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BMS Tropical Update 10/6/2016 10 AM CDT

Summary

  • Matthew is a weak category-4 hurricane and will likely slowly strengthen today as passes over Nassau, Bahamas.
  • Matthew will likely make landfall between Jupiter, Florida, and West Palm Beach, Florida, as a category-4 hurricane. Landfall should weaken Matthew to a category 2 by the time it reaches Daytona Beach, Florida, and then travels up the coastline. I don’t anticipate that the center will track more than 10-20 miles inland.
  • There is a very small chance that Matthew will become a category 5 hurricane before it reaches the Florida coastline, as it will likely strengthen until its inner core starts to interact with the Florida coastline.
  • Estimating the maximum storm surge is a bit complicated as these forecasts depend on Matthew’s track and strength as it travels up the Florida coast. If Matthew weakens due to land interaction, surge will be less severe; but if Matthew stays off shore, more water may move onto the coast, and this surge could be further complicated by multiple tide cycles that are expected during Matthew’s move up the coastline.
  • Given the large amount of exposure along the coast and expected wind gusts of 144 mph, this will no doubt be a significant insured loss event. For specific impacts, each National Weather Service (NWS) office is offering detailed forecasts for Matthew.
  • In the longer-range forecast, Matthew will likely loop over or the stall off the southeast coast this weekend or early next week. This will limit insured losses in locations that are north of South Carolina.

Forecasted Landfall Location and Specifics
As I have mentioned, Matthew is tracking over very warm water in the Bahamas. This warm water will continue to fuel Matthew until it starts to interact with the Florida coastline tomorrow morning. Keep in mind that hurricane-intensity forecasting is typically more predictable than hurricane-track forecasting. Matthew already surprised us this past weekend with rapid intensification to a category-5 hurricane in the southern Caribbean. It should be noted that, currently, no model guidance is forecasting further rapid intensification.  The intensity guidance below show most models are in the camp that Matthew will be category 4 hurricane at landfall or along the Florida coastline.

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With Florida land interaction expected in the 36 hours. The intensity of Matthew should weaken considerable especially if it tracks inland a bit vs staying over open water.

For the last week, meteorologists have used the long-range hurricane models to predict Matthew’s track. We are now within what is considered the short-term forecast window where higher-resolution weather models become a bit more useful for providing specific hurricane forecasting.
HRRR (High Resolution Rapid Refresh) is a high-resolution (3K grid resolution) model which shows the details of a hurricane and its impacts. This model is updated hourly and forecasts the next 18 hours. Here is the latest hourly forecasts.

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My general expectation is that Matthew will make landfall and track inland 10-20 miles along interstate highway 95. This counters some high-resolution models that suggest Matthew will track along the Florida coastline. Three of these models are the HWRF, GFDL and Verisk Climate model (which is the basis for BMS iVision).

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HWRF Forecasted Wind Swath. This is not surface wind speeds These are winds at 900 mb which close to the surface.

 

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GFDL Forecasted Wind Swath. This is not surface wind speeds These are winds at 900 mb which close to the surface.

 

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This is the National Weather Service (NWS) Forecated wind swath

 

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BMS iVision Verisk Climate wind swath which is a version of the WRF model. Users of iVision can use this product to get an ideas of risks impacted by wind speed.

One important point I want to make is no numerical weather prediction model is at a high enough resolution to resolve the details of surface roughness. It is this surface roughness that would likely weaken the winds inland. So many of the modeled forecast plots above are likely overestimating the wind speed. This is particularly apparent in the National Weather Service forecasted wind swath.

At this time, much can be gleaned from the various NWS forecast products because they offer great detail on potential impacts. These details include likely power outages, specific areas that are prone to flooding, tornado threats, etc. Many of these NWS offices offer public video briefings as well. In some cases the wording is quite strong, and for good reason, as Matthew is a dangerous, life-threating storm.

