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BMS Tropical Update 9/29/2016 11 AM CDT

As of 11 am EDT the  NHC suggests Tropical Storm Matthew is close to a hurricane with a location 290 miles south of San Juan Puerto Rico.   With any of the next advisories the named storm could be upgraded to a hurricane.

Forecasted Intensity

As highlighted over the last two tropical updates Matthew will be moving over warm water and it will be this warmer than normal water that will provide the fuel for Matthew to strengthen into a major hurricane by Monday.   Over the next few days as Matthew moves westward wind shear will limit rapid strengthening of the system.

After Matthew starts its turn northward it should rapidly strengthen and will likely be a category 3 hurricane near the Eastern shores of Jamaica or Haiti.  In the longer range forecast for later next week one could expect some slight weakening of the system as it interacts with higher terrain from the mountains of Cuba and Haiti.

929matthewshear

 

Forecasted Track

929matthewnhctrack

nhcerror

Now is a good time to remember what the National Hurricane Center cone of uncertainty means.   A layer that is within BMS iVision it does not reflect real-time uncertainty within the forecast of Matthew. The width of this uncertainty is solely determined by historical errors of past hurricane tracks and not the current uncertainty with track spread within Matthew.

The NHC lists five important points to help users understand the cone.

  • The cone represents the probable track of the center of the tropical cyclone.
  • The size of the cone is drawn so that about two-thirds of the time, the center of the storm will remain in the cone.
  • The cone does not take the size of the storm into account.
  • A hurricane is not a point; impacts often occur well outside of the core.
  • The cone indicates the forecast up to five days out from the last recorded position of the storm.

Overall I like the ideas the NHC has forecasted for the next 5 days.  I think the NHC may slightly shift the track closer to Jamaica over the next few days, but in general the forecast model guidance suggests that Matthew should be either near Jamaica or Haiti by Monday and most of these forecasts have Matthew as a major hurricane at this time.   After this there still is a great amount of uncertainty in the long range forecast from days 5 – 10.

The key will be how Matthew interacts and turns with the upper level trough of low pressure.

929matthew_turn1 929matthew_turn2

There is some indication that Matthew could stall out near the Bahamas early next week, maybe similar to what happen to hurricane Joaquin last year.  However, below is a look at just how much uncertainty there is with the 10 day forecast from the ECMWF ensemble showing the low pressure centers from the latest model run.

929matthew_ecmwf_lowlocations

Right now the Gulf Coast states look to be in the clear, but Florida and points along the East Coast need to pay attention to this  complex forecast situation in the long term.

GFS Ensemble Long Range forecast tracks for Matthew

929matthewgfsoptions

ECMWF Ensemble Long Range Forecast Tracks for Matthew

929matthewecmwfoptions

Since 1900 the only major hurricane to make landfall after today north of Florida along the U.S. East Coast was Hazel in 1954 near the NC/SC Border and in some regards Matthew has some similarities in the long range forecast.

BMS Tropical Update 9/28/2016 12 PM CDT

As I wrote about this past weekend, Tropical Storm Matthew would likely form over the southern Caribbean islands and there was uncertainty in the long range forecast of where Matthew might end up in the long range.   Well, sure enough this morning Matthew formed just east of the Caribbean as a strong 60 mph tropical storm. Forecast models continue to suggest this storm will intensify over the next several days.  Unfortunately no one knows where Matthew will make landfall at this point and it is far too soon to provide specifics to what will occur later next week.

What we do know

In general we know Matthew will continue to move westward across the southern Caribbean Sea for the next several days.  As Matthew moves westward it will move over very warm water and as I pointed out on Sunday this water is much above normal temperature.

928matthewsst

928matthewheatcontent Above is the current Sea Surface Temperatures and Tropical Cyclone Heat Potential both of which can support a major hurricane.

We know if wind shear decreases it will allow for rapid strengthening of  Matthew over this very warm water so in general the likelihood of a major hurricane (Category 3 with winds 111 mph or greater) is likely to happen by this weekend.

928matthewintensity

Current Forecast intensity model guidance for Matthew. There is little doubt Matthew will be a hurricane soon and likely a major hurricane later this weekend

We know that the short term forecast of Matthew will allow for a storm’s track of a westward motion over the next four to five days. We also know for the last several days the forecast models have been consistent in suggesting the storm will turn north in the central Caribbean.  This means insurance companies from along the Gulf and East coasts should be aware that there is the potential for a hurricane landfall sometime in the middle of next week.

