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BMS Tropical Update 9/11/2017 4 PM CDT

Finally Over

I have been focusing on Irma’s insurance impacts since August 28th and what a ride it has been as we finally start to close the book on this historic event. Thankfully, its U.S. story will not be as historic as some of the early forecasts were suggesting last week. As I talked about just yesterday, Irma made a last minute eastward shift in track which will ultimately reduce insured losses from what was previously expected. Below are some of the surprises that have occurred over the last 24 hours that likely changed the overall outcome of insured losses.

Surprise 1 – Shift in Track East

Irma’s shift in track east is likely going to result in a much lower loss for the insurance industry. If Irma would have stayed just off shore, this would have put the highest winds right along some of the more urban centers along the western coast of Florida. If you look at the BMS iVision 3-second wind swath below, you will see that although some of the strongest winds are right along the coast, the core of Irma’s wind went right up the spine of the Florida peninsula.

This is the BMS iVision 3-second wind speed product. Notice that in central Florida is where the highest wind speeds were observed over land. Just right of the track which is typical of a hurricane. High winds are also observed at landfall location in Florida Keys and Marco Island.

 

This is the BMS iVision 1 minute sustained wind speed product. Again showing the highest wind were observed just right of the storm track in south central Florida.

 

This is the BMS iVision wind duration. It shows many areas along the east coast had persistent winds over a long time which helped build up the water along the East Coast of Florida creating storm surge issues far from the center of the storm.

This is a fairly remote section of the state consisting of mostly isolated small towns and pasture land. If these high winds would have tracked 30 – 50 miles further west, a lot more damage would have occurred up the western coast of Florida. By the time Irma tracked into the more populated I-4 corridor, it had already weakened and its winds were not as strong as they were over the south central part of the state. The highest winds and degree of damage I have seen are from a swath from the southern Florida Keys up to Naples and Fort Myers, with Marco Island just south of Naples taking some of the highest damage outside of the Florida Keys.

Irma Highest Wind Gusts

Overall, minor damage has been reported in other parts of the state and, as mentioned yesterday, this damage will be localized, depending on individual risk construction types and the frictional effects around each risk. Overall, it would appear that the winds across much of Florida were a great test to Florida’s strict building codes, which are some of the highest in the nation.

Surprise 2 – Water could not be replaced fast enough

As I mentioned yesterday, water was being sucked out of the bays and inlets ahead of Irma’s northward track due to the offshore winds. In some places, the water dropped to record low levels – yes Record Low levels, not high levels. As an example, the water in Naples dropped to -5.68 feet which is the second lowest  water level on record, but within two hours, the water rose over 9 feet, to 4.5 feet above mean sea level the highest on record.

Example of the seesaw in water depths along the west coast of Florida

So, the overall concern of high storm surge did not occur in many locations on the west coast of Florida because so much water was sucked away from the coast and could not be replaced fast enough, as Irma’s winds weakened during the track northward. This is not to say that some areas did not suffer storm surge damage. Everglade City and even the Miami area saw record high water, especially in the financial district of Miami. However the storm surge and flooding could have been much worse in cities like Tampa or Sarasota which will decease the overall insured losses from Irma.

Surprise 3 – East Coast Storm Surge

To some it was a bit surprising to see the high levels of surge and water damage along the eastern coast of Florida where the constant onshore winds allowed for record water build-up in the Jacksonville area.  As shown in the BMS iVision wind duration product above.

The storm surge in Fernandina Beach Florida, north of Jacksonville was higher than Matthew last year and just as high as when Irma was a strong category 5 hitting Barbuda back on September 6th.

Flooding in Jacksonville which seems to have been worse then hurricane Matthew just last year. Several high water levels have been set.

Surprise 4 – Power Outages

7 million customers were without power at one point. This is far more than the roughly 3 million that was predicted leading up to Irma’s landfall. However, with the high number of tree fall reports and high winds across the area, the number of outages is understandable. This also mean there could be more tree fall on structure that caused damage as well increasing the insured loss.  Power-outages could also cause issues for business increase BI related losses.

Last night image over South Florida. (top image) Showing the large area of power outage vs a normal night (bottom)

Insured Loss

Overall, the historic insured losses that were predicted even 24 hours ago will turn out to be wrong and although large losses will occur across the industry, there is a good chance that the Caribbean losses will be higher than what will be experienced in the U.S..  There are also many other factor that will also come into play as insurance losses are accounted for.  Irma could heighten the AOB issue that is ongoing in Florida because there is already a shortage of claims adjusters due to Harvey just a few weeks ago.

BMS Tropical Update 9/10/2017 11 AM CDT

Historic Day in Hurricane History

Today will go down as a fairly historic day in hurricane history on many fronts. It is still too early to determine what the insured losses from Irma in the U.S. will be, but the indications from modeling companies suggest they could be historic. Irma made landfall in the U.S. between Big Coppitt Key and Big Bine Key at 9:10 a.m. EDT, and is now just hours away from another landfall along the western coast of Florida as a Category 4 hurricane with winds of 130 mph and a pressure of 929 mb. In fact, only six U.S. landfalling hurricanes have had a pressure of less than 928 mb, including some well-known names such as Camille, Andrew & Katrina most recently. To my knowledge, this is also the first time in recorded history that the lower 48 states have had two Category 4 hurricanes make landfall in the same year. Also, it is interesting that Irma is making landfall on the same day and in the same general area that Hurricane Donna did in 1960, which I used as an analog earlier in the week. Lastly, today is September 10, which is generally considered to be the climatological peak of the Atlantic hurricane season. I guess that could be viewed as good or bad.