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Estimating the maximum storm surge is a bit complicated as these forecasts depend on Matthew’s track and strength as it travels up the Florida coast. If Matthew weakens due to land interaction, surge will be less severe; but if Matthew stays off shore, more water may move onto the coast, and this surge could be further complicated by multiple tide cycles that are expected during Matthew’s move up the coastline.  Please utilize the new NHC storm surge forecast guidance. This guidance will change with the NHC track forecast. Right now the worse storm surge will occur in north Florida where the continental shelf extends out into the Atlantic and water will have more time to pile up.  Surge values in this general area could be greater than 9 feet in isolated locations.

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Storm Surge Forecast For Jupiter, FL

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Storm Surge Forecast For St. Augustine

 

Another issue that is not being talked about much is the possible flooding of Lake Okeechobee. The lake level is very high right now at 15.78 feet.  A  risk of flooding starts to occur if this lake reaches 17″. If the lake level goes up to 20″ this could be a major concern as this is a known dike that is dire need of upgrades and if given to much stress it could break if water levels get too high. Matthew will no doubt raise this lake level.   The Weather Channel has a good summary  of the risk.

Long Range Forecast

As we have seen for over the last week, Matthew’s long-range forecast remains uncertain. But the chance of significant insured loss at locations north of South Carolina is declining. Many global models suggest Matthew will loop off the southeast coast. Some of these model solutions even take Matthew back into the Bahamas or Florida, and in one extreme case, back into the Gulf of Mexico. Most likely, Matthew will sit and stall near the southeast coast and weaken while doing so. Matthew will eventually be kicked out into the Atlantic Ocean. However, as with any long-range hurricane track forecast, a lot of variables are at play, so Matthew’s long-range tracking still requires watching.

 

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The newest ECMWF forecast which has shown the best skill in the long range 3+ day range

 

 

BMS Tropical Update 10/5/2016 11 AM CDT

Summary

  • Matthew has weakened slightly due to interaction from Cuba and Haiti yesterday and is currently still a weaker Category 3 hurricane 115 miles south of Long Island Bahamas. However, it will only take 12 – 24 hours to regain strength into a stronger category 3 or 4 hurricane as it nears the Florida coastline.
  • Wouldn’t it be something if a major hurricane comes within miles of the Florida coastline and the major hurricanes drought lives on?  How about the fact than that the last two major hurricanes to impact the U.S. never made landfall?  This is still an option as some models keep Matthew from making landfall and other models have it making landfall in Florida.    I have no change in the analog storms provided in yesterday’s update as it relates to southeast impacts.
  • When a hurricane is forecast to take a track roughly parallel to a coastline, as Matthew is forecast to do from Florida through South Carolina, its impact can vary greatly depending on this final track. A small deviation of the track to the left of the NHC forecast could bring the core of a major hurricane onshore, while a small deviation to the right could keep all of the hurricane-force winds offshore.
  • Depending on location some parts of the southeast have been fairly wet over the last 30 days. This could amplify the inland flood threat and increase tree fall where the ground could be saturated.   As much as 5 to 7 inches of rain is forecasted for coastal areas of the southeast.
  • There is still uncertainty in the long range forecast. As mentioned almost a week ago there is a chance Matthew would do a loop off the southeast coast.  More and more model runs are coming around to this idea.  This decreases the threat to northeast impacts late this weekend and into next week.  However, this increases the chances that the Bahamas or even Florida could see a second landfall from Matthew.  Rising issue of hour clauses and what part of the storm caused the loss if this scenario occurs.

Expect Strengthening

As expected Matthew has weakened slightly due to interaction from Cuba and Haiti yesterday.   However, as stated almost a week ago the water along the forecasted path of Matthew is very warm and should allow for Matthew to strengthen as it moves closer to the Florida Coastline.  I was also expecting Matthew to grow in size as currently the hurricane force winds only extend out 40 miles from the center of Mathew.  Depending how far off shore Matthew stays will determine the strength of the hurricane north of the Bahamas.  If Matthew stays off shore I still see no reason why Matthew would not become larger and stronger than the current NHC forecast.