What we don’t know

What we don’t know is the overall end game for Matthew at this time which should unfold later next week.  This is because the timing of the northward turn is still unclear.  The American Global Forecast System (GFS) weather models suggest the storm will begin to turn on Saturday in the central Caribbean, hitting Haiti on Sunday and then miss Florida but then could impact parts of the East Coast late next week. The European (ECMWF) model is forecasting the sharp turn later on Monday next week therefore allowing for a farther westward track into the Caribbean. In that scenario, it would hit Cuba on Tuesday and have a good chance of impacting Florida or moving into the Gulf of Mexico.   These are the two best long range weather models available and they offer different outcomes on what could occur next week.  As I have pointed out before there is no certainty in a long range forecast, but general ideas can start to take shape so at this time don’t follow just one forecast, look at all the possible solutions.  However, if I were to place a bet on which model might be right next week I would choose the ECMWF model.

928matthewgfsoptions

This is the GFS Ensemble Model Solutions suggesting a earlier turn to the North.

928matthewecmwfoptions

This is the ECMWF ensemble model solutions suggesting a more westward track.

Historically, tropical storms in October tend to turn north sharply after they reach the Caribbean. Looking back at a few storms that made a sharp turn to the north, like this storm is expected to do, one of the most recent would be Wilma which was the last major hurricane to hit the U.S. 3993 days go. Wilma made a very sharp turn northward near Mexico’s Yucatan Peninsula before hitting Florida.  Another noteworthy storm was  Hurricane Hazel in 1954 which looks very similar to what the models are forecasting for this week’s storm. Hazel formed just before reaching the Caribbean, turned abruptly to the north and passed between Hispaniola and Cuba impacting the east coast of the U.S.

BMS Tropical Update 9/25/2016 11 AM CDT

At the start of the 2017 hurricane season you might remember the general prediction  was tropical systems will struggle over the main development region due to dry air and at times high wind shear.  However, as tropical systems take shape and move westward towards the Caribbean or U.S. coastline, the overall environment will become better for storms to strengthen.  So far this has been the case this season.

New Invest 97L

With little activity in the Atlantic Basin as Tropical Storm Karl swiftly moved across the North Atlantic the media is starting to hype the next tropical system.  This system has been tagged by the National Hurricane Center (NHC) as Invest 97L.

Currently Invest 97L is struggling with dry air and higher wind shear, but the system is starting out at a fairly low latitude, south of 10 degrees which generally means the system will track further west vs slowly curve to the north as it tracks westward across the Atlantic Ocean.  Steered by the subtropical ridge of high pressure known as the Bermuda-Azores high, Invest 97L will arrive in the Windward Islands on Wednesday bringing locally heavy rain and gusty winds. Such locations as St. Vincent and the Grenadines, Grenada, perhaps Trinidad and Tobago could be targeted islands.

You might have noticed that the (NHC) has given this system a high chance (80%) for formation into a tropical depression over the next 5 days. And many global models are suggesting a hurricane to develop after the system crosses the Windward Islands. The next named storm will be named Matthew.

invest97l

There are currently west to northwest winds aloft over the Caribbean Sea, providing some wind shear which is typically hostile to the development and intensification of tropical cyclones. But if this wind shear diminishes there are very warm waters in the Caribbean which could add to the fuel of a developing tropical system.

caribbeanseatemps

However, as I always try to point out, the uncertainty is high and there is virtually no skill in long range hurricane forecasts seven to ten days for invest systems like Invest 97L.  There will be doom and gloom forecasts by weather models at these long range.  In some cases the model run might be correct but at this point in time it’s much too early to tell what the impacts will be after the Windward Islands.  Right now most modeling is trending away from U.S. impact and more to Mexico impact.

gefs_invest97l

Climatology would suggest named storms entering the Caribbean during the period 9/20 – 10/10 at low latitudes such as Invest 97L often become major hurricanes, but if it makes a difference there have been 17 “M” named storms since 1950 and none have made U.S. landfall as a hurricane.

If the forecast changes and a U.S threat starts to take shape I will send more updates, but if anyone wants an update just ask.

