Purdue study uncovers why some hurricanes balloon in size and what that means for forecasting future storms – well… maybe. It seems to simplistic to me as there are many other factors in hurricane formation and life-cycles. But….there’s this: “The study found that hurricane size growth rates do not change much with global mean warming, though global temperatures continue to rise.” -Anthony
When people hear about hurricanes, they often focus on the category rating: Category 1 through 5, based on maximum wind speeds. But not all hurricanes with the same wind speeds are alike. Some are compact storms while others can span the size of entire states. Larger hurricanes bring far greater damage, generating wider footprints of high winds, heavier rainfall and more dangerous storm surge.
A new study led by Purdue University researchers has uncovered why some hurricanes grow significantly larger than others and why this growth occurs rapidly under certain ocean conditions. The research shows, for the first time, that hurricanes grow in size much faster when traveling over locally warm waters where the ocean surface is significantly warmer than the rest of the tropical oceans.
“This discovery can be put directly into use for daily forecasting of hurricane size and impacts,” said Danyang Wang, postdoctoral researcher in Purdue’s Department of Earth, Atmospheric, and Planetary Sciences (EAPS). “It can also be used to better model hurricane size in long-term risk models used by industry to evaluate property risks.”
The discovery, led by Wang with guidance from professor Dan Chavas of Purdue’s EAPS department, was published in the Proceedings of the National Academy of Sciences (PNAS).
Wang developed the underlying theory, extracted and analyzed data from historical records and climate simulations, and wrote the manuscript. Chavas provided high-level feedback on how to connect the theory to real-world storms.
They were joined by collaborator Ben Schenkel, a research scientist at the Cooperative Institute for Severe and High-Impact Weather Research and Operations at the University of Oklahoma. Schenkel provided a tropical cyclone size database used in the analysis and helped clarify results across multiple datasets.
Before this work, scientists knew that some hurricanes expanded significantly during their lifetimes while others stayed compact. But the factors behind that difference were not well understood. Wang and Chavas showed that the rapid growth of storms is tied to “hot spots” in the ocean. These are localized areas where the water is significantly warmer than the surrounding tropical waters.
The results also suggest a surprising silver lining in a warming world. The study found that hurricane size growth rates do not change much with global mean warming, though global temperatures continue to rise.
The 2024 Atlantic hurricane season gave a striking example of why storm size matters. Hurricane Helene expanded rapidly before making landfall, ballooning into one of the largest storms in U.S. history at an estimated width of over 400 miles and causing unprecedented damage.
“Two hurricanes with the same maximum wind speed can be two very different sizes,” Wang said. “But think of one doughnut the size of South Carolina and another the size of Texas.”
Chavas compared the process to popcorn kernels in a pan. “The hurricanes see the tropical ocean like popcorn heated on an uneven pan — turning up the heat everywhere may make them pop a little faster, but it’s over the hot spots where the hurricanes will pop the fastest.”
Modern satellites provide high-quality, daily estimated measurements of sea surface temperatures worldwide. By applying this new understanding of how hurricanes respond to local ocean hot spots, forecasters may be able to better predict how large storms will become at landfall.
“A larger storm has a larger footprint of damaging winds, generates higher storm surge and over a larger area, and produces more rainfall — all greater risks to society,” Wang said. “Better predictions of storm size at landfall translate to better predictions of the hazards that pose risks to life and property.”
The Chavas lab at Purdue specializes in understanding extreme weather, from tropical cyclones to severe thunderstorms and tornadoes. Wang focuses on the physics of hurricane structure, particularly storm size.
The team tapped into Purdue’s Rosen Center for Advanced Computing, which gave them the ability to analyze global data in fine detail and uncover patterns that would have been impossible to see otherwise. These resources helped ensure that their findings about tropical cyclone growth are both accurate and comprehensive.
They also used the National Center for Atmospheric Research’s Cheyenne and Derecho supercomputers, some of the fastest in the world, to run experiments that mimic how storms behave in different warming scenarios. This powerful combination of Purdue and NCAR computing resources let the researchers explore what-if questions about our climate and deliver insights that can improve forecasts and preparedness for future storms.
The findings pave the way for improvements in both daily storm forecasting and long-term risk assessment used by industries such as insurance and infrastructure planning. The research also highlights the importance of integrating theoretical science with high-resolution data and advanced computing power.
The work was supported by the National Science Foundation Division of Atmospheric and Geospace Sciences under grants #2431970 and #1945113.
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They also used the National Center for Atmospheric Research’s Cheyenne and Derecho supercomputers, some of the fastest in the world, to run experiments
I have to take issue with that. Computer simulations, models etc are not experiments:
Computer simulations are not experiments. There is a sharp distinction between computer simulations and models on the one hand side and experiments on the other hand side. Just like models and theories, computer simulations belong to the theoretical side of science as opposed to the empirical side which encompasses experiments, observations and experiences. – Eckhart Arnold
Not only is there a track record of data torture – and even pure invention, eg Met Office – there is a record of language manipulation to go with it.
