Sunday, September 10, 2017

Hurricane Irma: September 10, Update A

I just got the news from St. Thomas via the relay pigeons that Tom and Sheri J. are ok and the house is ok! Hurray! 

Officially Hurricane Irma has been a cat 4 storm with winds of 130mph over the past few hours, based on plane measurements and estimated speeds at the surface, although from the satellite imagery she has been fluctuating, including almost losing her eye at one point:
I would say she is a cat 3 (and maybe even a cat 2 as the eye is really poorly formed), given the appearance and the actual data on the ground. At 130mph, she is on that cat 3/4 border (cat 4 range: 130-156mph) so I'll go with the NHC and we can argue about it later! ;-). Central pressure is 929mb. She made landfall over the Cudjoe Key, about 29 miles from Key West (where sustained winds reached a max of around 70 mph – see below) and about 10 miles from Big Pine Key (where there was a max gust of 106mph – if anyone refers to gusts (which are instantaneous), it means the sustained were weaker), at 9.10am EDT today - all suggesting a cat 2 or 3. She is now in Florida Bay, as you can see from the radar:

She is currently officially at 24.8N, 81.5W heading NNW at 8mph, although the satellite image suggests she’s a wee bit north of that at 24.9-25N and 81.5W, which suggests that she is currently moving due north (the previous advisory had her at 24.5N, 81.5W). And if that is the case, then she is on the eastern edge of the cone:
Which means she may make landfall around or south of Naples (or maybe Ft. Myers) and move inland from there. A southern landfall is the best-case scenario for the rest of west Florida (e.g. Tampa Bay, Sarasota Bay), because the waters will generally be pushed away from the coast (except for those who live on the west side of the Bay, where the waters of the Bay will be pushed against you. Also, an earlier landfall along with the wind shear will reduce her intensity faster.

Looking at the Tides Online site, the storm surge at Key West is now rising as she has gone past, and is at 3ft above normal (to understand these graphs, see the Technical Alert! in this entry):

Whereas at Naples, it is currently 3ft below normal, the winds are increasing, and the pressure is still dropping:

I’m watching… just like everyone. I’ll be back later.
Stay safe!

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DISCLAIMER: These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know. 


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