Climatology of the Atlantic hurricane season

Irma’s Size and Winds

 

Irma is tracking east of the 5 am NHC forecast.

Irma is still a large hurricane with hurricane-force winds extending 80 miles from the center of the storm. With Florida being about 100 miles at its southern tip across Alligator Alley, most of the southern part of Florida, including Miami, will experience hurricane-force winds. As Irma tracks northward, the far eastern part of the state likely won’t experience hurricane-force winds. However, with tropical storm-force winds currently extending 220 miles from Irma’s center, the entire state of Florida will likely experience tropical storm-force winds as Irma tracks northward over the next 24 hours.

This is the current NHC estimation of the size of Irma’s wind field as it crosses the Florida Keys.

 

Wind gusts near the center of the storm are already around 100 mph, with some weather stations falling in the high winds, such as at the Key West airport

A few things to keep in mind, however, are that most of the weather models don’t pick up on the very intricacies of the friction/roughness that occur at the surface. These intricacies can have a profound effect on the wind speed observed at a particular location. Some types of surface friction, such as an urban environment, can speed up winds due to the Bernoulli effect down city streets.

Although Hurricane Matthew impacted the eastern part of the state just last year, the full state has not had a storm of this magnitude in a very long time. This is important because there are many trees and structures that, for the lack of a better term, have not been cleaned out. Storms are a way to clean out older weaker trees and structures, and this will likely compound the amount of damage that occurs across Florida. In fact, social media is already showing many images of tree fall from the weaker outer bands of Irma, and this will only get worse as the winds increase over the next 24 hours.

Given that Irma’s track is expected to go right up the west coast of Florida, the major cities along the Gulf coast are likely to experience the highest winds Irma has to offer since the right side of the storm moving northward is always the strongest. Matthew last year had a different effect, where the east coast of Florida saw winds from its weak side.

Radar image as Irma tracked over the Florida Keys.. Showing the eye is about 20 miles wide

Irma has currently wobbled east of the NHC official forecast track, which means that it will likely make landfall around Naples, Florida at approximately 12:00 p.m. locally. However, with an eye that is 20 miles wide, many cities could experience calm conditions as Irma’s eye passes very close to the coastline on its northward track. This means that the high winds will come from many different directions over the course of the day, causing the possibility of additional damage. It should be noted that in the past with some hurricanes that are close to land, friction along its path could cause the path to deviate right with jog to the left, as Irma did along Cuba’s northern shoreline. This is not well understood, but it is a possibility as Irma tracks northward.

This is the latest BMS iVision. It does a nice job showing the detail that frictional effect can have on surface winds. BMS clients are using this to understand which wind speeds may be experienced at given risks along Irma’s path.

 

Current estimate of power outage along Irma forecasted path

 

Hurricane Hermine just last year showed us that a great deal of tree fall and long lasting power outages can occur with even relatively weak Category 1 winds. The Big Bend region in the northern part of Florida has a high density of tree cover that will compound the power outages and wind damage related to tree fall.

Storm Surge Impacts

NHC Storm Surge Forecast. Water will go out before it comes in

Irma’s current track position to the west of Florida is not ideal for creating large amounts of storm surge along the Florida’s west coast. This is because much of the water is being pulled away from the coastline as Irma tracks north. The back side of Irma will likely bring the largest storm surge as the winds switch to onshore flow, allowing water to build up along the western coast of Florida.

 

The highest storm surge forecast is currently found along Caple Sable island to Captiva, which is more southern facing, allowing for the water to build up along the coastline as Irma pushes northward. Surge values here could be over 15 feet above ground level. Storm surge into Tampa Bay is not the worst-case scenario for a Category 4 storm tracking towards Florida. Surge values here are expected to be 3 to 6 feet above ground level, causing some flooding in urban areas that have already been evacuated.

Rainfall

Noaa Rainfall Forecast

As expected, street and coastal flooding is already occurring in Miami. This should not be a surprise, as the Miami area floods even in high king tide situations. However, Irma’s rainfall and east side surge are compounding the problem as up to 15 inches of rain is still forecasted for much of the state.

Longer Term Forecast
Irma will track up the western coast of Florida over the next 24 hours, after which it will then move up into Georgia and Alabama early next week. During the middle of next week, the remnants of Irma could stall out over the Ohio river valley and create flooding issues.
Jose will loop up into the Bermuda Triangle, but it is still too early to determine whether it will impact the southeastern coast of the U.S. The probabilities of this occurring are low based on the current ECMWF ensembles.

ECMWF Ensemble forecast for Irma and Jose. 50% chance Jose impacts East Coast next weekend.

