Guest Post by Willis Eschenbach
When is a hurricane not a hurricane? Well, when it doesn’t blow 64 knots (33 m/sec, 74 mph), because then it’s only a tropical storm. Inspired by a post over at the Cliff Mass Weather Blog, I’ve been trying to find a single report of sustained hurricane force winds anywhere along Irene’s path at or near landfall … no joy. I knew exaggeration was the order of the day for some folks in the climate debate, but I hadn’t realized that the illness had infected the Weather Service itself.
Figure 1. The path of Tropical Storm Irene over the mainland of the US. Symbols with a yellow center to the black storm symbol indicate a (claimed) hurricane. SOURCE ibiseye
We were fortunate in that we have very good records of the wind speed when Irene made landfall. It went almost directly over the wind recording station at Cape Lookout, at the bottom of Figure 2.
Figure 2. A closeup of Irene’s landfall. There are four wind recording stations in the area, at Beaufort (below the “70” marker at lower left), at Cape Lookout (bottom left) and at Cape Hatteras (upper right). The Onslow Buoy is located offshore, southwest of Cape Lookout.
The wind record at Cape Lookout is quite interesting, as the eye of the hurricane passed right over the anemometer there. Figure 3 shows the wind dropping as the eye went over, coincident with the deep plunge of the barometric pressure to 950 hPa.
Figure 3. TS Irene wind (light blue) and barometric pressure (violet) at Cape Lookout before, during, and after landfall. Green line at the top shows the minimum wind speed for a storm to be classified as a hurricane (64 knots).
Figure 3 shows the classic pattern of a hurricane passing directly overhead. The “eye” of the hurricane has almost no wind, and is at the center of the low pressure area. You can also see the “calm before the storm. But what you can’t see is any trace of hurricane force winds.
Not finding hurricane force winds at the eye, I looked at the other nearby stations as well. The weather station at Cape Hatteras is in the “dangerous semicircle”, the right hand side of the storm track (Fig. 2) where the speed of the storm is added to the speed of the winds circulating around the eye. Beaufort, on the other hand, is in the safer half of the storm, where the speed of the storm is subtracted from the circulating speed of the winds. The Onslow Buoy is also in the safer semicircle, on the left of the storm track in Figure 2. Figure 4 shows those records.
Figure 4. Winds at TS Irene landfall for Cape Lookout, Beaufort, Onslow Offshore Buoy, and Cape Hatteras.
As you can see, although Irene definitely qualifies as a solid tropical storm (winds greater than 35 knots), it does not reach or even really approach the 64-knot threshold for hurricanes. Other than at the eye itself, the winds did not exceed 50 knots, much less reach 64 knots.
After crossing over the land near Cape Hatteras, Irene headed back out to sea again. I thought perhaps it might have picked up steam when it went out over the ocean again. It made a second landfall in Atlantic City and went along the coast to New York.
Figure 5. Second landfall for Irene.The nearest stations to Irene’s track are Costeau (near Mystic Island above Atlantic City), NY Harbor Buoy (outside the mouth of the harbor, in the dangerous semicircle), Sandy Hook (hook shaped peninsula just above Long Branch and central hurricane symbol) and Kings Point (near New Rochelle above New York City). Note that the storm is claimed to be a hurricane until it gets well into New York State.
It appears from an examination of the station data shown below in Figure 6 that it did not pick up strength over the water. By the time Irene reached land a second time, it barely qualified as a tropical storm, much less a hurricane.
Figure 6. Wind speed from Tropical Storm Irene as it made the second landfall.
So, despite looking at Irene before, during, and after both landfalls, there is no hint of a hurricane anywhere. By the time it got to New York the eye of the storm had dissipated, what was left were huge bands of rain clouds.
Is there a moral in this story? Well, I can understand people taking extra precautions, better safe than sorry is a good rule. And I certainly imagine that when the Weather Service re-examines the records, the error will be corrected.
But that doesn’t help in making the decisions. As soon as Irene hit land, it should have been downgraded immediately to a tropical storm. That’s what it was, not a hurricane making landfall but a tropical storm. As far as I can tell, we still haven’t had a hurricane make landfall during Obama’s presidency, a historical oddity.
Individuals and city mayors and the people in charge of the emergency response can call for any level of reaction to storm threats. They may decide an exaggerated response is appropriate.
But they need accurate information to do that, not exaggerated claims. They need the actual facts, the best estimates with no exaggeration on either the high or low side.
In this case, it appears that people got so wrapped up in the question of the winds, and the fear of the winds, that they overlooked what actually made Irene unusual. This was not the wind speed, but the size of the storm. Combined with Irene’s generally slow movement over the ground, Irene’s huge dimensions meant that any given area would get rained on for a really, really long time.