BMS Tropical Update 9/14/2016 12 PM CDT

I think everyone was surprised to the naming of  Tropical Storm (TS) Julia overland last night at 10 PM EDT. My jaw basically dropped when my iPhone alerted me that the National Hurricane Center (NHC) upgraded investigation area 93L to named storm Julia.
This was a huge surprise for many other meteorologists as well and likely even caught the NHC off guard: Just nine hours earlier they had only given the system 40% chance (image below) and 12 hours prior only a 20% chance of development over the next 48 hours. In fact, the NHC didn’t even classify the system as a depression – the system went straight to a named storm. So clearly, the system developed rapidly by feeding off the very warm waters off the Florida coast.

nhcprob

A look at yesterday 2 pm EDT NHC 5 Day probability of tropical cyclone formation. At 11 PM EDT they upgraded the storm to Tropical Storm Julia

The other surprising fact is that Julia was overland most of yesterday, and it’s really rare for a storm to be named overland. In fact, The Weather Channel’s Michael Lowry reported that only 2% of all tropical cyclones in the Atlantic have formed over land. But according to Philip Klotzbach at Colorado State University, none of the 2% actually formed over Florida, and Julia will go into the record books as being the first named storm to form over Florida and not make landfall.

The other interesting fact is that the NHC barely acknowledged the overland tropical system that will likely have an economic impact above $10 Billons in Louisiana. So the NHC seems to be making up for this mistake by forecasting that Julia will likely also have large flooding impact across the Southeast U.S. and it should have a name like the Louisiana system should have had a name.  It’s possible, but I have been clear that the NHC plays name games with systems, and the storm name (or lack thereof) is less important than the storm impact.

TS Julia will remain overland, quickly weaken today to a Tropical Depression, and park itself over Southern Georgia where it will cause flooding rain (which is likely to be the main insurance impact).

juliarainfallforecast

Tropical Storm Julia Rainfall Forecast showing 2 – 8″ of rain over the next 72 hours over the southeast coast of the U.S.

Tropical Depression 12 just formed near Cape Verde and will struggle to move generally west over the next several days. At this time, is not a threat to the insurance industry. Named storm Karl should be expected later today.

Peak Season

September 10 marked the statistical peak of the Atlantic hurricane season. Based on data gathered since 1851, it’s more likely for a named storm to be active on this date than on any other date in the entire season — from June 1 to November 30. However, this year brought no named storm on September 10. This absence has only occurred in 12 of the past 50 years.
Although Julia’s progression highlights issues with the inconsistency of naming named storm, this year’s count is above normal so far this year. The average date for 11th Atlantic named storm is Nov. 23 and Karl is expected to be named later today. In terms of Accumulated Cyclone Energy (ACE), the basin as a whole is 75% below normal with Hurricane Gaston generating more than 59% of the total ACE this season.

aceasof9_14_2016

As I predicted at the start of the season, storms have struggled to develop in the Main Development Region (MDR) of in the Atlantic Ocean and have developed closer to the U.S. This is due to the large amount of dry dusty air in the atmosphere in this area of the Atlantic basin. This should result in storm having a better chance to form closer to the U.S.

For the Remainder of the Season

The insurance industry should expect more of the same. With warm water, less shear and dry air near the U.S. coastline, conditions are ripe for storm development. The ECMWF ensemble % chance of tropical cyclone development guidance might be the best way to sum up the current and future activity of tropical cyclone activity over the Atlantic Basin over the next two weeks.  As overall I expect less activity over the basin next week as an large scale area of sinking air moves over much of the basin next week.  As of right now besides Julia I don’t expect any U.S. insurance industry concerns over the next two weeks.

wsi_ecmwf_prob

BMS Tropical Update 9/3/2016 9 AM CDT

Hermine is about ready to write chapter four.  Chapter 1 – Unwillingness to develop across Atlantic.  Chapter 2 – Tropical depression in Gulf.  Chapter 3 – Southeastern landfall impacts ending the 10 year Florida hurricane drought.    Now chapter 4 is starting, which should be Northeast impacts.   Like many storms of the past, as storms exit back over the warm waters of the Gulf Stream and the frictional effects of land lessen, storms can easily intensify and over the next 24 hours this is what is expected with Hermine.