 

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Tropical Cyclone Heat Potential highlighting the water over the Bahamas is near the top of the scale. Lots of energy for hurricane growth.

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Current Hurricane Matthew Intensity Guidance

 

Tricky impact forecast

As you might imagine the overall impact of Matthew on the southeast coastline will depend ultimately where it tracks along the coast or if it makes landfall.  The NHC sums up the overall uncertainty here in its key messages.

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To illustrate the point let’s take the current NHC forecast point near West Palm Beach, Florida, and shift an illustrated impact area 10 miles on either side of that point.  As you can see the overall track of the storm makes a big difference.

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Image credit Bryan Wood

There is still a risk of storm surge potentially affecting certain coastal locations. Overall, the Atlantic side of Florida has a steep shelf offshore which tends to protect the coastline from large surge.  However, wave action could be a concern given the lack of beach area along the east coast of Florida.  As stated yesterday the direction of Matthew to the north will also mitigate the most significant of surge threats but this threat increases in northern Florida and in Georgia and the Carolinas.  Again, like wind impacts, the surge impacts are dependent on the size of the storm, the intensity, and the track.

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Latest 3 sec wind speed swath in BMS iVision

Other impacts to think about

With the understanding that it’s been a long while, over 10 years, since a major hurricane impacted Florida and in some cases a major hurricane has never impacted parts of Florida.  This means the overall foliage is likely over grown and needs a good cleaning.   It is Mother Nature’s job to do this and if it has not been done in a while this can surely increase insured loss. We can also look to see if tree fall has a higher likelihood of occurring due to wet soil conditions.     Some parts of the southeast have been fairly wet over the last 30 days. This could amplify the inland flood threat and increase tree fall where the ground could be saturated.   As much as 5 to 7 inches of rain is forecasted for coastal areas of the southeast.

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Rainfall over the last 30 days for the Southeast U.S.

 

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Departure from normal of this rainfall over the last 30 days. In some locations the rain might be a welcome sight as it has been dry.

 

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NOAA Seven Day Rainfall Forecast

 

Northeast impact or Loop?

With any hurricane forecast there uncertainty in the long range forecast.  As mentioned almost a week ago there is a chance Matthew would do a loop off the southeast coast.  More and more model runs are coming around to this idea.  This decreases the threat to northeast impacts late this weekend and into next week.   It is still too early to have complete confidence in this shift.  However if this does occur maybe we will have yet another example of a hurricane that loops.  This would also increases the chances that the Bahamas or even Florida could see a second landfall from Matthew.  Rising issue of hour clauses and what part of the storm caused the loss if this scenario occurs.

A large GIF annimation of 00z GFS 240-hr forecast at full-res 13-km showing surface wind speed.

http://weather.graphics/gfs_2016100500_uv10m_s_watl.gif

 

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BMS Tropical Update 10/4/2016 11 AM CDT

Summary

  • Matthew will cause U.S insured loss based on current analog tracks.
  • Matthew will be a major hurricane as it tracks along the East Coast of Florida up into North Carolina.
  • The NHC still does not see this as a major hurricane impacting North Carolina, but I do if the storm stays off shore.  I still also expect Matthew to grow in size to a much larger hurricane than it is now.
  • Matthew still has a chance  at making a Florida landfall as surface friction could get pulled in.
  • Matthew will no doubt be a devastating hurricane for Haiti and the Bahamas.
  • It’s been nearly four years since the last Tropical Storm Watch has been issued for south Florida. This has now issued by the National Weather Service hurricane warning and evacuations could soon follow.

Time to start talking U.S. Insured Impacts

*The impacts below are for the current NHC forecast track which keeps Matthew off the coast of Florida as it tracks up the east coast of the U.S for the next five days.   Here we mostly focus on Florida impacts.