And in turn that meant that the cities and towns along the coast, the ones receiving all of the attention from the fear of high winds and attendant storm surges, weren’t the towns in danger. Unlike the coastal cities, the vast expanses inland were not able to have the rainwater just flow back into the ocean. Inland, the water piled up and overflowed the banks.
And so, because of the overestimation of the wind speeds, our attention was diverted from the real threat. Because of the claimed hurricane-force winds, a storm surge up to eight feet was predicted in New York Harbor. But in the event, the storm surge was barely three feet, a non-event … and meanwhile, New England was getting badly flooded.
So the moral to me is, honesty is the best policy for a National Weather Service. Don’t exaggerate the possible effects to be on the “safe side”, don’t minimize the possible effects. Just give us the best information you have, and let us make up our own minds. As Sergeant Friday used to say … “Just the facts, ma’am” …
w.
NOTE: All wind data is from the NOAA National Buoy Data Center http://www.ndbc.noaa.gov/.
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Just to play devil’s advocate, aren’t there a myriad of factors that go into determining if a storm is a “Hurricane of Category [x]” or just simply a “Tropical Storm”?
-If so could you elaborate on how many of those criteria a storm has to meet or exceed?
-Is it possible it met enough criteria elsewhere?
And finally, there was talk that meteorologist were pushing for certain metrics based on barometric pressure to be added to the list of factors, was this “creative labeling” maybe a bit of inside politics on their part to push for a change in the assessment of these storms?
Any constructive replies appreciated.
“Just the facts, Ma’am. Nothing but the facts.”
Excellent post, Willis. Our federal weather guys have a lot of explaining to do,
Fellow I know who rode out the “hurricane” on the Jersey shore in his condo 100 yds from the water says he has been fishing in more windy conditions.
Thank you! As I posted before Irene hit landfall, it would move east and be insignificant. However, it did quite a bit of damage and produced flooding from heavy rain.
Maybe if a forecast is understated, they risk losing their job. Better for job security to over state a certain degree of possibility than to sleep under a bridge after the blame game ends.. 🙂
In the US, aren’t former presidents formally addressed as Mr President? Maybe it’s just a case of once an hurricane always an hurricane .
The thing is, the media was all set up along the coast for a big surge, etc. You could practically see Anderson Cooper drooling over a Katrina repeat. In order for them to cover the rain/ flooding they had to move inland and follow the track. Whole lotta hassle, and money to do that, and far less dramatic watching the creek rise. The NWS was just catering to the newsies.
If Al Gore and Bill Nye the Anti-Science guy are claiming that global warming causes more quantity and severity of Hurricanes, then doesn’t that same logic prove that global warming must have ended the past 3 years?
I was discussing this on another forum, and have some suspicions about what happened. First, the semantics. To be classified as a hurricane, a tropical cyclone must have maximum sustained winds of at least 74 mph. A couple of things about that. Note that it doesn’t specify surface winds. Secondly, the only way to find the maximum wind is to traverse the hurricane at altitude with an aircraft, which is what NOAA does to find the maximum, which may not fall over a surface weather station or weather buoy.
It’s my suspicion that NOAA takes these winds aloft readings and converts them to “surface winds” by some algorithm. If that’s the case, there algorithm may be busted, or the maximum winds never passed over a weather station.
Since hundreds of millions of dollars (at least) were spent preparing for Hurricane Meh, I think NOAA owes the world an explanation.
Did you account for wind speed average times which may be different for different locations? Also, did you account for meter height at each location. I’m not disagreeing with the general idea of the story only wanting to make sure the data is being correctly reported before comparing different station locations.
In 1972, I was living in Western Pennsylvania. Look up Hurricane Agnes on Wiki some time; that did the vast majority of its damage as a TS. My two vivid memories are pictures of the governor’s mansion in Harrisburg flooded to the second story, and my mother (the MN tornado veteran) herding us into the basement.
Which is not to suggest that scientists and the media shouldn’t be getting it right in their reporting on the details, because of course they should.
Gasp, I cant believe I would ever disagree with Willis. But just here me out.
The damage done indicates this was a hurricane. You dont blow down that many trees on Long Island and have wind gusts to 91 mph at Sayville at 10 feet without hurricane conditions.
By this logic, Houston did not have a hurricane with Ike as there were no sustained hurricane force winds anywhere within the city. Intercontinental gusted to 81 with a sustained of 56.