Gif Created on Make A GifHowever, it should be noted that this next chapter will not be similar to Hurricane Sandy.   I have seen a few reports that Hermine will be the next Superstorm Sandy, AKA Superstorm Hermine.   This is just a function of the 24/7 weather information era, social media hypecasters, and click bait that is all to common.   Each storm is different and it is easy to lock onto analog storms. I am guilty of doing that often.

However, Hermine is not Sandy, where are many differences between the two storms:

The setup is obviously different .  Sandy came up from the Bahamas and Hermine from the Gulf of Mexico so two totally different directions.

Sandy was a 940 mb low pressure system moving towards the New Jersey coastline with tropical storm force winds 1000 miles across and over 90 mph along the New Jersey coastline.   Hermine will have a low pressure center around 990 mb which is much higher and the tropical storm force winds will only extend out, less than 350 miles according to the latest National Hurricane center forecast.  However, both will likely be hurricanes off the New Jersey shore, but again this depends on how textbook the National Hurricane center is with the classification.

HermineSandy2

Sandy 850 mb winds and mean sea level pressure on the Left.  Hermine 850 mb winds and mean sea level pressure on right.

Sandy’s wave heights were historic at 30ft+   Hermine’s waves are only expected to be 20ft with maybe a few reports of 30ft.

SandyHermineWave

Sandy Wave Height Left and Hermine Wave Height Right.

 

What will make Hermine impactful is this looks like this will be a long duration event. This means waves and wind will batter the northeast coastline for days, not hours like Sandy did.   There is still some track uncertainty and clearly the closer Hermine tracks to the coastline the worse the winds will be.  One can expect, given the long duration of strong winds, minor structural damage could occur.

Currently the Verisk Climate wind model which can be viewed in BMS iVision suggest these tropical storm force winds > 39 mph will not be impacting the New Jersey coastline, but this could change with the next few model runs.

WinddurationSept36z

This will also create coastal flooding problems with some area seeing close to record flooding which will be similar to Sandy along parts of the New Jersey coastline.

Instead of posting various flood forecast along the shore please go to the following site for the latest surge and flood information as these forecasts will change daily. 

At this time I don’t think the new National Hurricane Center storm surge inundation maps are capturing the full impact of the coastal flooding. 

BMS Tropical Update 9/2/2016 12 PM CDT

Hermine made landfall near St. Marks, Florida, around 1:30 am EDT with winds of 80 mph, making it a strong category 1 hurricane at landfall. As predicted, flooding rains, storm surge and tree fall have been the biggest insured impacts and overall should result in a minimal loss for the insurance industry. The storm has now weakened to a tropical storm near Savannah, Georgia. However, as mentioned in previous posts, Hermine will continue to track overland for the next 24 hours and exit the U.S. coastline near the outer banks of North Carolina. Unfortunately however, as we have seen over the last 16 days, the overall energy of this system is persistent. It now appears that Hermine won’t go away any time soon. After Hermine exits the East Coast, it will become a “post tropical” storm. This means that the storm will actually grow in size, and given that the water is as warm as it can possibly get off the East Coast of the U.S., it will continue to fuel Hermine’s circulation.

Below is a look at the warm sea surface temperatures off the East Coast.

Aug31_SST

Rule of thumb: 26C can maintain a tropical system. 28C can easily intensify it.

After Hermine moves off the East Coast, it will likely merge with a large-scale mid-latitude trough which will slow Hermine’s overall movement. Therefore, all but a few of the forecast models suggest that Hermine will stall over a 3-to-4-day period.

ECMWF_Sept2_Ens00z_Hermine

ECMWF ensembles: Most members “Stall” Hermine, some members hook inland, others out to sea. Still some uncertainty watch closely.

Hermine_Sept2_12z_HuModelsjpg

Where Hermine takes turn to North and stalls will be an important factor for Mid-Atlantic impacts. The farther east, the better

 

This is bad new for the barrier islands and beach communities along the Mid Atlantic. Historically high amounts beach erosion will occur with a very constant wind direction for several days. Keep in mind that this constant flow of water will continue to push water into the back bays, and this water will have no outlet. This will result in major coastal flooding, and perhaps even record flooding, along the New Jersey coastline.  The latest extra-tropical storm surge map forecast can be be found here:

njcapemay_Stormsurge

Major to record flooding forecast Sunday night for many stations along NJ coastline. Record at Cape May is 9.0 feet from January Nor’easter. These forecasts will change several times a day and will depend on the track of Hermine.