BMS Tropical Update 9/9/2017 12 PM CDT

Waiting for the Turn North

Did you know that the Associated Press has reported that 5.6 million people have been asked to evacuate Florida ahead of Hurricane Irma? To my knowledge, this is now the largest evacuation in U.S. history. The previous record was 3.7 million people who evacuated ahead of Hurricane Rita in 2005.

Irma made landfall in Cuba last night as a Category 5 hurricane, making it the first Category 5 hurricane to make landfall in Cuba since 1924. Irma has since weakened back down to a Category 4 hurricane due to half of the storm being over land, starving it from the warm waters of the Florida Strait. Irma should finally head more northwest today and turn towards Florida, which undoubtedly has been delayed. In fact, Irma is now at a longitude of 79.6W, very close to the longitude of Miami, so unless Irma takes one of the sharpest turns in hurricane history, a direct hit to Miami can almost certainly be ruled out. This has caused a drastic change in loss estimates from some of the scenarios over the last several days. However, with a shift in track to the west, this will now put the highest winds over Florida’s west coast and some of those major population centers.

The expected turn to the north should still occur, but as I talked about earlier in the week, the trend is your friend and the trend has been for the track to move west. This is actually bad for a couple of reasons. As mentioned, this would put the highest winds right along the west coast as Irma tracks north. It also puts Irma in the warm waters of the eastern Gulf of Mexico for a longer period of time, allowing it to gather strength and potentially be upgraded back to a Category 5 over the next 48 hours.

To give an idea of Irma’s size, I drew a circle around Irma to represent the size of the storm. I copied the same circle and moved it over Florida. Irma is a very large hurricane, so it is still possible that most of the state could see hurricane force winds as it tracks northward. However, given the westward shift in track, the strongest winds should now be well way from the populated tri-county Miami area of south Florida and the other east coast cities

s.

Steering flow still suggests a turn to the north, with the greatest weakness right up the west coast of the Gulf of Mexico.

 

Last night’s ensemble runs showing the greatest likelihood of Irma’s center passing over major west coast cities of Florida. These ensembles also show that the probability of a Miami landfall is still just as likely as Irma completely missing the Florida Peninsula and making a landfall in the eastern panhandle.

 

Storm Surge

This shift westward also significantly increases the storm surge risk along Florida’s west coast, which in general, has a much higher storm surge risk anyway due to the shallower bathymetry along Florida’s west coast.

 

Detailed Wind Swath and Expected Damage

The latest BMS iVision wind swath showing the true extent of damaging wind. BMS clients can use this wind swath to help understand the wind impacts at the individual risk level.

 

Source: http://ioe-guikema.engin.umich.edu/Hurricane_Irma.html This is the current estimated power outage outlook.

Expected Rainfall

There is now a chance that Irma could stall out across the southeastern U.S. later next week. However, in the near term, 15 inches of rain is still expected to fall over much of the sunshine state as Irma tracks northward.

 

This Morning’s – 9 AM EDT  BMS Tropical Update Webinar on Irma

This morning BMS hosted another webinar. If you missed this, I provided an update of the items being discussed in this blog in more detail, and our President Steve Korducki and Executive Vice President Julie Serakos covered the CEO check list of things companies should be doing at this stage and the current state of the market with summary of insured losses.

 

 

BMS Tropical Update 9/8/2017 11 AM CDT

Margin of error very slim now

As tough as this is for me to say, we are now in a window of model error (48 hours at about 50 miles) that suggests we are at the point where south Florida will likely see a catastrophic hurricane landfall. Based on some scenarios, this could be a historic and even game changing event for the Florida insurance industry. However, without yet knowing where Irma’s turn to the north will be, there is still some uncertainty around the exact impacts from the storm. Given how the models are now consistently suggesting a landfall location between Key West and Miami, several catastrophic scenarios are likely depending on the track. The consensus at this time seems to be that the landfall location could in the middle of the Florida Keys by early Sunday morning.

If there is any good news, it’s that as of this morning Irma is now a high-end Category 4 hurricane, likely due to an eye wall replacement cycle overnight. However, I feel this small downward tick in intensity will be short lived because some of the warmest sea surface temperatures in the world are in the southern Bahamas, and Irma is expected to track over this area. In general, I feel that Irma will be a strengthening storm as it heads toward the coastline, rather than weakening like Rita and Katrina did. Also, the overall environment continues to have light wind shear, so at this time it is expected that Irma will be a high-end Category 4 or low-end Category 5 hurricane with winds of around 155 mph as it nears the southern Florida coastline. This is likely near the building code requirements for most residential structures in south Florida. Of course, every building’s construction and the surrounding frictional effects will ultimately determine the damage at any given property.

