BMS Tropical Update 9/20/2017 4 PM CDT

2017 Atlantic Hurricane Season Records Continue To Fall

The 2017 Atlantic hurricane season, which has already been memorable, continues to create long-lasting memories which will likely be talked about for decades. The newest talking point is Maria’s landfall at 6:35 this morning near Yabucoa, Puerto Rico. Maria arrived as a top end major Category 4 hurricane with maximum sustained winds of 155 mph and a pressure of 917 mb. Maria will likely be the strongest storm in terms of pressure to make landfall in Puerto Rico since 1928 – in terms of wind, it’s the second strongest. It is also the third most intense (by pressure) U.S. hurricane on record to make landfall behind Hurricane Camille, and the  Labor Day 1935 hurricane.

The statistics and images coming out of Puerto Rico indicate that Maria will likely be one of the largest natural catastrophes the island has ever experienced in terms of insured loss. But, I won’t dive into the devastation that has already occurred on the island, which is being covered extensively, but rather focus on the uncertainty of Maria’s long-term impact on the U.S. mainland.

Maria’s U.S. Mainland Threat

The geography of Puerto Rico has had a tremendous impact on Maria’s current intensity. The infrared satellite imagery above shows that the storm’s interaction with the high mountains has resulted in weakening, with a clear eye no longer visible. Unfortunately, this makes the storm no less dangerous, as winds well over 100 mph continue to beat the island. Torrential rainfall will remain as well, with totals nearing two feet in the higher terrain. Flash flooding and mudslides will be major issues for the next few days as Maria begins to move away from the island.

As Maria moves today toward the northwest, this weakening could influence the future track of the storm over the next week which, at this point, is still uncertain. A wobble south toward Hispaniola would result in a weaker system that may allow for a track farther west in the long term. The current forecast track takes the storm just north of Hispaniola, where the effect of land interaction would be minimal, thus keeping Maria on a more northwest track away from the East Coast of the U.S. next week.

The other complicating factor is the continued influence of Tropical Storm Jose, as discussed in my Monday update. Jose has already been a named storm for 15 days, which ties it for the 10th longest named storm since the beginning of the satellite era. Jose is still a large storm and, if it were not for Maria, would be a front-page news story. However, as I previously suggested, its insured impact has been minimal and similar to that of a nor’easter.

Currently Jose is doing another small loop off the New England coastline and is expected to continue to weaken over colder water as it moves back to the west later this week.

Reposting this image as the general ideas still holds from Monday thinking on overall pattern driving the northward turn of Maria.

Maria is expected to follow this weakness in the upper level ridge that Jose has created. However, the exact movement is a bit uncertain based on Maria’s trajectory away from Hispaniola and how far west Jose actually tracks. The general model guidance currently keeps Maria away from the East Coast. I do, however, expect the western edge of the National Hurricane Center’s cone of uncertainty to be very close to the coastline of North Carolina and Massachusetts as the five-day forecast cone expands northward over the next few days.

Right now, the forecast models have a bias that sometimes curve hurricanes northward  moving the hurricane to the northeast. If there is an error, it would result in a greater correction to the west with each model run.

Current long range track ensemble guidance from the American (GFS) and European (ECMWF) models. Most ensemble members keep Maria off the East Coast of the U.S. Some members however offer up landfall options all along the Northeast Coast of the U.S.

Currently, there is a 30% chance of U.S. landfall in New England per the American(GFS) ensemble model and a lower 10% chance from the ECMWF ensemble model. It should be noted, however, that cooler water temperatures and increasing wind shear will result in weakening of Maria as the storm moves northwest and then north this weekend. It would likely only be a Category 1 hurricane north of North Carolina.

Next Area Of Tropical Troubles

This is the next area to watch. This is the forecast valid for Oct 6th suggesting low pressure will be across the Western Caribbean

The next area to watch will be the western Caribbean, as the longer range models are suggesting tropical cyclogenesis in early October.

BMS Tropical Update 9/18/2017 12 PM CDT

Although there are no current threats to the U.S. mainland, I would like to provide a brief update on the thoughts that were discussed in Friday’s Tropical Update.

Below are a few key points about each tropical system:

Tropical Depression (TD) Lee:
TD Lee is currently 1060 miles west of the Cabo Verde Islands and is a weak tropical depression. It has weakened significantly since being named a tropical storm on Saturday morning and is now battling dry air and wind shear. Lee is expected to dissipate over the next 24 hours and will not likely be a threat to the insurance industry.

Hurricane Jose
Jose is currently 265 miles east-southeast of Cape Hatteras, NC and is moving north at 9 mph. It is currently a Category 1 hurricane.

Jose continues to show signs of weakening on satellite imagery as dry air is wrapped into the circulation. It will likely continue to weaken as it moves over increasingly cold water, as discussed on Friday. It should turn into a subtropical system later this week.

