dade County in one of the stochastic catalogs. Another notable example of a tropical cyclone reanalysis is the Labor Day Hurricane of 1935. Upon reanalysis, the maximum wind speed at the time of its first landfall over the Florida Keys was increased (23 mph), increasing its intensity to strong Category 5 status. This reanalysis revised the Labor Day Hurricane to be the strongest U.S. landfalling hurricane in the historical record. Additional reanalysis upgraded its second landfall, in northern Florida, from Category 1 to Category 2 intensity and shifted its track closer to land. This change also resulted in changes in loss results from the Florida region in particularly using this event as a historical what if scenario.

As Hurricane Michael continues to be examined by researchers, recent activity will also adjust landfall rates. In fact, the most recent updates of HURDAT2 reevaluated landfalling events during the 2015 – 2016 season, including Hurricane Hermine (2016) and Hurricane Matthew (2016), yielding localized loss increases in the landfall areas. Similarly, losses increased in Canada due to changes in landfall categories for some storms during the 1956 – 1960 period as part of the HURDAT2 updates. In areas that didn’t see any new landfalling storms, small decreases in loss across mainland U.S. resulted.

With the knowledge that Hurricane Michael is, in fact, the fourth Category 5 hurricane to make landfall along the U.S. coastline, it will surely change the historical view of risk, particularly in the Eastern Florida Panhandle, which already has a limited historical record of major hurricanes making landfall. Michael is now the strongest hurricane landfall of record in the Florida Panhandle and only the second known Category 5 landfall on the northern Gulf Coast. Additionally, Michael marks the latest in the season a Category 5 hurricane has made landfall in the United States. All of this should be factored into new landfall rate adjustments.

It is too early to determine potential changes to future stochastic catalogs, but these revisions tend to be in the single percentages based previous Atlantic Hurricane model updates. It should also be a reminder, however, that just because the landfall frequency and severity might change for major hurricanes, the insurance industry should not forget storms of lesser intensity can also cause billions of dollars in loss. Any hurricane can cause great devastation.

BMS 2019 Atlantic Hurricane Season Update

The Season Has Begun
There has undoubtedly been a lot of attention given to severe weather across much of the U.S. since the end of April, but in the meantime, the Atlantic hurricane season has arrived. In fact, most people may not have noticed that the Atlantic Basin already had its first named storm (Andrea) of the season. Andrea was a short-lived (less than 24 hours) storm that formed on May 20, about 300 miles south of Bermuda. Andrea became the fifth tropical storm to form before the official start of the Atlantic hurricane season, which did not officially begin until June 1.

Dates of first named storm formation over the past 50 years. The official start of hurricane season is marked by the horizontal green line, and the median date of the first formation is marked by the horizontal dashed black line. The trend over the past 50 years has been for the first named storm to form earlier, with a large spread. There is no correlation between an early start of the season and the season’s overall activity, as discussed here. Source: (Brian McNoldy)

According to the National Hurricane Center, there is a 60% chance of named storm development in the near term in the southern Gulf of Mexico. It’s typical for us to see early season development in this area. At this time, most of the forecast models are bringing tropical weather up into Texas, which will also bring more moisture to the Central Plains where it is surely not needed at this time.

Invest 91 is a tropical disturbance in the southern Gulf of Mexico, which could develop into a named storm as it moves northwest over the coming days. Source: Weathermodels.com

Seasonal Forecasts

I was recently asked: “Does the insurance industry place any weight on seasonal hurricane forecasts?” My quick answer was Yes and No, as it depends.

To elaborate on the Yes part: The insurance industry has always been supportive of seasonal hurricane forecasts by subscribing to private forecasting companies and by funding academic research in these areas. Most companies don’t like surprises and, naturally, being prepared is the logical thing to do for both the reinsurance and insurance industries. However, insurance companies may be more limited in what they can do than reinsurance companies.

