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Sep 05

The Latest On Category 5 Hurricane Irma

Hurricane Irma continues its westward journey this evening as a formidable beast in the Atlantic. As of the 5 PM National Hurricane Center advisory, Irma is packing sustained winds of 185 mph, a “buzzsaw” by meteorological standards. Here is the latest forecast track for Irma. Note the slight shift north between Saturday and Sunday evening.

One thing to note is the environment the Irma ia heading into. Sea surface temperatures continue to sore into the 29-30 C range (mid 80s on the Fahrenheit scale) across the Caribbean and Bahamas with minimal wind shear. Incredibly, further intensification of Irma might not be out of the question. Heat potential is beyond ample for Irma to at least maintain its current intensity.

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Where is Irma headed? This is the trillion-dollar question. While there has been tremendous speculation based on ensemble and operational model outputs, the real answer is that no one knows for certain. A number of scenarios are on the table, but not one scenario has significant weight over the other. One of the most critical variables of Irma’s ultimate track is… you guessed it, the trough. If you got a dollar for every time I’ve mentioned the trough in the east over the last week, you could retire off that money, well… not really, but you get the just of the message being conveyed here. One thing I can say with pretty solid confidence is that we can almost certainly foil an out to sea track out of the picture. This being said, some type of US-impact is almost imminent, and I say almost because there is a very small window for the US to escape a direct impact, but it is possible.

WHAT TO WATCH FOR WITH IRMA: A number of things are on the playing field for where Irma is ultimately headed. Keep in mind, we are several days away from a potential US-impact. Here is what we are looking for:

  • We note that the westerly movement of Irma continues this evening. This is due to the ridge building to the northeast of Irma. Model output is suggesting this ridge will continue building to the west which would force Irma to continue its westward track until Irma has distanced itself far enough from this ridge that it can be its turn north. When that happens will depend when Irma is far enough away from this ridge and how it interacts with the trough in the eastern US. This point is critical and will be the difference between a direct hit to southern Florida or a “just miss”.
  • Thursday is a crucial day in the life and track of Irma. We need to keep close watch on Hispaniola’s interaction with Irma, or if there is any interaction. Hispaniola is a mountainous island nation, one that is notorious for shredding hurricanes to oblivion. However, if Irma remains far enough north of Hispaniola, hurricanes have been known to intensify in this region. This interaction will be critical for the life and track of Irma. Given how massive a system Irma is, I suspect that Hispaniola would have some impact on Irma pending interaction, but not certain how much of a demise Hispaniola would be for the system.
  • Days ago, we were hoping that Irma would move north of the 20N latitude mark. This evening, Irma remains south of this benchmark. Historically, hurricanes that remain south of this mark impact Florida in some manner.
  • Thursday will be the day that the nature and timing of the trough in the eastern US will be much more clear. This will determine whether the trough pulls Irma north sooner. In the event Irma misses the trough connection, we must acknowledge a greater chance for a Gulf storm. What part of the Gulf remains uncertain, in the event the trough connection is missed.

GUT FEELING: After scouring over the upper air pattern (500 mb), I’m suspecting that Irma might be a Florida storm. Not certain if Irma is a south Florida storm, Florida west coast storm or Florida east coast storm. It is tough making that type of call this early, but history and upper air patterns suggest that Florida is too close to for comfort with Irma. If I’m wrong, I’ll be the first to change my tone.

CALL TO ACTION: I’m still not comfortable giving the all clear for the Gulf of Mexico based on the missed trough connection potential. That said, folks from the Gulf to Florida and the Southeast US coast, please continue to take serious interest in this storm and have your hurricane ready plan set to go. It is much easier to not have to execute such a safety plan than having to scurry in hysteria at the last-minute preparing you and your family in the event Irma does make US impact.

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