The outer bands of Jose will arrive on the coast between Boston and Cape Hatteras on Tuesday morning. These bands will feature breezy conditions and light/moderate rain. Overall, there should be minimal impact on Tuesday as rain bands continue to rotate onshore.

The one area of concern that’s been a given since the beginning loop early last week are the large waves that will continue to pound all ocean facing beaches in Delaware, New Jersey, Long Island, Rhode Island, and Massachusetts. Beach erosion will be an issue for the typically at-risk areas. Additionally, astronomically high tides will fuel coastal flooding concerns for low-lying areas as persistent onshore winds push a slight storm surge into eastern Massachusetts and the Long Island Sound. Waves and surge will gradually subside on Thursday as the storm weakens.

Beyond Thursday, Jose will become trapped between two upper level systems. As a result, it will linger off the New England coast as it weakens due to the cold waters in the region. In the long range, there is a chance that its remnant moisture could loop around back into coastal New England and play a role in Maria’s long-term forecast, as discussed in more detail below.
At this time, the threat of major insured loss from Jose is low.

Hurricane Maria

Hurricane Maria, which was Invest 96L when discussed on Friday, was my biggest concern due to its track toward the Windward Islands. It is now 60 miles east of Martinique as a Major Category 3 with sustained winds of 120 mph.  Rapid intensification is still expected today and it looks like Maria could have a small eye suggesting a tight central core with very strong winds.

These continued signs of intensification are likely due to  warm waters not affected by Irma up-welling.  Richard Dixon @catinsight has put together a nice little graphic showing that there is currently little overlap across the Caribbean islands between the hurricane-force winds from Hurricane Irma and the forecasted wind swath for Maria. The overlap could occur near Puerto Rico, which will likely be impacted by Maria as a major hurricane on Wednesday of this week.


In the long range forecast, Maria still has some uncertainty not only in intensity but also with its future track. These go hand and hand. There is a chance that Maria could be weakened by the high topography of Puerto Rico, depending on its track over the island. Parts of the various ensemble model guidance from last night showed Maria moving west and dissipating over the high mountains of Hispaniola and Southern Cuba. Some model guidance also points to a Florida landfall or potentially even a track into the Gulf of Mexico. Many more ensemble members point Maria up the eastern seaboard, with impacts spreading all the way to the mid-Atlantic. Finally, the storm could recurve out to sea before impacting land. So, which of these scenarios is most likely in the long range?

All the ensemble runs from last night showing all the possible tracks for Maria. Currently there is only a 5-10% of landfall given the ensembles Map provided by Allan Huffman and models.americanwx.com

To understand that question we need to look at the bigger atmospheric pattern. The upper level forecast map from the ECMWF for Thursday shows a complex and highly amplified pattern over North America.

ECMWF forecast for this Saturday with highlights of the different features that will determine Maria’s future track.

The jet stream will be in what’s called a meridional flow pattern with high amplitude waves. This pattern is being driven by the recurvature of Typhoon Talim, which was previously discussed, and tends to cause a trough of low pressure to form along the East Coast 6-10 days later. However, it would appear that the blocking high pressure over the Great Lakes will attempt to stay in place. Jose will stand in the way from the high building back to the East. Therefore, this will likely create a weakness in the ridge. How quickly Jose can either leave the scene or weaken will have a huge impact on how quickly the ridge can rebuild, and thus will play a role in Maria’s track over the long range.

It appears at this point that Jose will be around until this weekend, which should attract Maria up to the east of the Bahamas. Maria will likely follow the path of least resistance around the Bermuda high and the weakness Jose has produced within the high pressure along the western part of the Atlantic Ocean. This would keep Maria away from the U.S. coastline. Although it currently looks like Maria will stay away from East Coast of the U.S., there is still some uncertainty in the long range. The overall forecast pattern is complex with several moving puzzle pieces that will come together later this week.

The insured impact from Maria will be high in the short-term as it will be a major hurricane when it interacts with some of the Caribbean islands yet to see impacts this year. Puerto Rico will likely take a direct hit from Maria.  The last such major hurricane was Hurricane Hugo 1989.


The insured impact in the long-term is unknown at this time, given the uncertainty in the forecast.  Currently there is only a 5 – 10% chance Maria would make U.S. landfall given the current ensemble forecasts.

Other Tropical Troubles

There is nothing else to worry about at this time off the coast of Africa.  Lots of dust and dry air and little convection over Africa.

Current Dust Layer from http://tropic.ssec.wisc.edu/

The next tropical development could occur near the coast of central America later next week, but this is with low confidence and little model support in the long range. However, this is an area to watch as October approaches, when the Main Development Region (MDR) tends to shut down and new named storm development tends to form in the western Caribbean as climatology suggests below.

