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.
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 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.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.
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.
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.
I wondered the same thing. On the Wunderground site, you can find a similar map with data from personal weather stations. The high winds tended to be spotty, and I did see a report from a PWS half a mile from me that reported a 103 mph wind gust. I am thinking about getting a PWS myself. They only cost $150 or so.ReplyDelete
I've thought about it, too. It would have entertainment value, too.Delete
Pedantic mode: gusts don't count. Hurricanes are defined by 1 minute straight winds. Although that WUWT comment by FLengineer makes it seem like they might have changed that.
Judging by our neighborhood, I'd say we had hurricane gusts and maybe even Cat1 winds. I have no data to back that, just comparing what I see to the '04 storms.
You had me at "models". More and more often, I'm seeing results of computer modeling presented as FACT, even when it contradicts the base reality of actually putting your eyes on the issue. (I had no idea that the values for windspeed they were reporting were 'adjusted' or modeled. )ReplyDelete
We had the Army Corps of Eng here in Houston talking non-stop about their flooding models and how there wouldn't be any new flooding from their dam releases, WHILE THE NEWS WAS SHOWING FLOODING.
Like the old joke about weathermen, it was clear they weren't even looking out the window.
Models can be useful as a guide, but they have no historical value when they are changed, especially if the fudge factors are changed.
All too often, we are seeing that data has been extrapolated, normalized, adjusted, or just made up from the whole cloth. This seems to be especially true in the weather and climate areas.
One reason for hope is the proliferation of home weather stations, aggregating sites like weatherunderground, and wider exposure of the datasets. Wide exposure shows just how much 'making it up' goes on. Increased granularity shows the ground truth and involves more people and shines a bit more light on the whole process.
Focusing in on the relationship between the media's ratings and revenue.ReplyDelete
Philadelphia residents will point to the overblown forecast of "the storm of the century" in 2001 by a local forecaster. The forecast was so completely wrong that it is still used to describe something that was predicated totally and absolutely wrong.
The larger problem is that when the little boy cries wolf for every storm, then the weather folks will be ignored even when evacuation is the right answer.
The larger problem is that when the little boy cries wolf for every storm, then the weather folks will be ignored even when evacuation is the right answer.Delete
Bingo! That's the problem. People will start saying, "oh, the hurricane center always exaggerates" or "the last time they said it was a horrible storm, we were fine so I'm not evacuating".
Imagine having evacuated out of Miami and after hours of nothing but hassles, you get off the interstate and take back roads over to a small town on the west coast. Next thing you know, you're in worst possible place for the storm. Are you going to take that advice again?
The NHC will always say, "don't look at the centerline - it can go anywhere in the cone" but the forecast is so inaccurate that the cone covered the entire state. For a few hours on Saturday night or Sunday, our chances of hurricane winds went to zero. By Sunday afternoon, they went back up into the 30% range.
Maybe it's just the nature of the path the storm took and Florida's odd geography, but to get out of the state from Miami is about a 6 hour drive on a good day. You have to get out of town a day or two before the storm when they really have only the foggiest idea of where it's going to hit or how bad it's going to be. I think that they ordinarily say the error bar is 100 miles wide at 24 hours, and add another 100 miles wide every day. Peninsula Florida is only 120 miles wide at the widest - I've ridden it on my bicycle in a day. A 200 mile wide error on the cone covers the entire state. Now where do you go?
Ah, but the tower cranes on the buildings in Miami were required by law to be designed and installed to withstand 200 mph winds. However, at least two of them collapsed. Now since they had been designed by certified engineers, and since they had been inspected by government officials, that clearly means there must have been winds greater than 200 mph over downtown Miami!Delete
I saw a TV reporter in Miami, probably Saturday night. He was pointing out the multi-story condos in the background and saying "the winds get exponentially stronger with height!!".Delete
No. No they don't.
I couldn't take it and swore off just about all TV for the rest of the storm.
Winds DO get stronger with height, but nowhere near exponentially.Delete
Having said that, I question the relevance of wind measurements taken from 2000+ m altitude to conditions on the ground. I hadn't thought of that being a way that the storm could be made to look worse compared to past storms where wind speeds were measured closer to the ground.
It was that key word, exponentially, that made me crazy.Delete
I understand the problems with measuring wind at the surface when flying over an ocean with perhaps 50 foot waves. How is surface defined? So they need to choose some level to standardize on, and I suppose 10 meters is as good as anything. 10 meters is above the top of my house, and above my neighborhood, but certainly not above those condos the reporter was talking about.
Note that the anemometer on Fowey light is at 43.9 meters above sea level.ReplyDelete
Also, they tell you to evacuate but then won't let you back in to inspect / protect your property. Government knows best. :(
Also, they tell you to evacuate but then won't let you back in to inspect / protect your property. Government knows best. :(Delete
Probably the biggest reason I can't stand the thought. But that tells me, "I'm too attached to my stuff". As someone said.
Interesting graphic, so thanks.Delete
I'm aware of winds going up with elevation, and I'm pretty sure the NHC uses 10 meters as the height for the standard winds and their declarations of storm category, and I assume that's why that graphic went to 33'.
I always thought that was due to some drag and turbulence from the ground and the winds didn't change as rapidly in the second 33 feet as the first.
I guess the question about buoys comes down to how they work. Do they compensate for the buoy's height? If not, everyone who may be looking at the data has to do it manually.
If I remember my wind industry days right, many turbines are 50+ M high since the curve of increasing wind speeds usually flattens out above that height.Delete
There are exceptions, of course, and one reason Tehachapi pass in California (spelling?) is so popular for wind farms is that it has high speed winds close to the ground so it is easier and cheaper to set them up there. Those winds are also heavily used by birds and those same turbines appear to have a higher rate of bird fatalities than elsewhere. As you know, every decision involves trade offs.
I'm on the space coast about a mile inland. All I know is that I had trees come down which stood through MathewReplyDelete
Last year. I have a home weather station with the anemometer mounted on a six foot pole above the peak of my roof. It registered a 94 mph gust at one point. Likely one of those tornadoes came close ?
That and it blew the leaves off almost every bush and tree that still stand. This with the eye wall supposedly a hundred miles away ?
I'm in a similar situation, about half a mile from the Indian River so about two from the Atlantic. We also had quite a bit more wind than Matthew, and I think we had real hurricane force winds. My wife and I are both noticing that most of the trees and bushes we can see have their leaves turning brown and falling off. Just about everything in our yard has had that happen. Right now, it looks like the worst leaf accumulation we get in the fall - usually late November/early December. Someplace was saying it's a trauma reaction. The leaves may come back - in time to fall off in late November/early December.Delete
Irma was very big, and for quite a while, we were in the worst quadrant of the storm - the NE quadrant. Winds were coming onshore after long stretches over water and I think they got stronger because of that.
If you go to the Melbourne NWS office, they list max recorded winds and gusts around East Central Florida. These are two minute values and there's a lot that are well over hurricane force. Cape Canaveral AFS recorded 110 kts, or 127 mph. They also include some non-airport measurements that are eye-popping. Vero Beach city hall recorded a mind boggling 140 kts, or 161 mph. It's the kind of number that makes you wonder if their measurement is valid, but the NWS is using it.