7 September 2017

This Looks Bad- Very Bad.

Posted by Dan Satterfield

Irma in all 16 channels of GOES 16. From Bill Line and his GOES Blog.

My hopes that Irma would turn just east of Florida are diminishing tonight. If the eye stayed just offshore the damage would be FAR less than a landfall. Remember that those 170 mph winds are concentrated right around the eye, and if that eyewall stayed offshore the winds would not likely go above hurricane force except in gusts along the coast.

The worst scenario I can imagine is a Cat 4 or 5 going right up along US 1, and the later runs of the Euro model are forecasting something close to this. This model has beaten the pants off the NOAA GFS model and is even superior tot he NOAA hurricane models. It has also been by far the most consistent and today’s runs are edging it a bit west of Miami around landfall.

Most of those spaghetti plots you see on TV are from the GFS or other hurricane models since the Euro data is copyrighted and while some of the data is shared, you have to pay to get the good stuff. The NHC and many private meteorologists are getting it (myself included) and relying on it as the best guidance. A good thing to remember though is that ALL model forecasts are wrong, but they often give very good information.



Irma, just before sunset Thursday. Geocolor image from U Wisc.

Some tips for those who have never been in a hurricane or think they have and have not.

  1. Unless you were in the eyewall, you were not in a real hurricane.
  2. The winds will be markedly less inland just a few miles due to friction.
  3. The highest winds will be recorded right in the eyewall and if it makes landfall the winds near the eye will go above hurricane force well inland.
  4. The storm surge will be highest if the eyewall is just inland from the coast and high tide Sunday in Miami is around Noon and it is a rather high one at 3 feet above sea level. This will add extra water on top of the storm surge and the waves.
  5. We will not see the kind of rain totals with Irma we saw with Harvey since it will keep moving.