The seasonal forecasts can influence the strategic planning of an insurance company by making sure they have adequate claims adjusters in place going into the hurricane season to better serve their customers. Of course, an active hurricane season might require an insurance company to consider service level agreements or loss adjustment expenses and the effects of demand surge that might need to be paid in an active hurricane season. However, since the insurance industry is heavily regulated, companies have little ability to adjust rates for an active or inactive season ahead of time. The reinsurance industry, on the other hand, can be a bit more opportunistic when dealing with seasonal forecasts in terms of planning ahead to provide reinsurance in the secondary market.

To the No side of the answer: Capital requirements for insurance companies are regulated by rating agencies and the insurance commissioners of each state, and do not allow for rate adjustments on a seasonal basis. As part of its strategic planning, an insurance company may want to stress test a portfolio to a certain loss level, as it has the ability to buy more reinsurance during the season if it is uncomfortable with the potential losses that may come from a particular seasonal forecast. The extent of just how much seasonal forecasting plays into each insurance company’s strategic planning is unknown, but generally, insurance companies spend considerable time with strategic planning to understand the potential of losses in any given season, regardless of the Atlantic Basin seasonal activity.

From a business perspective, it’s hard to rely heavily on forecasting when the accuracy of seasonal forecasting is low. Historically, in June seasonal forecasts, the forecasting of activity has not correlated well with actual insurance industry losses. How many times have you heard about 1992’s Hurricane Andrew and how that season was a below normal year? Yet, Andrew happened and was a very big loss for the industry. “It only takes one” will haunt the industry until forecasting gets better.

The readers of my past Atlantic hurricane seasonal forecasts may know that I am all for our industry moving away from simply looking at activity in terms of the number of named storms and hurricanes the Atlantic basin might produce, and rather focus more on what the pattern is suggesting in terms of landfall impacts. This is where we will find the most value, as I describe in more detail below.

Seasonal Forecast and Landfall Threats
The seasonal forecasts we see each year from various sources that provide a number range of expected named storms and hurricanes in the Atlantic Basin are a dime a dozen. There is usually a considerable spread in these forecasts. Currently, there are 19 different forecast groups that have submitted Atlantic seasonal hurricane forecasts to http://seasonalhurricanepredictions.bsc.es/ . The average of these forecasts calls for 6 hurricanes, which is closer to an above normal season.

What do El Niño and La Niña have to do with tropical cyclones? During El Niño, wind shear increases in the Atlantic and we see cooler sea surface temperatures. In La Niña, wind shear decreases and the sea surface temperatures become warmer in the Atlantic, fueling more tropical cyclone activity. Source: NOAACliamte.gov

One of the major factors being considered in many of these forecasts is what the state of El Niño Southern Oscillation (ENSO) may be during the hurricane season. Currently, there is a weak El Niño occurring in the tropical Pacific, and this is forecasted to maintain into the heart of hurricane season. El Niño historically limits named storm development by increasing wind shear across the Caribbean and the Main Development Region. However, not all El Niños are the same, and this El Niño is a Modoki El Niño. This means that the warmest water is found in the central Pacific rather than off the coast of South America. We may see less of an overall impact on Atlantic hurricane season activity with a Modoki El Niño.

General difference between La Niña and  El Niño season.  However, the current El Niño is more of a Modoki El Niño which has less overall impact on the Atlantic hurricane season. Source: NOAA

Another factor to consider, which I think some of the seasonal forecasts may be missing, is that the depth of warm water is shallow and there is actually cooler than normal water beginning to show up at depth, which actually suggests more of a La Niña signature. This could mean that we see very little El Niño impact this hurricane season and instead begin more of a transition to a La Niña weather pattern for 2020.