 

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Current NHC forecast in iVison

The first thing to consider in terms of wind impacts will be to understand that the strongest winds in a hurricane in the northern hemisphere occur on the right side of the storm. On the right side of the hurricane the winds also extend out from the center the furthest.   On the left side of a hurricane the winds extend from the center of a hurricane less and the winds can be slightly weaker.   Since Matthew is forecasted to track up the East Coast of Florida the weaker side of the hurricane will be impacting the coastline.

Clearly the closer Matthew tracks to the coastline the higher the wind impact might be. Also if Matthew grows in size, as I expect it to do, the impacts could be worse.  Given the current forecasted track by the NHC generally hurricane force winds would only be experience right at the coastline and tropical storm force winds would extend at most 20 – 40 miles inland.

To aid in understanding wind impacts BMS clients have access to Verisk Climates custom hurricane wind field forecast.   This is just one forecast of many and is subject to the same errors of other forecast model output, but users can get an understanding of how winds impact their portfolio.

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Current Verisk Climate Modeled windfield in iVison. This forecast is just one of many forecasted tracks Matthew could take over the next few days.

Storm surge will be an issue for the entire coastline as the storm moves along the coast of Florida, but since the storm will parallel the coastline the surge would not be as bad if the storm were impacting the coast in a perpendicular direction.  Here is a link the the NHC current storm surge guidance. Of course inland flooding could also be a concern with a large amount or rain falling over a short period of time.

Depending on coverage wording Business Insurance (BI)  losses could result due to evacuations.  The last time a storm tracked up the east coast (Floyd 1999) it caused a massive evacuation of the Florida Coastline.  As the storm turned to the north across the Bahamas, a progressively larger area of the Florida coastline was threatened. It is estimated that Floyd was at the time the largest peacetime evacuation ever in the U.S., with around 2.6 million evacuating coastal areas in Florida, Georgia, and the Carolina’s.

Analog Events

I have spent a good amount of time going year by year to find a good set of matching analog historical storms that took a similar track to Matthew’s.  There is no perfect fit as every storm is different, but the following storm can help insured understand what impacts might occur to their portfolio of risks.  Estimated insured losses from historical events is not an exact science, there are known changes to wealth, population, etc, but the normalization of these damages can help compare losses if they all struck land today. This research has been carried out by Pielke Jr. et al 2008 and have been adjusted by BMS to account for insured loss.

Floyd in 1999 tracked up the east coast of Florida as a category 3 / 4 hurricane and made landfall in North Carolina as a Category 2.   Floyd at the time caused $50m in insured loss to Florida and today would cause an estimated 4.8B in insured loss to other east coast states.

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Hurricane Floyd 1999 Track

David 1979 could also be used as an analog event but the storm tracked very close to the Florida coastline, closer than Matthew is forecasted to.  David was also only a category 2 along its path.   It is estimated that David would cause 1.6 billion of insured loss to Florida and Georgia in today’s dollars. Clearly a stronger hurricane along its path this close to the coastline would cause higher losses.

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Hurricane David 1979 track

An older analog that actually made landfall in Florida would be Unnamed Storm 1 1926 (Different then the Great Miami Hurricane of 1926) Today this storm would cause 3 Billion in insured loss today.

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Hurricane Storm 1 1926 – Track with Florida landfall which is still an option.

Could Matthew make U.S Landfall?

Currently the NHC official forecast keeps Matthew off shore as a major hurricane with a landfall in the Outer Banks of North Carolina.  However, there are still several forecasts that result in a landfall either in Florida, Georgia, or South Carolina and these states are still in the cone of uncertainty.   The exact location of a landfall or track won’t be known for another day or two.   If Matthew tracks close enough to land frictional effect could pull the storm inland, but given Matthew is forecasted to move at a slower speed this effect is less likely to occur. As we have seen there is a consistent westward shift in model tracks and if this occurs the landfall possibilities will continue to increase.   There is a 80% chance the coastline of Florida will experience tropical storm force winds.  The chances of Florida experiencing hurricane force wind speeds is 30%.

It should also be noted that some model runs still stall Matthew off the North Carolina coastline which add to the forecast complexities in the long term.  At this time northeast impacts appear to be limited as Matthew would stay out at sea.