 

The winds over this 3-to-4-day period will be very similar to a strong nor’easter, and regardless of how the system is classified and where it might wobbles off the East Coast, tropical storm force winds could blow in many areas of the coastline. There is even a chance that Hermine could regain hurricane status. I have already made my point this week that the NHC seems to be treating the hurricane classification as a classroom lecture. Right now, the storm’s classification is far less important than its ultimate impacts.

NHC_WindProb
There are very few storms of this size that have stalled off the East Coast. One of those storms was the Ash Wednesday Storm (1962) and Hurricane Esther (1961), both of which produced significant insured impacts along the East Coast.

 

Esther_1961_track

Hurricane Esther was the first large tropical cyclone to be discovered by satellite imagery. https://en.wikipedia.org/wiki/Hurricane_Esther#New_England

Great video talking about the storm of 1962 and the lessons that have been learned and why one might not see the same type of damage today.

BMS Tropical Update 9/1/2016 12 PM CDT

Historically, Labor Day weekend is no stranger to hurricane impacts to the U.S. Coastline, and this year is no exception. After all, the peak of the season is just ten days away. With winds of 65 mph, Tropical Storm Hermine is less than 10 mph from being classified as a hurricane. And located 170 miles southwest of Apalachicola, Florida and 220 miles west southwest of Tampa, Hermine threatens insured losses. Several models are now coming around to the idea that the long-standing Florida hurricane drought of 3,966 days will soon end. As a reminder, the last Florida landfalling hurricane was Wilma that struck on Oct 24, 2005, near Cape Romano. (You may also recall category 2 Hurricane Arthur, but despite its landfall in 2014, it failed to cause significant insured losses.)

So will Hermine cause large insured losses? Unfortunately, we cannot depend on historical data to help predict since there is little hurricane history in Hermine’s expected path. The three best analog events for the forecasted landfall location are Hurricane Alma (1966), Tropical Storm Allison (1995), and Storm #5 (1941). Storm #5 and Alma were category 2 hurricanes at landfall, so finding a good benchmark historical hurricane to estimated insured loss is difficult in this case, but given these historical events and the hazards outlined below, a multi-million dollar insurance industry loss cannot be ruled out.

The factors that will lead to insured loss at this point will be multifaceted.

Flooding Rains and Storm Surge

Many areas along the Florida Gulf Coast have already seen significant rainfall. Here is what has fallen so far.

RainfallSofar_Hermine
Many areas of northern Florida will see between 3” – 12” more of rainfall through Saturday. And although the forecasted area of landfall is mostly made up of large tidal marshlands resulting in a coastline that is not as densely populated, it is very prone to storm surge.

Storm surge could top several feet in some areas, despite the fact that Hermine will be a minimal hurricane at landfall.  In fact, data suggest Hermine has the kenetic energy of a category 1 hurricane already.

Wind

Using Verisk Climate forecasted wind swath, BMS clients can now better understand wind impacts to specific risks. This high-resolution model wind field shows hurricane force winds rapidly weaken inland due to frictional effect.

iVision_Hermine_VC_WindsSept1

But this does not mean the winds won’t be strong enough knock down some trees, especially given the moist soil conditions in the area. In fact, this section of Florida is not just beach. There are quite a few trees in the north, especially around the Apalachee Bay. When you combine the foliage with the lack of a hurricane activity over the last 10 years, a natural culling of weak and damaged trees and branches can be expected. And, of course, even tropical-storm force winds can cause minor damage to structures.   One also can’t rule out a tornado or twoSoutheast_biomass

 

 

After Florida Landfall
Even though modeling over the last 14 days has not been the best for Hermine, it is starting to come around. Much depends on the track Hermine takes once inland over Florida. If Hermiane tracks back out over the warm waters of the gulf stream, expect Hermine to re-strengthen into a powerful coastal storm. There is some model disagreement about whether Hermine will become a hurricane again, or a post-tropical storm, but regardless, high surf and strong winds will result. Some models even stall Hermine for a few days off the New Jersey coastline near Labor day. The strength really depends upon whether Hermine stays overland along the east coast of the U.S. or just off shore.

Lastly we are still watching Invest 92L  in the Atlantic.  It is fighting dry air and weak so there is no threat at this point in time of development.