Florida has some of the best building codes in the U.S. These codes were largely developed from past major hurricanes and will be tested with Irma. Source; IBHS

 

Summary of Impacts

  • Wind impacts will depend on slight east or west movements in track over the next 48 hours, with local building construction type and surrounding frictional effects ultimately determining damage. At this point, it is expected that the Florida peninsula will see damaging winds.
  • Storm surge is also dependent on track. The current storm surge forecast suggests that the Florida Keys and southwest coast of Florida could see the highest storm surge values of around 9 feet.
  • With Irma being a progressive storm, rainfall is expected to be around 15 inches

Wind Impacts
As suggested a few days ago, Irma will continue to grow in size. Irma is a much larger storm than many past hurricanes that have impacted Florida. In fact, this is a graphic put together by CIMMS/NASA that shows the comparison in size between Category 5 Andrew 1992 and the much larger Category 5 Irma as of yesterday.

Hurricane-force winds are currently extending outward up to 70 miles from the center, with tropical storm-force winds extending outward up to 185 miles. This means virtually the entire Florida peninsula will likely experience damaging winds regardless of track. The exact track, however, will determine where the core of the highest winds in the eye wall will be, about 30 – 40 miles from the center of the storm. Therefore, Irma’s exact track is still critical to understanding the total insured loss.

If we continue to follow the best performing ECMWF model, it puts a landfall location in the lower Florida Keys. This suggests that the winds will be just away from the urban core of the tri-county Miami area, lowering the expected insured loss, but any shift back east would increase this expected loss.

This is last night’s ECMWF model wind swath from Weatherbell. It only shows one scenario of expected winds across south Florida.

 

This is the BMS iVision Verisk Climate 3-sec wind swath. It is just one possible scenario at this time, but take note of the detailed frictional effect within the model.

 

Current estimate of power outages. Updates are shown here. http://ioe-guikema.engin.umich.edu/Hurricane_Irma.html

Storm Surge
Like the wind impacts, storm surge impacts are also highly dependent on track. Based on the NHC’s very detailed storm surge forecast, the Florida Keys and parts of southwest Florida will likely see the largest storm surge heights. The current surge value predictions in the Miami area are not likely to throw watercraft off their moorings, which would be critical to insured loss estimates given the high concentration of watercraft along the southeastern coast of Florida. However, with a change in track and if the storm moves up the coast, I expect these east coast storm surge values to increase putting watercraft at risk.  Also, storm surge needs to be watched carefully in the Jacksonville area as Irma tracks northward.

NHC Storm Surge Inundation from the NHC Advisory 37. Latest forecasts of surge found here. http://www.nhc.noaa.gov/graphics_at1.shtml?cone#contents

Rainfall
Since Irma will likely be progressing up the Florida coastline and not stalling out, the rainfall amounts should be more typical of a landfalling hurricane. Quantitative precipitation forecasts are currently suggesting upwards of 15 inches of rain.

Latest NWS rainfall forecast.

We have seen in the past that it does not take much rain in the Miami area to cause flooding, due to poor drainage and the built-up urban environment. Other areas to watch are the local channels and possibly the Lake Okeechobee level, which is currently at a low level. However, dikes that hold water in the lake are a known hazard and have grabbed national attention as critical infrastructure that needs to be shored up.

Current water level of Lake Okeechobee. Real-time information can be found here. http://www.weather.gov/mfl/lakeokeechobee

 

Longer Range Forecast  Irma
Just like the impacts to south Florida are dependent on the track shifts of west or east along the Florida Peninsula, the impacts to points north could vary as well. Currently, it appears that a west track is favored up the western side of Florida, which would keep the center of Irma over the Florida peninsula for much of the track and starve it of its energy as it moves northward. The negative aspect of a Florida track is that the entire east coast of Florida would likely see stronger winds, with a decreasing wind field as Irma tracks into Georgia and tropical storm-force winds across South Carolina early next week.

Insured loss
As mentioned in the last few blog posts, small shifts in Irma’s track will ultimately result in major differences in the outcome of insured losses. This is still the case today. Regardless, it is safe to say that Irma will likely be one of the costliest storms to impact the insurance industry. Irma’s track is very similar to some of the realistic disaster scenarios set up by rating agencies. These scenarios often suggest over hundreds of billions of dollars in insured loss. It is likely that the insured losses from this storm will at least be in the tens of billions of dollars, on top of over tens of billions of dollars in losses already from Irma’s strike in the Caribbean.

We will be able to have a better grasp on the exact magnitude of this event by tomorrow, as we will have a better understanding of the turn northward that will determine not only the south Florida impacts, but also the losses that may occur in other east coast states.

Replay of Special BMS Irma Webinar

Due to the special forecast situation and potential impact on the insurance industry, BMS Catastrophe Analytics held a Webinar on September 7th which provided the latest on Irma, its forecasted track and impacts for the insurance industry.

Quick note on Jose
As we know, catastrophe models are built on the concept of clustering. Hurricane Jose was upgraded yesterday afternoon to a major hurricane, heading for the northern Lesser Antilles and hitting the same areas that Irma hit with a peak intensity of 185 mph on Wednesday of this week. Please keep in mind that because of the widespread devastation seen from Irma, the vast majority of structures in these areas are already unsafe. In the long-range, Jose is expected to stall north of the North Caribbean during the middle of next week, with some models then tracking Jose west towards the Bahamas or eastern seaboard of the U.S. I will be watching this closely next week.