Here look for yourself, the obs all through the city of Houston. All the glass, all the damage, etc should have been downgraded, right?
http://www.srh.noaa.gov/hgx/?n=projects_ike08_pshhgx
I have been through 4 eastern hurricanes. They are not as they are in the tropics. The winds come in fits and spurts and often the damaging winds come and go quickly not in a building crescendo, but in on and off fashion, multiple times and even while the storm is pulling away. This is because the turbulent transfer needed to bring the strong winds down to the surface is only left in bands as the storm weakens and the air cools around it. Still the flow on the eastern side of the storm aligned will do this, and behind the storm ( the sinking in the drier air often brings roaring west wind). On the northwestern side, the cooling from the trough picking up the storm is like a giant seeding experiment, spreading the rain out and forcing the condensation process to be rapid away from the center, spreading the energy out.. So you have to understand, its very different from the classroom donut of perfect wind everyone wishes to see. . I agree this is not the kind of hurricane you see in the tropics, but that kind of damage to the NC outer banks and the kind of major tree damage and storm surge to southern New England and Long Island is not caused by a tropical storm. There was more tree damage in Rhode Island than in Bob which hit as a cat two and blew away the anemometer at block island at gusts over 120 mph
It is a reason for why the power scale I have gives a more accurate description of what the storm will do.
think of it this way. Suppose you had an Anthony Watts tested anemometer every 25 feet on the beach from Montauk to JFK, 10 meters high , or across all of Long Island. Do you really believe, given the damage, which in some cases was worse than GLoria , you would not have found hurricane winds.
heres what we can agree on.. if it was a tropical storm, it had the lowest pressure and did the most damage from wind that we have ever seen from a tropical storm on the east coast, since it did more tree damage than other hurricanes that we are NOT arguing about. 7 million people without power, 20-30% of trees damaged.. a 951 mb tropical storm, unloading a foot of rain,blowing down trees killing dozens and causing 7-15 billion dollars of damage.
Sadly, this whole argument is probably finding its root with the maliciousness of the AGW crowd that wants to pump weather events up to emphasize global warming. And I understand our need to fight back. But against the backdrop of history, and previous storms and damage patterns, I think Irene belongs as a hurricane. And let not your heart be troubled, for history and facts are on our side in that fight, whether we wish to argue about this. I only ask that you ask yourself, well how did that house get pushed over and why were so many trees knocked down with this, but not with others. It cant all be because of the rain.
Keep up the good fight. and please dont take this as anything else than what it is, bringing up other ideas to go along with the observations presented here.
cheers
Are the graphs of hourly wind speed? There look to be about 24 data points per day.
Being from the west coast, I have heard people say the east coast blows, it’s good to know it doesn’t blow as hard there as some people say.
Pointing out that Irene was actually a Tropical Storm — not a Hurricane — at landfall is like pointing out that the Recession ended in July of 2009. Could be technically correct, but the impact doesn’t feel like the it.
The over exaggeration of all things weather or climate related has long been the standard for the media and has now become the same for government “science” organizations.
I am sure there is way back from this precipice we have created, but I am sure we will get there soon. It seems every one who brings up the subject is shouted down with the precautionary principle argument.
I think the push-back (against the great Hurricane Irene) is warranted and nice work Willis. Joe Bastardi makes an important point (wind speed alone doesn’t define a hurricane) but when the American President is on standby for a tropical storm (and nowhere to be seen on the economy) it makes me wonder if someone is waiting for a weather miracle (i.e. here we are to save the day, and oh by the way we told you so). If Irene turned into a Cat 3 they would be looking pretty good. Oh well, on to the next disaster in waiting..
Thank you sir.
I tried to follow this storm very closely as I have family in the Wilmington, NC area approx 5 miles from the beach. The NHC maps were so large scale that it was impossible to get any decent idea where the eye was. I had to use local weather forecasts (Accuweather, Wunderground, Intellicast, etc.) to try to follow what was happening. Using the local radar images, possibly originating from the Nat Weather Service, I would locate the center of circulation as best as possible and then check the local forcast but there were no major wind issues. I was baffled. The NHC was reporting hurricane force wind extending out +- 60 miles but I could not find anything close to it. I followed it up through Virginia and the same results. Took a break and Sunday morning (4:00 a.m.) began following it again. NWS radar was not available so I used the same technique using local weather reports and using the animate features I was able to determine that Irene was making landfall in NY about daylight. Local report at about that time at the big airport just to the east of NYC was reporting about 35+- mph and gusts to upper 40’s if I remember correctly. At that point I was confirming to those within my circles that I was certain someone was playing political games on a big scale.