Source: http://www.nhc.noaa.gov/climo/

BMS Tropical Update 9/15/2017 12 PM CDT

More Tropical Troubles

First and foremost, I had previously mentioned several times I thought the Atlantic Basin would shut down for a few weeks due to the suppression phase of the Madden-Julian Oscillation (MJO). Unfortunately, the MJO is currently in a weakened state and the large-scale subsidence is not strong enough to overcome other climate forces that are allowing for new named storm formation in the Main Development Region (MDR). In this case, it could be tied to a convectively coupled Kelvin Wave which is likely enhancing the development of new named storms in the MDR.

Data suggesting a Convectively Coupled Kelvin Wave could be the climate forcer that is allowing for development in the MDR.

So, with the understanding that the insurance industry is still in the early stages of tallying the losses from Harvey and Irma, there might be a need to inquire about additional capacity for the remainder of the year. Therefore, I want to provide a bit more detail on what to expect in terms of tropical troubles for the remainder of the month.

Jose End Game

Hurricane Jose has been on the radar since it first tracked off of Africa on September 4th and passed just north of the Leeward Islands on September 9th. It then tracked into the Bermuda Triangle where it has done a large loop. Jose is in the process of finishing its dance in the Bermuda Triangle and will slowly track northwest over the next several days.

The risk of Jose’s impact on the U.S. had been relatively low (less than 20%) until the last 24 hours. With better long-range modelling, however, we can now get a clearer picture of what the end game might entail for Jose. In fact, currently the official National Hurricane Center (NHC) track puts a good chunk of the coastal Northeast just inside the “cone of uncertainty,” which means there is now a chance that Jose will directly impact areas from the NC Outer Banks to points north, including Cape Cod, later next week.

This is the American GFS Model Forecated Trend heights at the middle of the Atmosphere. Showing a trend of higher heights which means more blocking to the north of Jose’s track.

The key to the forecast is going to be just how strong and how far west the Atlantic ridge of high pressure is as Jose begins to turn north this weekend. Also, with the ridge of high pressure trending stronger north of New England next week, the general idea that Jose will escape out to sea is becoming more uncertain, given this large-scale atmospheric pattern. This could allow for Jose to track into New England versus turning east. So, once again, there is some long-range forecast drama to watch next week. My general feeling is the high pressure to the north looks to be stronger, which means the probability of landfall is now as high as 70% for parts of New England on Thursday of next week.

In terms of intensity, although the NHC is not forecasting Jose to become a major hurricane on its current path towards the East Coast of the U.S., I think there is a decent chance that Jose could become a solid Category 3 again before encountering cooler waters north of North Carolina.

As Jose tracks northward west it will first run into warmer than normal water before it tracks over cooler than normal waters.

These cooler waters will be a critical factor in how intense Jose becomes after Wednesday of next week.  Currently these sea surface temperatures of 23 C / 73 F are not very supportive of a hurricane.

Current surface water temperatures off the east coast of the U.S

This will likely result in a much weaker storm,  but it depends on how strong Jose can get earlier next week.  Right now a Category 1 hurricane impacting the East Coast next week can’t be ruled out, but it is unlikely.  There is a better likelihood of Jose becoming extra tropical at this point and could even slow and become a bigger rain maker late next week.

Next week I can provide more details about the possible impact once the track becomes more stable, but, at this time, big swells will be increasing along the East Coast which will cause beach erosion. As Jose tracks closer to the East Coast, the most likely scenario is that it will track just off shore, which would mean that the strongest winds on the right side of the storm would stay off shore, but coastal flooding could be an issue, as the winds possibly push water down Long Island Sound and against the New Jersey coastline later next week.

Main Development Troubles

Meanwhile, last night the NHC upgraded a tropical wave coming off of Africa to Tropical Depression (TD) 14. It will likely develop into Tropical Storm (TS) Lee later today and should eventually turn north to the open Atlantic. However, this should be watched more closely, as the general steering flow this year has indicated that these tropical systems are tracking closer to the U.S. because of the Bermuda High. To the west of TD 14 is an invest area labelled 96L which could become TD 15 or TS Maria at some point as it cruises west toward the Windward Islands later next week. Currently the NHC has a 50% chance of cyclone formation over the next two days, but a 90% chance of formation over the next 5 days.  It should be noted both Invest 96L and TD 14 will run into higher wind shear which could weaken the systems as they track westward this weekend. If the storms do last until early next week, expect Invest 96L to be close to the Windward Islands and TD 14 to be tracking northeast toward the Leeward Islands.  I am most concerned with Invest 96L at this time, because as it gets closer to the U.S Caribbean, we have seen this season that conditions are more conducive for East Coast impacts.

General ideas of track of current tropical systems into next week.

Regardless, this is simply a busy season, the likes of which we have not seen since 2012. It is important with all of the other news and distractions going on around the world and locally that we remain focused on hurricane preparedness and these future storm threats.

Hurricane Irma – BMS webinars discussing developments

Tropical Update Webinar one – 7 September 2017
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.

Tropical Update Webinar two – 9 September 2017
In this webinar BMS President Steve Korducki and Executive Vice President Julie Serakos cover 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 9/11/2017 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.