 

BMS Tropical Update 9/7/2017 12 PM CDT

The Critical Turn North

We are now in the critical 72-hour window before Irma’s expected interaction with south Florida.  The model runs overnight have been fairly consistent, but for a 72-hour forecast, there still seems to be a considerable amount of spread in the timing of the northward turn.  I have been blogging about what is causing this northward turn since last Friday, which is a trough of low pressure now positioned over the eastern half of the U.S.  I have also been mentioning that Irma would be breaking all sorts of records, which is certainly the case, as only three other Atlantic hurricanes have logged more time as a Category 5 hurricane than Irma.

What we know about Irma over the next few days

  • Irma will be a major Category 4 hurricane, and perhaps even a Category 5, as it approaches south Florida.
  • The likelihood of a landfall in south Florida is currently 85%.
  • The severity of impacts to Georgia and the Carolinas will ultimately be determined based on whether Irma makes landfall along south Florida or if Irma tracks up Florida’s east coast.
  • There is still a 55% chance that Irma will make landfall along the Florida Keys or points along the southwest coast of Florida.
  • Several models also turn Irma northward before a south Florida landfall which would result in less damage to Florida.
  • Based on my analysis of catastrophic model stochastic events, any Category 4 hurricane making landfall in south Florida will likely create at least a $10 billion insured loss event.

Uncertainty in Irma’s forecast improving

Although there is still a high amount of uncertainty in the short range forecasts, the evening forecast models are converging on the idea that Irma will be extremely close to south Florida by late Saturday night with a possible landfall early Sunday morning.  I have seen only a handful of models that do not bring hurricane-force winds to south Florida.  Most forecast models at this time suggest that winds in excess of 115 mph are possible across the major metropolitan corridor of south Florida.  I expect Irma to grow in size as it approaches south Florida, with hurricane-force winds easily extending 50 miles from the center of the storm.  However, if Irma tracks up the east coast of Florida, the strongest winds would stay on the right side of the storm, similar to what occurred with Matthew.  Irma looks like it could be larger in size than Matthew at this point in time though, so hurricane-force winds would likely have a greater reach inland than Matthew even if Irma tracks up Florida’s eastern coastline.


Depending on whether Irma makes landfall, the impacts beyond Florida could vary.  If Irma tracks up the middle of Florida, it would likely be in a much weakened state as it tracks northward.  If it stays just off the shores of eastern Florida, the hurricane would be in a much stronger state as it tracks up the coast toward Georgia and the Carolinas due to continuously being able to feed off the warm gulf stream waters, and it would likely be a major hurricane at any landfall points north.  Currently, for this model scenario, the border between South Carolina and North Carolina has the highest likelihood of landfall at 60%.

Specific Impacts

Wind Damage

With Irma’s forecast cone of uncertainty shrinking, the BMS iVision Verisk Climate wind swath product is providing its first views of what the expected wind damage across south Florida might look like as Irma makes its turn north.  It should be noted, however, that this is just one scenario of many that is still possible.

Storm surge

At this time it is too early to determine storm surge.  I expect the NHC to run scenarios based on the NHC official forecast beginning Friday.  They have already issued storm surge watches for much of south Florida.  Currently, Irma  is not a worst case scenario for storm surge.   At this point areas along the coastline could expect 5 – 10 feet of storm surge, which is highly dependent on storm movement and location.

Rainfall

At this point it looks like Irma should be relatively progressive, so unlike Harvey, it should not stall out over the Southeast.  However, large amounts of rain in excess of 15” could still fall over Florida as Irma tracks northward over the weekend and into early next week.  These rainfall forecasts will be revised over the next few days.

Irma’s Insured loss

Irma will likely already go down as one of the newest realistic disaster scenarios for the damage it has caused on the Caribbean islands, so I have little doubt the industry will be talking about its impacts to the area for decades to come.  Irma passed 50 miles north of San Juan, Puerto Rico, last night.  At that time, the strongest hurricane-force winds were on the north side of the storm and extended out from the center of the storm at an estimated 50 miles.  This is important because it appears that the northern coastline of Puerto Rico was spared widespread damage as the strongest winds stayed just offshore, although some local damage is being reported across social media.  This serves as a great example of why the storm track in relation to the radius of hurricane-force winds is critical in understanding the impacts we might see as Irma tracks up the East Coast of the U.S.  The catastrophe modeling companies are releasing event sets to help determine these impacts, but it is premature at this time to share the details of these losses aside from saying the losses will reach into the billions.

Over the last several days I have tried to finding analog events to match Irma’s intensity and there are very few.  Although there is less uncertainty in the forecast track today, there are too many different solutions, and how those solutions unfold could have a large impact on the heavily insured south Florida coastline.  Given these sensitivities, a difference of even 20 miles can influence loss amounts by the billions.

The catastrophe modeling companies should start issuing their pre-landfall preliminary set of tracks tomorrow which will give some early estimates, but these estimates will also change.  I think even tomorrow there will still be some uncertainty on the track Irma will take northward, either over Florida or off the coast.  As I mentioned, in a search for Category 4 events that make landfall in south Florida, it is hard to find an event with under $10 billion in insured loss.