Also there is no way to trackbhurricane size or strgenth over the 20th century.
Here are six reasons to assert that todays hurricanes are considerably over estimated when compared to past hurricanes, and how those storms were rated.
1. Dropsondes (Instruments dropped from hurricane hunter airplanes, guided by Doppler to be placed in the most intense part of the storm eye wall) cannot give the one minute sustained wind reading required to determine Hurricane classification, as they stay in a given guest far longer than a fixed instrument…
…“Turbulence studies have demonstrated that Lagrangian (parcel) wind measurements are inherently smoother than Eulerian (fixed-point anemometer) measurements (Gifford 1955), with dominant periods longer by a factor of about 3–4 (Angell et al. 1971)”.
2. The “surface” readings have considerable variance, and are often “modeled”. And that is controversial, with considerable debate on how best to do that. Currently the high side of the model is, unsurprisingly, ascendant…
“Powell and Black (1990) recommended that an adjustment factor of 63%–73% be used to reduce 700-hPa wind speeds to the surface, based on comparisons of flight-level and buoy data (again, mostly outside of the eyewall). Operational practices at the National Hurricane Center (NHC) have varied over time; in recent years surface winds have typically been taken to be 80%–90% of the flight-level wind”
That is a very large difference where a 100 mph at altitude wind can be considered to be from 62 to 90 mph at the surface. Also individual storm profiles are known to be highly variable, so no one model is right.
3. Modern hurricane readings predicted storm surge is often considerably over-modeled to actual results. As an example… ” October 4, 1842 – A 955 mbar major hurricane which made landfall on northwestern Florida produced a 20-foot (6 m) storm surge at Cedar Key. Strong winds result in severe damage in Tallahassee.” (This is almost double Helena’s peak 10.5’ storm surge, also at Cedar Key.)
4
The Safirr Simpdon scale used to categorize hurricane strength for wind damage (excluding storm surge, spin off tornado damage, and rain flood damage), consistently shows observed damage one to two categories below how today’s hurricanes are rated. Past storms do match Saffir Simpson scale damage, as this, beyond the occasional well placed anemometer readings, was the actual method used to classify hurricanes, along with observed storm surge records.
5. Modern media is very coy with exactly how the category estimates are made, and seldom if ever releases links to the actual flight readings taken right at landfall. Also, by the time the eye wall hits land, close to 50 percent of the storm has already been on land for some time, and the storm is already weakening.
6. At landfall, especially in a storm like Milton with the eye wall broadening and breaking up, a hurricane hunter aircraft, guided by Doppler radar, will place the dropsconde directly in the strongest part of the storm, and get the highest wind speed possible, fail to confirm sustained wind speed, and get the lowest pressure reading possible. While everything happening on land is considerably less. This makes a huge difference in rating a storm. This site illustrates that message very well. https://www.ventusky.com/
Go to the site site and watch a time series for Hurricane Milton. Scroll through the time bar for the storm as it approaches land fall. Note how broad the eye becomes, and more importantly, even as the eye wall hits land, the most intense parts of the storm are all offshore on the west side, and southwest side. With the eye evenly split over land and sea, all the strong readings are on Gulf side of the storm, and over the water, and the difference in wind speed to anything over the land is profound.
On the Vetusky site, set for 10 m surface winds, the highest reading, on the west and southwest ocean sides of the storm is 155 Kph, and over land it is 95 kph. (96 and 59 mph respectively) Now a hurricane aircraft is going to drop the dropsonde right in the strongest part of the storm, not over land, and, as mentioned, that will not give one minute sustained winds. In addition, while a well formed eye tends to have the same barometric pressure throughout the eye, a reforming eye, or a collapsing eye like with Milton, will have variable pressure, and again, guided by doppler, the hurricane hunters will read the lowest pressure part of the storm.
So we have no idea of the multi decadal change in hurricanes.
Maue’s data goes back to 1980; at least some of the 20th century.
Yes, but not wirh tge same methods as outlinrd
David,
I think you are correct. The idea from Purdue University that the larger the size of hurricane, the stronger the wind is wrong. From a physics point of view the more you try to spin something that gets bigger inertia comes in, especially from a rough sea surface. It would seem from the past that the most powerful hurricanes or cyclones were not really large and had small eye centres with intense pressure and thus were rotating faster, the lowest being something like 873 mbs.
A lot of nonsense was published about a cyclone in Australia in 2011, called Yasi which was supposed to have reached Cat 5 but no actual wind was recorded above a gust of 185 k.p.h and a central pressure of 930 mbs. The town of Innisfail some 35 miles away had little damage, something not consistent with a Cat 5 cyclone. Pressure systems are far more likely to control hurricanes than water temperature.
I have actually flown through the eye of a Cat 3 cyclone in a DC9 and the eye was about 10 miles across. Quite smooth conditions at 23,000′ as we climbed through it and it was transitioning to Cat 4 soon after. Earlier that evening the wind across the strip at Gove in Northern Australia was around 45 knots in driving rain but it was the pressure system causing those winds not the temperature. Your comments about surface readings are probably correct regarding modelling.
