Hurricane Irma: September 9, Update D

One more quick update on Hurricane Irma, and then it’s sleepy time! I’m going to leave Hurricane Jose out of this one, even though he is a cat 4 storm with winds of 130mph, because he is passing north of Puerto Rico as he moves away from the islands of the Caribbean and isn’t being too much of a bother.

Hurricane Irma is now officially a very weak cat 4 storm, with winds of 130mph (cat 4 range: 130-156mph), central pressure 931mb:

Hmm. I am not totally convinced about this upgrade in intensity to a cat 4 storm, when an hour ago she was a mid-sized cat 3 with winds of 120mph. Plus, the NOAA data on the ground does not support what they are saying. From a plane, the NHC said that the data shows that

“maximum sustained winds have increased to near 130 mph (210 km/h)”

Meaning that the winds are not 130mph so strictly speaking, she is still a cat 3 storm! They also say that:

“Hurricane-force winds extend outward up to 70 miles (110 km) from

the center, and tropical-storm-force winds extend outward up to 205

miles (335 km).”

And that she is currently:

“ABOUT 70 MI...115 KM SSE OF KEY WEST FLORIDA”

This increase in intensity and the wind spread doesn’t match the NOAA data anywhere on the ground in the Keys at the moment, which are all reading winds of around 40-50 mph – i.e. at Tropical Storm level (see below for the data). Instead, for proof of the hurricane wind speeds in the Keys, the NHC offered this…

“A private anemometer at Marathon Key, Florida, recently reported a wind gust 

of 88 mph (141 km/h).”

<Minor Rant Alert!> This seems a little like picking the data to make the point. Grrr. First, they are ignoring multiple NOAA sensors in favour of a single private sensor which had a measurement of a gust that shows a high wind speed, and it looks like they used that makes their case. And second, the wind speed of a hurricane is assessed based on sustained winds, not a single gust, which could be a quick whisk in a thunderstorm. The 1am update was more logical and consistent – I think the 2am is an overestimate. Grrr. < End Minor Rant Alert!>

This doesn't mean that the wind speed in the Key's won't increase - in fact it definitely will get to hurricane strength! But at this point, 70 miles away, there are no hurricane force winds being recorded, even by NOAA's National Weather Services's own sensors - only Tropical Storm force winds. 

It actually also doesn't mean that she won't be a cat 4 by the time she gets to the Keys (she still has half the Straits to cross after all), but if she isn't there yet, then don't say it. 

Moving on to the track (and here the NHC do excel)... it looks like she has made the turn finally, and is now heading NW and towards the Keys. Officially she is at 23.8N, 81.3W, heading NW at 6mph:

As she moves away, even though Cuba is still under some tough convective activity, the wind shear, which you can see in the satellite image below, is really helping to spread some of that activity over Florida, parts of Georgia, and up the east coast:

Here’s the latest from the Key West Radar:

From Key West Airport, at almost 2am (1:53am) the wind speed is still around 40mph at the airport – so just about Tropical Storm force:

The highest wind speed recorded at the moment is still at Vaca Key (from the Tides Online site) where the winds are approaching 45 knots = 51 mph and the water level is still almost 1.5 ft above normal. At this point in time, the Keys are, essentially, in under a Tropical Storm (TS range: 39-73mph).

As I mentioned earlier today (I think it was today), if you are on the west coast (not including the Keys) and she is to the south of you, the water levels will actually drop because she is pushing water away… if she is north of you, they will rise. A lot of the west coast of Florida is currently at around 1ft below normal. Naples, the closest to the storm on that coast, is just over 2 ft below normal (the green line in the upper figure):

That’s it for today. More tomorrow.

Thinking of you all… stay safe!

J.  

--> Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm
-------------------------------
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.