BMS Tropical Update – Hurricane IRMA GoToWebinar

Due to popular demand for today’s webinar on Hurricane IRMA (4p ET/3p CT), we have changed the weblink for the webinar.

Please use the link below to register for the Webinar.

https://attendee.gotowebinar.com/register/7514724755448183553

Andy Siffert, VP/Meteorologist will be providing an update on Irma’s forecasted track and intensity.

Additionally, Julie Serakos, EVP and head of Cat Analytics will provide a modeling update and Kris Westall, COO and Urban Friesz, VP will provide an update on claims and accounting services.

Please join us for this important update.

BMS Tropical Update 9/6/2017 1 PM CDT

One For The Record Books

It appears that the global models have a common case of the flip-flops over the last 48 hours, which is typical with a complex forecast situation. We are also seeing some of the history books on hurricane intensity being rewritten. Based on information received from Phil Klotzbach at Colorado State University, Irma has now had a maximum wind of 180 mph+ for the past 24 hours, which is an Atlantic Basin record in the satellite era. This is just one of the many records Irma is breaking, and unfortunately it’s not done yet as it is still a Category 5 hurricane.

Caribbean Islands take a direct hit

Irma crossed several Caribbean islands overnight and is now moving in a slight west-northwest direction at 16 mph, placing it very near the U.S and British Virgin Islands. The damage I have been seeing across social media on many of these islands is heavy. This is to be expected from a Category 5 hurricane, as even some of the strongest buildings can sustain damage.

Below is a once in a lifetime sunrise as the northern Caribbean islands of Angulla, Saint Martin, Sint Maarten and St. Barts saw daylight break in the eye of the most powerful hurricane to impact these islands in recorded history.

 

Model Flip Flop and Irma’s Future Track
As we continue to watch Hurricane Irma strengthen and shatter the record books on intensity, the question of where Irma will go this weekend is still hanging in the air.  It’s all about the turn north, but when and where will that occur?
As I have been saying since Friday, a potential turn north all has to do with a weakness in the Bermuda high that will develop as a result of the passing of an upper level trough of low pressure on the East Coast. This turn north is very critical in determining Irma’s future track and any resulting impact to the U.S. insurance industry. This past weekend, we saw a lot of model guidance suggesting the possibility of Irma tracking up Florida’s east coast. On Monday and earlier Tuesday, the general model guidance was suggesting that Irma might track closer to the Florida Keys. As of last night and this morning, the model guidance is back to suggesting that Irma could track up Florida’s east coast. This is a classic case of model flip-flop in a very complex weather pattern, and the west and east coasts of Florida are still very much on the table as potential tracks for Irma. However, as I talked about yesterday, if you forecast with the trend, the trend is currently moving towards a track up the east coast of Florida.

Current Water Vapor Image detailing the global weather systems at play causing the model flip flop

The image above is the latest water vapor satellite image of North America. In this image, note the area labeled key polar shortwave. This is the shortwave that needs to be watched very carefully. This disturbance is forecasted to dive rapidly into the Mississippi River Valley within the next three days. The timing of this shortwave may cause it to interact with Irma as the storm moves into the Bahamas.
The concern here is that if this shortwave is stronger than some of the models suggest, than the upper level low will be able to form more quickly. If the upper level low forms faster in the Tennessee River Valley than expected, Irma will be forced to turn northward sooner over the Bahamas, and thus would become a threat for the Carolinas and possibly even Virginia. The possibility of Irma escaping out into the Atlantic Ocean with no landfall is still quite unlikely due to the position of the Bermuda high.
The location of this key polar shortwave is what I think is causing some of the model flip flop because that polar shortwave is in an area of poor sampling.  Therefore the global model guidance used to forecast Irma’s track has a high degree of error, and also why there is so much volatility in the models from run to run. The shortwave is also why the threat of Irma tracking east of Florida to locations further north to North Carolina remains on the table today. However, as I highlighted in yesterday’s post, a track into the Florida Keys and up the west coast of Florida is still a possibility – it’s just not a favorite model solution today.  As shown below, even the NHC official forecast for days four and five are seeing large adjustments, and these forecasts have errors of 175 and 225 statute miles, respectively.

With so many models, it is important to keep track of which model is performing the best. Currently, the ECMWF has the lowest track error at days 4 and 5.

 

This is the current ECMWF and its ensemble of probability. Currently, Florida is at the highest risk of seeing Irma landfall. However, many model members of the ensemble also track Irma into the Florida Keys and up the East Coast.

 


Irma’s future intensity
While the models have a case of the flip-flops in terms of the forecasted track, what is remarkable is that there is very little disagreement on Irma’s future intensity. Since last Friday when I first started writing about Irma, it was well forecasted to become a major Category 4 or 5 hurricane impacting the northern Leeward Islands. These forecasts have been remarkably consistent in an era when forecasting intensity is typically the biggest challenge.

