One Last Irma Post

I promise.  It's just that the whole subject kind of has a built-in expiration date.  Denninger has a similar post with some similar data, so I thought I'd show some more. 

During the day Sunday as the storm was working its way north, I recalled watching the wind speeds reported back from NOAA buoys during Matthew and thought I'd watch Irma approach.  There's a webpage with a graphical front end,  that allows you to zoom in on an area, click on a buoy's location, and read the conditions its reporting.  Not every one reports everything, so you may have to experiment to find what you're looking for.  Here's the map you see when zoomed in around Florida.

You'll notice I have three of the yellow diamonds circled.  These are Key West, Vaca Key and Naples.  (Red diamonds are buoys that are offline).  If you'll recall, the storm crawled along the north coast of Cuba, then hung a right and went for the Keys.

By the time I remembered to look up this web site, it had already gone through and I didn't know where it went.  So I looked at both Key West and Vaca Key (on Marathon).  Neither of them had a wind measurement over 60 knots - 69 mph while the official winds were 150.  How could they miss it?  Were they both so far from the eyewall they missed the strong winds?  Now the distance from Key West to Vaca Key is about 50 miles, and Hurricanes 101 says the strongest winds exist only in eye wall, but it's still a puzzling result.  Did the hurricane thread the needle between them? Yes, it turns out it did, making landfall at Cudjoe Key, which is virtually the halfway point.  If the eye is 10 miles diameter (a wild-assed guess), that means about 20 miles from the innermost eyewall to either buoy.  I know the winds tend to drop off with distance, but that fast?

One of the reasons I thought to come to look at these buoys is that I noticed the same thing last year during the buildup to Matthew.  Official winds were in the neighborhood of 150 mph, but I never found a buoy that went above 100, even ones the storm had gone right over.  Unfortunately, I didn't write anything down. 

Still, I was puzzled.  So as the storm crept toward Naples, I picked that buoy to monitor.   Here's a screen capture.

I've highlighted in red the time, between 4:54 and 5:00 PM, that the eye went over the buoy.  The winds dropped to under 10 knots and the barometric pressure dropped to its minimum 27.75 inches.  But note the winds right before and right after the eye passage: 22 knots: 25mph.  Now look for the highest winds near those times.  The highest wind before the eye was 42.9 kts or 49.4 mph.  The strongest wind after the eye passed was 55.9 kts or 64.3 mph, an hour after the depth of the eye.  These are not a hurricane force winds, which start at 74 mph. Irma was not a hurricane when she hit Naples. 

I keep coming across little things that make it seem that they systematically overstate the winds.

For one example, on Saturday morning, one of the admins at Central Florida Hurricane posted that he was watching the wind speed coming in from the hurricane hunter aircraft, and they were showing the wind at 122 mph.  Minutes later, the Hurricane Center posted the official forecast and it said winds were 155. Why?  On the other hand, they dropped the winds to 125 on the next update, so maybe it was just too late for them to incorporate the new data.

For another example, I found this interesting comment on Watts Up With That by a guy calling himself FLengineer (no relation).  There's a lot of detail here on NOAA changing the way they report winds.   The quote is actually too long to post here, but let me grab a little bit of it:

After digging into the specs and extracting the measurements from the transmitted data it looks like the advisory intensity is purely based on a peak wind speed measurement over a 10 second interval at flight level between 2200-3000 m altitude. I found a decent paper on the measurement equipment aboard the aircraft from 2007 (http://www.aoml.noaa.gov/hrd/Uhlhorn/MWR2007Uhlhorn.pdf) and thought some of their conclusions were interesting.

Prior to 2005 intensity was determined by a model that took the flight level winds and extrapolated 10m surface winds from those. In 2005 the planes were outfitted with an updated SFMR radar that measures the ocean surface emissivity which is correlated to surface wind speeds. Due to lots of tropical activity in 2005 the new radar was able to help derive a better physical model matching the readings with dropsonde data.

In their conclusions the earlier quadratic models consistently underestimated winds at speeds > 50 m/s (111 mph). They also found that earlier boundary layer models were underestimating winds in the eyewall by as much as 10% when compared to dropsonde readings.

So are the storms more intense because of increased SST or because of better models, higher frequency sampling, changes to peak measurements from 1 minute averages, and improvements in the sensor equipment?
...
If we look at the most recent Air Force data in Irma the peak flight level wind was 133 kts (153 mph) SFMR surface wind was 120 kts (138 mph) and same 88% linear adjustment would extrapolate 134 mph. NHC 11 pm advisory for Irma is 160 mph.

What does it all mean?  Beats the heck out of me!  Here we have several lines of data showing that when winds are measured in the monster hurricane, it's not what's being described. 

I know that measuring and quantifying these things isn't easy, but there seems to be a systematic tendency of the NHC to over hype every hurricane.  The NHC itself has not been friendly to the "global warming causes hurricanes" crowd, and one of the NHC's chief scientists, Dr. Chris Landsea, withdrew from the IPCC reports over their reports not being backed by science.  Maybe they're just covering their uncertainty about what to forecast by getting everyone in the state to leave.  We know the Weather Channel and virtually all of the news channels make their ratings and their advertising money on storms.  I know that I've seen TV weather folks whom I respect who will tell you to your face that "we have to make it as dramatic as possible to get people to leave".  But what if they don't have to leave?  What if leaving put them in more danger from other things.  How many stories did you hear of people who evacuated south Florida to the west coast and ended up going right into the worst possible place? 

I've seen this described as the biggest mass evacuation in history. 

Evacuating costs real money.  Did they negatively impact someone's life by having them take on the burden of running from the storm?  You've got to know that a lot of people can't really afford to drop whatever motels were asking for a few nights, and even more for meals.  What if they came home to a looted home? 

Let me leave you with a fun fact.  After looking around at various buoys from the keys up through Ft. Myers, and looking at some reports off that NOAA bouy page, I found one buoy with hurricane force winds: Fowey Rocks buoy, off the coast of Miami, pretty much 115 miles from both Cudjoe Key and Naples.