 

BMS Tropical Update 10/3/2016 11 AM CDT

Summary

  • Matthew continues to be a powerful category 4 hurricane 275 miles SW of Port Au Prince Haiti.
  • Matthew will be a devastating hurricane for Haiti and the Bahamas.
  • It should not be surprising if Matthew become a category 5 hurricane near Haiti and Cuba.  Little weakening should be expected from the higher topography as  Matthew  tracks between Haiti and Cuba.
  • NHC is still under-forecasting the overall intensity of Matthew north of the Bahamas and I don’t see any reason why it would not be a major hurricane north of the Bahamas.
  • Although Matthew is a small size hurricane at this time, hurricane force winds extend 30 miles from the center and tropical storm force winds extend 195 miles from center.  Matthew’s size should grow in extent north of the Bahamas, increasing wind related impacts.
  • Matthew’s forecast model guidance has shifted to the West closer to the U.S. overnight. This increases the probability of U.S landfall.  This even increases the threat of a Florida landfall or impacts.  But at this time over the next week the highest U.S. landfall probability is North Carolina and the Outer Banks.
  • Still an option on the table is that Matthew could stall off the Southeast coastline and not turn out to sea.  There are a lot of options on the table north of the Bahamas as the forecast has a large amount of uncertainty still.

Matthew Size and Strength to the North

Yesterday I pointed out how small Matthew was, but already today the size of hurricane force winds has doubled to over 30 miles from the center of the storm.   I expect the size of Matthew to get much larger as it tracks north particularly in the Bahamas and points North.

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HWRF forecast for Sat Oct 8 showing a much larger windfield as Matthew moves northward.

I still feel the NHC is too weak on its intensity forecast North of the Bahamas.  Besides wind shear there is nothing preventing Matthew from becoming a major hurricane north of the Bahamas as the waters off the east coast are above normal temperature and can support a stronger hurricane.   This also means as the track of Matthew shifts closer to the U.S. expect a higher insured impact even from a bypassing storm.

U.S. Threat Increasing

Over the weekend the U.S landfall probability was fairly steady.  However, with the northward turn of Matthew and the huge amount of data now flowing into the global weather models from extra weather balloons and aircraft the models might be getting a better handle on the future track of Matthew.  In fact, over night the threat has increased for the U.S. and a U.S. landfalling hurricane is not off the table.  There is still a probability of this occurring even in Florida. The North Carolina Outer Banks have the highest probability of landfall at this time, but there can be high insured impact even if the storm bypasses the U.S coastline.  Remember Floyd in 1999 never made a Florida landfall, but caused 50 million in insured losses at the time.  In total as Floyd moved up the U.S coastline it’s insured impacts would be equivalent to a 4.5 billion dollar insured loss today.

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1999 Hurricane Floyd track up the East Coast of the U.S.

The probability of a U.S landfall has increased from 35% to 45% probability as the overall guidance has shifted to the west toward the U.S. coastline with a 55%  likelihood Matthew will staying out to sea beyond the Bahamas.  However, as stated since last week, it is a complicated forecast with lots of options on the table.  The ridging in the central Atlantic seems to be increasing which is likely going to continue to force Matthew westward a bit. Some models even merge the newly designated Invest 98 which is currently a broad area of low pressure located about 400 miles northeast of the northern Leeward Islands.

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As I talked about last Thursday, there was a chance Matthew might stall off the southeast coastline, this option is still on the table and last night’s ECMWF model shows this in the red line in the ECMWF ensemble forecast below.

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ECMWF forecast in red. Shows Matthew stalling out. The NHC official forecast shown in black line. 51 individual ECMWF forecast shown in gray lines many with Florida landfall which cannot be ruled out.