At this time it looks like Irma will track far enough away from the mountainous Hispaniola, which would have a significant impact on the circulation of the storm. Because of this and the warm sea surface temperatures along Irma’s track, the models have been forecasting a major hurricane to impact the southern Bahamas and south Florida for several days now and they are not backing away from this prediction.  At this point it is a very safe bet, depending on track, that Irma will be a major hurricane (likely a Category 4 or stronger) near Florida by early Sunday morning. If Irma does not make landfall in Florida, the areas along the coasts of Georgia and the Carolinas should also be prepared for a major hurricane landfall.

 

Current water average water temperature along Irma’s forecasted path. 29.3C is 84.7F

 

New Analog Events and Insured Loss

I have been trying to find analog events for Irma, but there are very few events of this intensity that have tracked up the east coast of Florida. The events I provided yesterday would still fit in the model solutions today. However, David 1979 could be used as another possible Florida analog impact, but it was a weaker Category 2 hurricane as it tracked up Florida’s east coast. Due to the current intensity, any historical loss comparison can’t really be used at this time because Irma is expected to be a much stronger storm than anything I could find that has tracked up the east coast of Florida.

With the forecast uncertainty around the potential turn north, it is too early to provide detail on what potential losses could occur. However, just taking a glance at some of the disaster scenarios from catastrophe models, any hit at Category 4 or greater to southern Florida would be at least a $15 billion loss. Some of these scenarios only go up depending on the landfall location, such as a $100 billion loss or even greater, from a direct Miami hit. The ranges of potential losses are great. Matthew, however, showed us that if a storm can track just offshore, it can spare large levels of loss.

Special BMS Webinar Tomorrow

BMS Tropical Update – Hurricane IRMA GoToWebinar

Due to popular demand for today’s webinar on Hurricane IRMA (4p ET/3p CT), we have changed the weblink for the webinar.

Please use the link below to register for the Webinar.

https://attendee.gotowebinar.com/register/7514724755448183553

Andy Siffert, VP/Meteorologist will be providing an update on Irma’s forecasted track and intensity.

Additionally, Julie Serakos, EVP and head of Cat Analytics will provide a modeling update and Kris Westall, COO and Urban Friesz, VP will provide an update on claims and accounting services.

Please join us for this important update.

BMS Tropical Update 9/5/2017 12 PM

Irma Heading Into The History Books

I mentioned in Friday’s BMS Tropical Update that Irma would become a major hurricane, possibly a Category 5, near the Leeward Islands. As of this morning, Irma can be found 180 miles east of Antigua and moving at 14 mph, officially a Category 5 hurricane. In terms of wind, Irma is the strongest hurricane in the Atlantic Basin since Felix 2007, and in terms of pressure, the strongest since Igor 2010. Regardless of history and what records might be broken by Irma over the next few days, the fact is that it’s a large and dangerous hurricane not seen in the Atlantic Basin in a long time, and it likely won’t weaken below a major hurricane this week as it tracks closer to the U.S. coastline.

In the short term, Irma will remain a major hurricane as it impacts the northern Leeward Islands later tonight and into tomorrow. These small islands will likely suffer a significant amount of damage as it has been a very long time since a hurricane of this magnitude has impacted these islands (e.g., David 1979 and Sept 1928).

Only 2 Category 5 in NOAA’s best track database w/in 200 nm of the Northern Leeward Islands: David (’79) and Sep. 1928. Both were Category 5 after center passed Leewards Islands.

Irma will track into the southern Bahamas toward the end of this week. There is a chance Irma could weaken slightly due to land interaction with the northern Caribbean islands, but the water in Irma’s path has plenty of energy, which will limit any weakening in the coming days.

The tropical cyclone heat potential (TCHP), is defined as a measure of the integrated vertical temperature from the sea surface to the depth of the 26°C (78.8°F) isotherm. The warmer the more fuel for hurricanes.

Meteorological Rule of Thumb

In my last update, I mentioned that Irma’s ultimate track could be influenced by a trough of low pressure that is now moving into the Upper Midwest and will be hanging around the East Coast for the next several days. Below is a great illustration I found by Philippe Papin, a PhD student studying atmospheric sciences at the University of Albany.


As Philippe mentions, Irma will be moving along the southern edge of the Bermuda high pressure over the next several days. At the same time, a deep trough of low pressure will be moving to the East Coast. This steering flow around the high and the deep trough will begin to turn Irma to the northwest later this week. However, the combination of the trough of low pressure, which gets elongated along the East Coast later this week, and the strength of the Bermuda high likely won’t allow for Irma to turn north before it gets to the Florida coastline. However, what will likely happen is that it will allow for an abrupt northward turn in Irma’s track later this weekend as the storm is near south Florida, when Irma is on the southwestern periphery of the Bermuda high. This abrupt change in track northward means Irma could significantly slow its forward motion as it turns northward late this weekend into early next week. This increases the chance of major inland flooding due to its slower forward motion.

All of this meteorological assumption is based on an understanding of large scale atmospheric motion 120 hours from now, which is five days. Although five day forecasts are improving, small details in the large scale motion can have a big impact on where Irma ultimately makes landfall. In fact, the NHC track errors on a four and five day forecast are 175 and 225 statute miles, respectively.