Through my observations of estimated rain storm totals derived from radar, I could see that 30-50 miles east of the center of the so-called hurricane, they were in the 10-12″ rain estimates. TV was still concentrating on wind, but that was not the real issue with this storm.
There is a lot of lost credibility with regards to this storm. Does the public now need to take a boat offshore to determine what the reported status of a storm is? Do we trust the NHC? If the next one is the ‘real thing’, will anyone listen? Time will tell, but this one will be hard to sweep under the carpet. If this is defended as actions of the ‘Nanny State’ for our own good, then I want a new Nanny.
Irene was not a hurricane on landfall-the facts undeniably speak for themselves-in terms of damage done, we have to remember that the East coast has not seen a tropical system of this strength in quite some time-its been since Gloria that Long Island has seen winds even near 60mph-thats a span of over 25 years-so there were likely many trees that had not even seen those kinds of winds-that combined with the wet ground would account for the seemingly worse damage. Before Gloria-which did contain much higher winds-there was Belle in 1976, and Doria in 1971 along with Donna in 1960. I am referring to this winds with the trees fully in leaf-there have been many noreasters with winds as strong-but with no leaves on the trees its a whole different ballgame.
In reply to Joe B;
It seems that the destruction your are describing can be attributed to the long duration of the high winds associated with the size of Irene as much as potentially higher localized winds. Would it not be better for future warnings to say “hey, look what a large tropical storm could do – you better leave for the next “true” hurricane”.
Anyone who says Irene was not a hurricane has not lived through both tropical storms and hurricanes. I can tell you from experience that this was a hurricane. Barely a hurricane, but one nonetheless. The wind speed near the surface can be different than the wind speed higher up.
This business of calling former presidents as “Mr. President” is relatively new. They used to be “Mr. Hoover” or “former president Eisenhower” to signify they were once again ordinary citizens.
I could be wrong, but in my memory it is only in the post-Kennedy era, that the job descriptor senator became the title “Senator” and ex- presidents became “President” for life.
I personally think it is sign of the trend in America to create a permanent elite class like the European nobility. Some perhaps see this as a way to keep the common rabble down. After all they know what is best.
I was screaming exactly that at my television all day from here in Alberta, Canada – and turned to CNN and Holy Mother of Jesus Armageddon had struck the fatal blow to the US east coast. The CNN anchors and reporters were hysterical – running around looking for hurricane wind, and other assorted hurricane events. Was New York washed away or was it just CNN or is New York now missing under the flood?
From satellite presentation, and from the location of wind reports, might Irene have been a subtropical storm of hurricane strength at landfall? Having been picked up by the trough, the cloud pattern resembled part tropical system, part extratropical frontal system. The winds presented here aren’t of hurricane strength, but a subtropical system doesn’t necessarily have its strongest winds in the centre/’eye’, and would be far from symmetrical, as was the case with Irene according to NHC.*
NHC’s discussion comments regarding Irene having a much lower-than-normal ratio of surface winds to flight-level winds is also perhaps more indicative of a non-tropical or subtropical system, where 950mb would be expected to produce some hurricane-force winds somewhere but not necessarily across a broad area and not high up the Saffir-Simpson scale.
Wind damage to structures will be good evidence of wind strength, but I’d be more cautious when looking at fallen trees in New England. Irene hit after previous rains had already made the ground softer and trees were in full leaf, so trees that may have stood up to a nor’easter in November would’ve been uprooted by Irene.
Depending on where it goes (and it could be Louisiana, Mexico or Sydney Harbour at this rate), I suspect Lee will render the No Hurricanes Under Obama tag obsolete anyway.
*On a cautionary note, look at the NHC report on Katrina and you won’t find any reported sustained winds that get close to Cat 3. Wind sampling can be very hit-and-miss, even by the Hurricane Hunters.
As weak as this one was, it still managed to take out a section of Hatteras Island. Also, if memory serves, it appears to have tracked almost right over the sample site for the recently discussed paleo study that looked at sediments.
Thanks for this post, by the way.
Doug in Seattle says:
September 1, 2011 at 11:11 am
The over exaggeration of all things weather or climate related has long been the standard for the media and has now become the same for government “science” organizations.
I am sure there is way back from this precipice we have created, but I am sure we will get there soon. It seems every one who brings up the subject is shouted down with the precautionary principle argument
—————————————————————————–
Agree totally. This Irene business – whatever the precise facts may be – is another example of media-overhype. Lies, basically. The media lie to us all the time and not just about this.
Put it this way: if you knew somebody had definitely lied to you about one thing, would you trust them on another?
Don’t be so sure about being allowed to back away from the precipice anytime soon though… And we didn’t create it, they did