BMS Tropical Update 10/2/2016 10 AM CDT

Summary

  • Matthew is still a powerful category 4 hurricane 340 miles southwest of  Port Au Prince, Haiti.
  • Matthew is a very small storm with hurricane force winds only extending out from the center 25 miles.
  • Matthew’s impact to Haiti will be devastating.  Flooding rains and a rare hit from the south will make this a unique event.
  • Forecast track guidance has been shifting eastward over the last 24 hrs
  • Florida landfall threat appears to be off the table with only a very small probability at this time.
  • Less weakening from higher topography is now forecasted as Matthew passes between Cuba and Haiti.
  • North of the Bahamas, Matthew is still expected to be a major hurricane.
  • Beyond the five day forecast, models are still playing the game of back and forth with the forecasted track north of the Bahamas.  There is no change in the landfall probabilities from yesterday which still stand at a 35% probability of US landfall during the course of Matthew’s trek north and a 65% likelihood of staying out to sea beyond the Bahamas.  It should be noted that the forecast is still complicated and any northeast landfall is still a week away.

Matthew  Impacts

Matthew has now finally turned North and is moving at a northwest direction at a slow speed 5 mph. Matthew’s smaller size storm might be one of the only positives of a major hurricane hitting Jamaica, Cuba and Haiti.  Currently Matthew’s eye is only 12 miles across and hurricane force winds only extend out from the center 25 miles.  Matthew will continue to grow in size as it moves northward, but its small size should keep overall wind damage at a minimum as the strongest winds (Right side of hurricane) hit Haiti.

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The biggest impact to Jamaica, Cuba and Haiti will be flooding rains.  Up to 40” of rain is forecasted over Haiti which will be devastating for this poorly developed country.  Overall insurance penetration is low in Haiti and many areas are still recovering from the devastating 2010 earthquake.

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It should be noted this is rainfall from yesterday forecast. Today’s has not been posted yet, but I expect similar amounts

Over the last 24 hours the official NHC forecast track has been shifting eastward. This means less impact to Jamaica and more impact to Haiti.  This also decreases the overall probability of any Florida impacts to the insurance industry.

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Past 24 hours of NHC Official forecast tracks. The darker the color the more recent the forecast track.

The track northward in-between Haiti and Cuba will limit the impact of higher terrain.  This rare southern side impact will result in a rare impact for Haiti and will lead to issues of storm surge not usually seen on the southern bays and inlets.

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No Category 4 hurricane as come up from the south in this part of the Caribbean Sea.

Beyond 5 day Forecast

Forecast model guidance and very warm sea surface temperatures along the east coast of the U.S. will allow Matthew to maintain its major hurricane status north of the Bahamas and possibly north of North Carolina.

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Most model guidance maintain a major hurricane for the entire forecast period.

Beyond the five day forecast, models are still playing the game of back and forth with the forecast track north of the Bahamas.  There is no change in the landfall probabilities from yesterday which still stand at a 35% probability of US landfall during the course of Matthew’s trek north and a 65% likelihood of staying out to sea beyond the Bahamas.  It should be noted that the forecast is still complicated and any northeast landfall is still a week away.  Below is a look at the WSI calibrated hurricane risk products from the GFS and ECMWF models suggesting a 50% chance Matthew will make U.S landfall.  My probability is lower at this time which is more inline with the current NHC official forecast.

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GFS hurricane risk.  Over 60% chance U.S. will see hurricane landfall.

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ECMWF forecast suggesting U.S has a 50% chance of hurricane landfall.