I meant friction there, not inertia
Story tip: Blade Running
In the Scottish port town of Irvine in Aryshire, almost 80 of Britain’s oldest wind turbine blades lie disused in an old warehouse. Thirty years ago they towered 55 metres above the South Lanarkshire countryside, powering Scotland’s first commercial windfarm at Hagshaw Hill. Today, they wait for a green energy breakthrough of another kind: blade recycling.
…
The race to find a way to recycle old turbine blades needs to progress apace. By 2030 Europe is expected to dismantle about 14,000 wind turbines, creating 40,000-60,000 tonnes of blade waste, according to WindEurope. Germany alone will account for approximately 23,300 tonnes, followed by Spain with 16,000 and Italy with 2,300.
The US wind power industry is expected to follow suit. – The Grauniad
The waste problem is way bigger than they thought, way, way bigger than nuclear…
Would those blades meet the definition of “single use plastics”?
They should…
There are several (4, 5, …) components in a blade that are not plastic, such as fiber glass, carbon fiber, and balsa wood.
Single use plastic fits the little bottles that medicines come in. {I often re-use the plastic bags that I get at grocery stores.}
1152937801938171040.jpeg (1440×1440)
I wonder how they get money for this fiddling when the science was settled more than two decades ago. Cyclones will get worse in a warming world all caused by human emissions of CO2.
Surely it is counterproductive to still pay some scientist challenging the science.
Cyclones will get worse in a warming world.
I’d like to hear Michael Mann explain this in terms of his fabled global warming. He does claim to be a premier climate scientist, after all.
Take Jupiter – a rather cold world by our standards at -110C (-166F, 163K) – and its famous Great Red Spot. Its windspeeds are speeding up.
Researchers analyzing Hubble’s regular “storm reports” found that the average wind speed just within the boundaries of the storm, known as a high-speed ring, has increased by up to 8 percent from 2009 to 2020. In contrast, the winds near the red spot’s innermost region are moving significantly more slowly, like someone cruising lazily on a sunny Sunday afternoon.
The massive storm’s crimson-colored clouds spin counterclockwise at speeds that exceed 400 miles per hour
https://science.nasa.gov/missions/hubble/hubble-shows-winds-in-jupiters-great-red-spot-are-speeding-up/
Can’t blame Jowetts.
Nice theory Rick. But storm data does not show an increase in either intensity nor number of hurricanes in recent decades; at least since 1980. Measuring the weather is never counterproductive. Theorizing about it often is.
Poe’s law may be needed here.
This has always seemed intuitively obvious. I’m surprised it took scholars so long to confirm it. 😐
Kind of struck me as a “No schist, Sherlock.” moment as well. As I understand it, it is in general the temperature differential, not the absolute temperature, that drives violent weather.
‘This has always seemed intuitively obvious.’
I fully agree. The fact that it is not obvious shows a remarkable lack of understanding of how tropical storms work.
So yes, warm water pools, at temperatures above 26C, can fuel dramatic increases in the rate of water evaporation, the energy that drives storms, when a wind storm passes over and triggers the phenomena described above.
And how do warm water pools form?
Nothing to do with CO2
TV weather folks know about hurricane strengthening over warm water…we’ve heard it said many times…must be lost knowledge like how to build big stone walls out of big stones….
Only as usual it is not that simple.
I should have written it down when it happened (because I’ve got advanced CRS), but I remember several years ago there was a hurricane moving towards the east coast of the US, and much ink was expended on the fact that the hurricane was going to encounter some very warm water before it hit the coast, which would supposedly “supercharge” the storm.
I liked that situation…a prediction that could be evaluated right after it was made. As the storm moved into the coast in this “warm surface water” that was going to “supercharge it,”…
It fizzled.
So much for that generalization.
Perhaps ocean hot spots are also needed for the formation of hurricanes – at a hotspot air rises more rapidly than elsewhere forming a rising column of moist air that begins to circle because of coriolis force. No hot spot but just uniformly warm ocean surface and all that happens is widespread thunderstorms but no focus for hurricane formation. Is that what is happening this year?
‘Modern satellites provide high-quality, daily estimated measurements of sea surface temperatures worldwide.’
Are these the same modern satellites that ‘measure’ down-welling radiation at the Earth’s surface?
Are we talking out the 1/100th of a degree warming stuff that keeps giving us “the hottest year evar!” You know, mathematical averaging from bad stations and homemade algorhithms?
“But the factors behind that difference were not well understood. Wang and Chavas showed that the rapid growth of storms is tied to “hot spots” in the ocean. These are localized areas where the water is significantly warmer than the surrounding tropical waters.”
I always thought that the warmer waters and increases in hurricane strength was a fact.
The Gulf of America formerly known as Gulf of Mexico is usually very warm in August September.
That is the peek of Gulf hurricane season and the peak of the most violent storms.
Software codes are not required the explain it.