According to the University of Albany, which keeps track of model forecast errors, the NHC’s five day forecast error is currently running about 200 miles.

Current mean absolute error for Irma forecast tracks from various weather models.

Keep your eye on the ECMWF model, which currently has a very low track error, but overall it’s bound to errors as well. Just look at how the 10-day ECMWF ensemble forecast (an ensemble is a forecast of 52 similar forecasts with different settings) has already evolved for Irma since Friday.

This is the ECMWF Ensemble Forecast from last Friday of all the various track scenarios for Irma.

Irma has been consistently defying the modeling of a northward turn up the East Coast, which was the most common model ensemble solution last Friday. Today fewer ensemble forecasts track Irma in between Bermuda and the East Coast.

This is last nights ECMWF Ensemble forecast which show a much more westward track.

In fact, as I talked about the recurving typhoon rule in my Friday post, I was thinking of another rule that is taught in meteorology school – don’t forecast against the trend. In this case, the trend has been for Irma to track further westward, meaning the chances of Irma ending up in the eastern Gulf of Mexico early next week are much higher today than even just a few days ago. Regardless, Irma will likely have an impact on south Florida along its forecasted path. Based on the latest forecast, there is an 80% chance that Florida will see a major landfalling hurricane.

Initial Insurance Analog Events For Irma

The probability is high because Irma will be a very large hurricane this weekend, with a large eye and hurricane force winds that could extend out from the center for up to 50 miles. With the southern part of Florida only being separated by just over 100 miles from east to west, it seems very likely that some part of southern Florida will be exposed to hurricane force winds.
At this point, the insurance industry should be preparing for another U.S. landfalling hurricane. To help understand the potential impacts at this early stage, a few analogs come to mind. Donna 1960 could be a good analog to the forecasted track of Irma over the next few days. If Donna occurred today, the Florida wind and surge insured losses could amount to $13.6 billion according to one catastrophe modeling firm. Potentially a more extreme analog might be the 1935 Labor Day Hurricane, which today would cause an estimated insured loss from wind and surge for Florida at around $40.7 billion.

There is still a great deal of uncertainty in the forecast for later this weekend, and there are many different scenarios that could play out. One thing for certain is that there has been a large population growth in Florida with a 27% increase in the number of homes since 2000, according to the U.S Census. The exposure is significant, and if Irma arrives with major hurricane force winds, the current building codes over much of the state will likely be challenged.

BMS Tropical Update 9/1/2017 12 PM

As mentioned in the last BMS Tropical Update, it’s a bit early to determine where hurricane Irma will be heading 10 to 15 days from now, which is when it could be eyeing a potential U.S. coastline impact. However, as much of the U.S. insurance industry heads into a long weekend, here is what my gut thinks will happen with Irma over the next 10 days.

When forecasting in the long range, it is important to look at what is occurring worldwide. There is a very good chance that Irma’s future track will be influenced by what is going on in the West Pacific. Currently there is a typhoon named Sanvu southeast of Japan. This typhoon is expected to recurve into the westerlies over the next few days.

Current location and track of Typhoon Sanvu in the West Pacific Ocean

There is a general rule of thumb in meteorology that when this occurs, it could cause a trough of low pressure to move towards the U.S. East Coast between 6 to 10 days later. This means that if the typhoon recurves as forecasted over the next few days, a trough of low pressure could potentially be on the East Coast sometime between September 7th and 11th. In fact, some global models are picking up on this trough of low pressure for next week. Some even produce the first frost of the season for parts of the Upper Midwest, so it will have some punch.
Around September 7th and 8th, Irma will be a major hurricane and will likely be a Category 4 or perhaps even a Category 5 over or near the Leeward Islands. This will result in three potential scenarios for later next week, based on the forecasted trough of low pressure and Irma’s latitude at that time:

  1. Irma could be at a high enough latitude that it gets pulled north by this trough of low pressure, similar to Gret’s path the second week of August, and recurve in between the U.S. and Bermuda.
  2. Irma could be at a low enough latitude that it misses getting pulled into the trough of low pressure and tracks south of Puerto Rico, perhaps into the Gulf of Mexico.
  3. If Irma is near the Northern Leeward Islands, it could get pulled up by the trough of low pressure, but miss the full connection, and head towards Florida and the East Coast with a close landfall threat later the following week.

Right now this might be the best graphic I have found on the future of Irma. Its based on the ECMWF Model, but it provides a good long range outlook at this time of the three opitons above. Source The Weather Channel

 

Based on the current forecast of Irma being a major hurricane near the Leeward Island next week here is a history of all the major hurricane over this forecasted area and where they tracked. It follows The Weather Channel guidance nicely, but keep in mind this is history and not a forecast.

At the start of the season, I thought the East Coast was going to be the biggest threat of landfalling storms in the U.S., and I don’t see a reason why that should change. Based on the forecast and history, there is currently a 60% chance of Irma impacting the U.S as at least a tropical storm, and  a 30% chance of seeing a major hurricane impact at this time.

As a reminder, I still feel that the MJO will make it more difficult for new storm formation between September 10th and 25th, so the peak of the season could be quiet for new development.