Interesting Point
The first Tweet was sent on March 21, 2006, months after Wilma in 2005. Hermine is likely Florida’s first hurricane in the Twitter era.

 

BMS Tropical Update 8/31/2016 12 PM CDT

Update:  12:55 CDT   has officially been upgraded to Tropical Storm .  Because of Aircraft observation from hurricane hunter.  Not because of satellite, ship, or drone observations. 

Tropical Depression (TD) #9
The insurance industry needs to continue to focus on Tropical Depression (TD) #9 which has been trolling the industry for 14 days. It refuses to take the next step to become named storm “Hermine.” If I had a dollar for every time a model suggested a named storm would develop in the next 12 hours, I would be a wealth meteorologist.

This leads me to the next point: the National Hurricane Center (NHC) classification for storms that approach the U.S. coastline have become increasingly technical in recent years. It is bothersome because it has an impact on the insurance industry. Sandy is a recent example of how technical the NHC storm classification has become. Sandy was downgraded from a hurricane to a post-tropical cyclone less than 100 miles from the New Jersey coastline. With TD #9, countless observations many have suggested that TD #9 should have been a tropical storm. In fact, a ship just recently observed winds of 35 kts.

Even the NOAA Global Hawk Drone aircraft that spent 24 hours observing the storm found tropical storm winds.

This bothers me because back in early 1900’s, storms were classified based on simpler information, such as ship observations. There were no drone aircraft or various other heavily scientific equipped aircraft flying into storms to examine the exact center of circulation. The historical catalogs that are used to create today’s catastrophe models have always used ship reports and flooding rain reports from newspapers to suggest a named storm was likely in the area. This was how storms were classified before all this great technology that allowed the NHC to become so technical. This additional technical information skews modern-day historical catalogs from how it would have otherwise been classified, and it could influence catastrophe models understanding of future named storm risks.

However, storm category is less relevant to the insurance industry at this point in time. The industry needs to focus in on impacts, regardless of what category is ultimately assigned to the system in the Gulf. Which is another lesson learned from Sandy, even a non-hurricane can have hurricane impacts. TD #9 will likely have impacts similar to hurricanes as it tracks northeast over the next several days and makes landfall Thursday night somewhere north of Tampa in the Big Bend region of Florida.

09L_tracks_latest09L_intensity_latest

 

Florida Threats
The main threat at this time is heavy rainfall and flooding. Many parts of Florida will continue to experience heavy rain with a 3” – 13” swath of rain predicted across much of northwestern Florida. Flooding is expected in inland areas and coastal areas as well, as the Big Bend region of the coastline is prone to storm surge. The NHC now issues very detailed storm surge forecasts with every advisory.

Adv12_Surge

 

Depending on the strength of TD #9 at landfall, winds may gust strongly enough to cause tree damage and power outages. An absence of recent hurricanes made the area ripe for tree falls. Soil moisture is already above normal for the projected landfall area, and even a weak gust of wind can down unhealthy or overgrown trees. A good natural cleaning of foliage can be expected.

Lastly, along with any tropical system there is always a risk of isolated tornadoes. The northern and central parts of Florida and far southern parts of Georgia are at risk as the center of the system moves across Florida later this week.

BMS clients can preview many of these hazards by using iVision to better understand their exposure to the upcoming event.

Post-Landfall Florida
Some models suggest that after the system makes landfall in Florida, it could hang around off the East Coast and maybe even make a second landfall in the Northeast later next week. But before we examine the storm’s next move, we need it to move to the Northeast from its current stationary location.