BMS Tropical Update 10/1/2016 11 AM CDT

Summary

  • Matthew is very powerful category 4 hurricane 390 miles southeast of Kingston, Jamaica and the second major hurricane of the 2016 Atlantic hurricane season.
  • No one – I mean NO one forecasted Matthew to rapidly intensifying into a category 5 Hurricane yesterday. This just goes to show how much work still needs to be done in the science of tropical cyclone forecasting especially for intensity.
  • Matthew has ended a 9-yr drought between category 5 hurricanes. The last category 5 hurricane in the Atlantic was Hurricane Felix.   It should be noted that this was the longest period in-between Atlantic Category 5 hurricanes since the period between the 1938 New England hurricane to 1953 hurricane Carol.  Another interesting fact is that Matthew was at category 5 about 30 miles from where Felix was a category 5.
  • Matthew should level off in terms of intensity, but a strong major hurricane is still expected as Matthew turns northward.
  • Beyond the five days forecast, models are trending east or west with every other run. Its a bit of back and fourth at this point.  However, I can finally provide a few ideas on landfall scenarios. There is currently a 35% probability of US landfall during the course of Matthew’s trek north and a 65% likelihood of staying out to sea beyond the Bahamas.  It should be noted that the forecast is still complicated.

Next Few Days

As predicted all week today is the day that Matthew should start to take a right turn and move into the central Caribbean.  This will then help determine where and when Matthew  tracks along the eastern U.S. seaboard. While many details remain unresolved in regards to Matthew’s future track, there are still indications that Matthew could impact the northeastern states at significant amplitude sometime between October 10-12. The purpose of this blog is not to HYPE but rather show an objective model analysis to illustrate risk and give all scenarios that are on the table at this time.

The National Hurricane Center is still showing Matthew make a right turn and track over the weekend as a Category 3 major hurricane, which increases the risk for significant impacts across areas including Jamaica, Cuba, and Haiti from the south which is a bit rare direction for a hit for these islands This could increase wind loss given most building / trees have not seen this unique wind direction. Storm surge could also be an issue in some of the southern bays which usually don’t see a storm from this direction.

Matthew will likely weaken as it crosses Cuba, Jamaica, Haiti, where intensities should drop to a Category 2 hurricane. After this one might notice that the latest NHC forecast now expect Matthew to be a major hurricane in the Bahamas.

There is no reason why Matthew should not  be a major hurricane as it track northward north of the Bahamas as it feeds off the above normal sea surface temperatures here.

East Coast Scenarios

Florida landfall is still on the table but at a lower probability at this time. However, this would be a decent insurance industry loss event as category 2 maybe category 3 impacts.

Matthew impacts Bahamas as a major hurricane and with a northward movement that could allow for an initial landfall across North Carolina’s Outer Banks sometime late next week or weekend (looking like Saturday, October 8) as a category 3 or 4 major hurricane, though the storm could also stay just offshore.  From there models show a northward track toward the northeastern states.

The most likely scenario at this time is the “Out to Sea” and no impact to the East Coast of the U.S.. Of course this would be the best scenario for insurance company.

Worst Case Scenario

Last night run of the American GFS model surely takes home the award for the worst case scenario so far of all the model runs I have seen.    (Again not HYPE and just one model solution of many and this one scenario is highly unlikely at this time)

The select sequence of this model runs below would rival the immortal hurricane Donna of 1960. In this scenario Matthew would do the unbelievable and allow hurricane force winds in every state from Florida to New England as Matthew tracks just off shore.

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Florida Hurricane Force Wind From GFS 00z Model Run

 

 

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Georgia Hurricane Force Wind From GFS 00z Model Run – Friday Oct 7th

 

 

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South Carolina Hurricane Force Wind From GFS 00z Model Run – Sat Oct 8th

 

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North Carolina Hurricane Force Wind From GFS 00z Model Run – Sat Oct 8th

 

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New Jersey Hurricane Force Wind From GFS 00z Model Run – Sat Oct 8th

 

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New England Hurricane Force Wind From GFS 00z Model Run – Sat Oct 9th

Again this scenario is one of many and highly unlikely.  The ECMWF ensembles model is more off shore today but overall the forecast is complicated next week. The newest 06z GFS ensembles are east of the worst case scenario shown above.

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Above is the latest ECMWF model track guidance from the ensemble forecast

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Above is the latest GFS model track guidance from the ensemble forecast

It should also be noted that the ECMWF has been performing better than the GFS thus far with Matthew.