The image to the left is the  vertical profile of the water temperatures at depth across the Pacific Ocean from South America to Australia as represented by the black line in the image to the right. Note the cold water below the warmer sea surface temperature closer to South American coastline with much of the warmer than normal water in the Central Pacific, which is more of a classic Modoki El Niño signature. Source. NOAA CPC

Sea Surface Temperatures across the Atlantic are currently warmer than usual, which would suggest a more active season. However, we may also want to consider one of the indexes that the insurance industry has looked at for over two decades now. According to Colorado State University, the Atlantic Multidecadal Oscillation (AMO) is currently in a cold phase, which historically would limit named storm activity in a given season, however, SST will be plenty warm enough for named storm development.

The other two factors to watch this Atlantic hurricane season will be Saharan dust and the Madden Julian Oscillation (MJO). Both of these are difficult to predict at seasonal time scales, but understanding the phases of the MJO can help determine when named storm development will occur. The MJO is the major fluctuation in tropical weather on weekly to monthly timescales that comes from pulses of tropical convection over the subcontinent of Asia. The MJO can be characterized as an eastward moving ‘pulse’ of cloud and rainfall near the equator that typically recurs every 30 to 60 day. In fact, the Atlantic basin is currently going into a phase (The MJO is currently in phase 3 and about to enter phase 4) that is not conducive to tropical development. It would appear unlikely that anything of substance develops in the Atlantic Ocean through early July as El Niño and the phase of the MJO limit convection development, which would also limit named storm development.

Overall, it looks like we have the potential for another late blooming season for 2019 with some subtropical development between now and the middle of July, along with a chance for a weak named storm in the Gulf of Mexico this week.

Saharan dust can be an inhibitor of Atlantic Hurricane activity, but it often moves off Africa in waves. In between these breaks of dust, and when combined with the right phase of the MJO, you can find that named storm development has a higher probability of occurring.

Above are the phases of the MJO and the tropical storm tracks that have occurred across the world. Atlantic Ocean is to the far right in the images above.   The MJO can also considerably influence hurricanes in the Gulf of Mexico, Caribbean Sea, and tropical Atlantic. More hurricanes tend to occur in MJO phases 2 and 3 than in phases 6 and 7. Differences in major hurricane numbers and hurricane days in the main development region are a factor of 3. Source: https://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-12-00026.1

As we’ve discussed, there are multiple factors to weigh when trying to predict the timing for named storm development. However, what are the seasonal climate models suggesting in terms of the possible tracks for named storms? As seasonal climate models continue to get better, we can begin to pick up on the overall pressure and precipitation patterns to help determine where storms will track.

The ECMWF Climate model is suggesting higher wind shear across the Caribbean which would limit tropical storm development in this area.  However, a window of lower shear is forecasted for the Atlantic hurricane season from the Bahamas to south of Bermuda.  Source: Ben Noll Weather

 

The CanSIPS  climate forecast model provides an view of where the Bermuda Azores high might be positioned for the Atlantic hurricane season. The lower than normal pressure coming from the model could suggest area of more named storms. Pressure below average near U.S. coast, above average in Main Development Region. Source: TropicalTidbits.com

 

Seasonal climate models are suggesting that above normal precipitation will be occurring this summer off the eastern coast of the U.S. This suggests that this is where the storm track may set up for the season, as storms bring above average rainfall to the eastern coast of the U.S. and the island of Bermuda. Also notice less overall rainfall in the central Atlantic suggesting storms might form closer to the East Coast if they develop. Source: Ben Noll Weather

Summary

I am expecting a more active than normal (Named Storm and Hurricane Storm Counts) Atlantic hurricane season as I think the Modoki El Niño will have less of an overall impact. When one combines this with the warmer than normal SST and weaker than normal wind shear near the East Coast, the conditions should allow for more than normal named storm development. The climate models are suggesting above normal precipitation on the periphery of the west side of the Bermuda high, which could come in the form of named storms during the summer months.  The key to the overall season will be how the MJO and Saharan dust enhance convection, with the next best possible window after this week coming in early July.  How all of this insight will impact the insurance industry is a big question at this point in time, but risks along the East Coast need to be watched.