One For The Record Books
It appears that the global models have a common case of the flip-flops over the last 48 hours, which is typical with a complex forecast situation. We are also seeing some of the history books on hurricane intensity being rewritten. Based on information received from Phil Klotzbach at Colorado State University, Irma has now had a maximum wind of 180 mph+ for the past 24 hours, which is an Atlantic Basin record in the satellite era. This is just one of the many records Irma is breaking, and unfortunately it’s not done yet as it is still a Category 5 hurricane.
Caribbean Islands take a direct hit
Irma crossed several Caribbean islands overnight and is now moving in a slight west-northwest direction at 16 mph, placing it very near the U.S and British Virgin Islands. The damage I have been seeing across social media on many of these islands is heavy. This is to be expected from a Category 5 hurricane, as even some of the strongest buildings can sustain damage.
Below is a once in a lifetime sunrise as the northern Caribbean islands of Angulla, Saint Martin, Sint Maarten and St. Barts saw daylight break in the eye of the most powerful hurricane to impact these islands in recorded history.
Model Flip Flop and Irma’s Future Track
As we continue to watch Hurricane Irma strengthen and shatter the record books on intensity, the question of where Irma will go this weekend is still hanging in the air. It’s all about the turn north, but when and where will that occur?
As I have been saying since Friday, a potential turn north all has to do with a weakness in the Bermuda high that will develop as a result of the passing of an upper level trough of low pressure on the East Coast. This turn north is very critical in determining Irma’s future track and any resulting impact to the U.S. insurance industry. This past weekend, we saw a lot of model guidance suggesting the possibility of Irma tracking up Florida’s east coast. On Monday and earlier Tuesday, the general model guidance was suggesting that Irma might track closer to the Florida Keys. As of last night and this morning, the model guidance is back to suggesting that Irma could track up Florida’s east coast. This is a classic case of model flip-flop in a very complex weather pattern, and the west and east coasts of Florida are still very much on the table as potential tracks for Irma. However, as I talked about yesterday, if you forecast with the trend, the trend is currently moving towards a track up the east coast of Florida.
The image above is the latest water vapor satellite image of North America. In this image, note the area labeled key polar shortwave. This is the shortwave that needs to be watched very carefully. This disturbance is forecasted to dive rapidly into the Mississippi River Valley within the next three days. The timing of this shortwave may cause it to interact with Irma as the storm moves into the Bahamas.
The concern here is that if this shortwave is stronger than some of the models suggest, than the upper level low will be able to form more quickly. If the upper level low forms faster in the Tennessee River Valley than expected, Irma will be forced to turn northward sooner over the Bahamas, and thus would become a threat for the Carolinas and possibly even Virginia. The possibility of Irma escaping out into the Atlantic Ocean with no landfall is still quite unlikely due to the position of the Bermuda high.
The location of this key polar shortwave is what I think is causing some of the model flip flop because that polar shortwave is in an area of poor sampling. Therefore the global model guidance used to forecast Irma’s track has a high degree of error, and also why there is so much volatility in the models from run to run. The shortwave is also why the threat of Irma tracking east of Florida to locations further north to North Carolina remains on the table today. However, as I highlighted in yesterday’s post, a track into the Florida Keys and up the west coast of Florida is still a possibility – it’s just not a favorite model solution today. As shown below, even the NHC official forecast for days four and five are seeing large adjustments, and these forecasts have errors of 175 and 225 statute miles, respectively.
Irma’s future intensity
While the models have a case of the flip-flops in terms of the forecasted track, what is remarkable is that there is very little disagreement on Irma’s future intensity. Since last Friday when I first started writing about Irma, it was well forecasted to become a major Category 4 or 5 hurricane impacting the northern Leeward Islands. These forecasts have been remarkably consistent in an era when forecasting intensity is typically the biggest challenge.
At this time it looks like Irma will track far enough away from the mountainous Hispaniola, which would have a significant impact on the circulation of the storm. Because of this and the warm sea surface temperatures along Irma’s track, the models have been forecasting a major hurricane to impact the southern Bahamas and south Florida for several days now and they are not backing away from this prediction. At this point it is a very safe bet, depending on track, that Irma will be a major hurricane (likely a Category 4 or stronger) near Florida by early Sunday morning. If Irma does not make landfall in Florida, the areas along the coasts of Georgia and the Carolinas should also be prepared for a major hurricane landfall.
New Analog Events and Insured Loss
I have been trying to find analog events for Irma, but there are very few events of this intensity that have tracked up the east coast of Florida. The events I provided yesterday would still fit in the model solutions today. However, David 1979 could be used as another possible Florida analog impact, but it was a weaker Category 2 hurricane as it tracked up Florida’s east coast. Due to the current intensity, any historical loss comparison can’t really be used at this time because Irma is expected to be a much stronger storm than anything I could find that has tracked up the east coast of Florida.
With the forecast uncertainty around the potential turn north, it is too early to provide detail on what potential losses could occur. However, just taking a glance at some of the disaster scenarios from catastrophe models, any hit at Category 4 or greater to southern Florida would be at least a $15 billion loss. Some of these scenarios only go up depending on the landfall location, such as a $100 billion loss or even greater, from a direct Miami hit. The ranges of potential losses are great. Matthew, however, showed us that if a storm can track just offshore, it can spare large levels of loss.
Special BMS Webinar Tomorrow
BMS Tropical Update – Hurricane IRMA GoToWebinar
Due to popular demand for today’s webinar on Hurricane IRMA (4p ET/3p CT), we have changed the weblink for the webinar.
Please use the link below to register for the Webinar.
Andy Siffert, VP/Meteorologist will be providing an update on Irma’s forecasted track and intensity.
Additionally, Julie Serakos, EVP and head of Cat Analytics will provide a modeling update and Kris Westall, COO and Urban Friesz, VP will provide an update on claims and accounting services.
Please join us for this important update.