Current Probability

Based on the current model guidance there is currently a 35% probability of US landfall during the course of Matthew’s trek north and a 65% likelihood of staying out to sea beyond the Bahamas.  It should be noted to keep this short I have not explained why this is still complicated forecast. There are a lot of moving parts and more will be known today once Matthew takes that turn north and we get an ideas of the forward speed north.

 

BMS Tropical Update 9/30/2016 11 AM CDT

Summary

  • Tropical Storm Matthew is very close to becoming a major hurricane as it is 495 mile southeast of Kingston, Jamaica.
  • Matthew has intensified over the last 24 hr.    This was not forecasted to occur given the storm is still undergoing 20 kts of southerly wind shear.   Matthew is defying the odds and feeding off the warm Caribbean Sea waters we have talked about.
  • We have seen the NHC shift their track westward closer to Jamaica and they now have Matthew as it hits Jamaica.
  • The NHC still does not have Matthew as a major hurricane impacting the Bahamas.  I think they will change this guidance upward with a major hurricane in the Bahamas middle of next week.
  • The NHC cone of uncertainty is now closer to Florida so a Florida landfalling hurricane cannot be ruled out in the middle of next week.

What has changed in last 24 hrs

Matthew has intensified steadily over the last 24 hours and is very close to becoming a major hurricane. This is a bit of a chance in forecast as this increased intensity was not supposed to happen until it turned northward.  The idea that Matthew will be a major hurricane as it turns north toward Jamaica and Haiti is now in the NHC forecast guidance and along the thinking of yesterday BMS tropical update.   Matthew could still weaken due to interaction of the high mountains of Jamaica and Cuba on its way northward on Tuesday next week.  However, Matthew should rapidly regain its strength as a major hurricane over the Bahamas on Wednesday and Thursday next week.

Over the last several days we have seen the NHC track guidance shift westward.  It would appear this shift westward in track will now start to be consistent with a major hurricane hitting Jamaica.   What makes this interesting is very few major hurricanes in history have hit Jamaica from a southern direction so this could increase the insured loss on the island given an unusual wind direction for a major hurricane.

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The NHC forecast brings Matthew near Jamaica as a major hurricane. Here’s the tropical systems to pass/hit Jamaica at Major Hurricane intensity. Interestingly, almost all of these tracks are more east-to-west vs. the expected south-to-north path that Matthew looks to take.

The ideas of Matthew weakening slightly due to the higher terrain of Jamaica, Cuba and Haiti is still on the table but I expect Matthew to rapidly strengthen again as it moves over the Bahamas on Wednesday next week.

Long Range Track Guidance Uncertainty

There are many possibilities that remain in play and there is not enough information to make a skillful assessment of ultimate outcomes at this time.  Possibilities are wide ranging from a track into southern Florida, an East Coast US landfall or even potentially out to sea into the Atlantic.  Over the past 24 hours there is some shift away from the Gulf of Mexico scenario and more towards a Florida US landfall or out to the Atlantic.

 

In terms of specific impacts north of the Caribbean, it’s too early to speculate on ultimate outcomes with Matthew until more information is available to make a skillful forecast.

In general the forecast models have still been shifting westward and the NHC has the edge of “cone” now grazing South Florida.

As we go into the weekend my general thoughts of Matthew impacting points along the Northeast coast later next week have to do with what the forward speed of Matthew might be once it starts it turn northward.  This will need to be watched very carefully.   The faster it comes north the better the chance it can reach the North Carolina coast before turning out to sea. If Matthew is slower coming out of the Caribbean it would likely have a better chance to be turned out to sea.  Also in the long range the option of turning out to sea is greater given the upper level pattern in the image I have provided below you will see the ridge (orange red colors)  is in a southwest – northeast direction as opposed to a northwest southeast direction which leave an option for Matthew with a way out to sea vs turning back into the northeast similar to Hazel and Sandy which had a different ridge configuration.

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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.

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Forecasted Track

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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.

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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.

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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

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ECMWF Ensemble Long Range Forecast Tracks for Matthew

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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.

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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.

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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.

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

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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.

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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.

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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.

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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.