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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.