BMS Tropical Update 8/29/2016 12 PM CDT

The next three weeks are traditionally the peak of the Northern Hemisphere tropical cyclone season. Mother Nature surely knows as there are now eight tropical systems to watch across the Northern Hemisphere:
• Five are being monitored for landfall over the next five days.
• Four threaten the U.S. coastline.
• Two have been classified as Hurricanes Madeline and Lester, and both are in the East Pacific tracking westward towards Hawaii. Madeline will closely approach the Big Island of Hawaii on Wednesday night, and if the track holds, Lester is forecasted to move past the Big Island on Saturday.
Tropical Depression (TD) #8 is located 210 miles east the Outer Banks of North Carolina and will make close approach to Cape Hatteras, all before turning back out to sea tomorrow night. At this time, no insured loss is expected with this system as tropical-storm force winds are expected to remain just offshore.
TD #9 is our old friend Invest 99L that, after much fanfare last week, took 11 days to develop into a tropical depression. This system still needs to be watched closely as it has the highest potential to impact the insurance industry. Although the upper air conditions (Strong Wind Shear) are not ideal for hurricane development, the sea surface temperatures are very warm off the west coast of Florida. TD #9 should be a named storm later today.
As a result of a cold front that will provide cooler weather over much of the East Coast for the long Labor Day weekend, this will also allow the system to turn to the northeast and lead to a track that will cross northern Florida with landfall in the Great Bend region on Thursday. Thereafter, the track calls for the system to accelerate out to sea off the coast of the south-eastern U.S. TD #9 is expected to continue slight strengthening as it curves northeast in the eastern Gulf of Mexico in the next 36-48 hours. It should be noted that this system has a history during which multiple models over-forecasted storm intensification. Now, based on the current intensity ratings issued by many of the forecast models, the NHC seems to have opted for a more conservative forecast. Below are the current NHC’s chances of winds reaching tropical-storm force in the next 5 days, which are 30% or less at individual locations in Florida.

TS_WindProb_Aug29Aug2912PM_99LForecastedIntesnity

 

The biggest impacts to the insurance industry would be tropical storm force winds, which could include minor damage and tree fall damage. Rainfall is expected to be 3” – 6” across much of Florida over the next five days so localized flooding is possible.

Lastly invest 92L  is coming off of Africa and has a 40 – 50% chance of development over next 10 days and is expected to track toward the U.S. coastline similar to invest 99L over the last 11 days.  Let’s hope the drama around invest 99L last week does not lead the insurance industry to disregard the next threat as we approach the peak of the season September 10th.

CrCwdovWcAATAwV

BMS Tropical Update 8/25/2016 12 PM CDT

In the past six days the insurance industry has waited and watched for tropical wave Invest 99L to develop into a named storm. Frankly, it’s getting tiresome.

Six days ago at this time many models predicted Invest 99L would become a full named hurricane.

99L_GFSAug19th

Above is the 00z run of the GFS model on August 19th valid for this coming Monday, August 29th, which had Invest 99L at a category 5 hurricane as it safely re-curves away from the East Coast.
It is all but certain this scenario will not play out, and once again, it reemphasizes the point that there can be large model errors that exists in hurricane forecasting. In fact, this reminds me of my February presentation at the Reinsurance Association of America Cat Modeling conference on HypOcane. This presentation examined the large forecasting errors associated with Erika and Joaquine in 2015. These errors led to unnecessary hype due to the over-reliance on numerical models. We can’t forget that forecasting tropical systems it not an exact science. The track errors are improving for named storm forecasting, but intensity forecasting still remains a challenge. Invest 99L highlights these challenges as some models suggested six days ago that there would be a tropical system nearing the Bahamas; however, the intensity guidance was all over the place as shown in the scenario above.

99L_ECMWF_Guidance

Last 9 ECMWF track forecasts for Invest 99L. The two Gulf coast landfalls were 8-day forecasts and were highly uncertain. This option is still on the table.

 

99L_GFS_Guidance

Last 26 GFS track forecasts for Invest 99L. All but two focused on Florida. The last few model runs of the GFS model have hard time tracking Invest 99L.

NOAA hurricane hunters continue to find a poorly organized tropical wave southeast of the Turks and Caicos Islands. There are times where tropical-storm force winds have been observed, but a lack of a well defined center of circulation with convection continues which is needed for named storm status. This could change at any time.
So for now, it is the same old story: there is a chance of a storm developing, and conditions west of the storm are ripe for development due to very warm sea surface temperatures, less dry air aloft and lower wind shear environment.

What we know today about Invest 99L:
• Models slow the forward speed of 99L late this weekend into early next week. This lessens the chance that the system will move into the western Gulf of Mexico, and increase the chances the system will move into eastern Gulf of Mexico.
• If a named storm develops, Louisiana/Mississippi/Alabama landfall cannot be ruled out, but models suggest Florida is at peak risk.  Time is however running out as the system tracks closer to Florida.
• Most models provided poor intensity guidance. If the system is ultimately named, hurricane development can not be ruled out due to the warm sea surface environment in the forecasted path of the system.

For the latest track and forecast information please visit:

http://www.tropicaltidbits.com/storminfo/#99L