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Larry strikes Australia

By: Dr. Jeff Masters, 2:57 PM GMT on March 20, 2006

Tropical Cyclone Larry roared onto the coast of eastern Australia Sunday near the town of Innisfail as a major Category 3 hurricane with sustained winds of 118 mph and gusts to 180 mph. Although no deaths or serious injuries were reported, Larry caused tens on millions of dollars in damage to structures and crops in a part of Australia unused to seeing severe tropical cyclones. Innisfail is a popular jumping-off point for tourists heading to the Great Barrier Reef, and Larry will be a severe blow to the economy. The reef itself suffered a direct hit from the cyclone, but the extent of damage is unknown.

Larry may be the strongest tropical cyclone in recorded history to hit the east coast of Australia. The north coast and west coast of Australia are more prone to major hurricanes, and just last year Tropical Cyclone Ingrid hit Croker Island in the Gulf of Carpenteria off the northern coast of Australia as a Category 3 hurricane of strength similar to Larry.

Figure 1. Tropical Cyclone Larry at landfall in Australia.

As bad as Larry was, the media coverage I saw yesterday on several news web sites was over-hyped. All of the major media reports I saw called Larry a Category 5 storm with winds up to 180 mph, and one report said it could become "Australia's Katrina". What they didn't mention was that Australian tropical cyclones are ranked by the Australian severity category, a one to five ranking system based on the maximum wind gusts of a storm. A storm that has wind gusts in excess of 174 mph (280 km/h) is classifed as a Category 5. In the U.S. Saffir-Simpson scale that we are familiar with, the strength of a storm is based on the sustained winds, not the gusts. Tropical Cyclone Larry at landfall had 118 mph sustained winds, which made it a low-end Category 3 storm on the Saffir-Simpson scale--Category 3 sustained wind speeds range from 111 to 130 mph. Larry's lowest pressure was 925 mb (same as hPa, hecto-pascals, which the Australians use as their pressure unit). Katrina at its maximum intensity had maximum sustained winds of 175 mph, with gusts to 215 mph, and a minumum pressure of 902 hPa (mb).

The Southern Hemisphere tropical cyclone season runs November through April. The waters in the Southern Hemisphere oceans have reached their peak temperatures, and are now starting to cool. There is another storm, Tropical Cyclone Wati, that is near the Australian Coast in the same region as Larry stuck, but Wati is expected to recurve out to sea and weaken over the next three days.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Hyped, maybe, but I think the report of a storm "dissipating over land" with 100kt winds counts as "understatement". :-)
Thanks for the information Dr. Masters, and glad to see that it was not as bad as the media were making it out to be. I'm wondering why different countries use different scales to rank hurricane severity?
You might know that the wind speed of tornadoes is measured in 3 second wind gusts, so why not hurricanes - a wind gust that is 50 % higher than sustained winds is over 2 times more destructive (energy = mass * velocity^2). By the way, also notice that my link says that 180 mph gusts is equivalent to an F4 tornado on the EF scale, and the maximum gusts of Katrina (215 mph), Rita (around 220 mph) and Wilma (around 230 mph) were well into the F5 range on the EF scale. This also explains Andrew's incredible wind damage.
it is wild to think that the big hurricanes pack the same wind intensity as tornadoes, but over a vastly larger area.
I remember when Ivan hit us, the NHC had recorded sustained winds of 150mph and gusts fo 170mph on their reports. But private weather stations, boats etc reported recorded in excess of 200mph, although I this was generally hearsay.
Still you generally know a Cane is coming your way. I would not fancy the short warning you get for a tornado.
Yes, it is the pulsing effect of storm winds which do the damage. Like the wolf, huffing and puffing until your house comes down..
Hurricane winds can accelerate from a constant 60mph to 120mph and return to 60mph in just a few seconds, and I've never been around for a Cat3 or above. The winds blow in one direction as the storm approaches, and in the opposite direction as it leaves. If the storm is wet, or the area has had lots of rain prior to the storm's approach, then everything is loosened up already. Trees (and dwellings) will bend and screech and hang on during the constant winds. It's the gusts which take them away.
Yeah, for double the damage, the winds would go up 1.4 times.
Final advisory while it's still a hurricane...lol

wtps31 pgtw 200900
ampn/ref a is a tropical cyclone warning.//
Subj/tropical cyclone warning//
1. Tropical cyclone 17p (larry) warning nr 010
02 active tropical cyclones in southpac
Max sustained winds based on one-minute average
warning position:
200600z --- near 18.0s 144.0e
movement past six hours - 255 degrees at 14 kts
position accurate to within 040 nm
position based on center located by satellite
present wind distribution:
Max sustained winds - 075 kt, gusts 090 kt
dissipating as a significant tropical cyclone over land
repeat posit: 18.0s 144.0e
12 hrs, valid at:
201800z --- 18.5s 141.7e
Max sustained winds - 040 kt, gusts 050 kt
dissipated as a significant tropical cyclone over land
200900z position near 18.1s 143.4e.
Tropical cyclone (tc) 17p (larry), located approximately 120 nm
west-southwest of Cairns, Australia, has tracked west-
southwestward at 14 knots over the past six hours. Tc 17p is
rapidly weakening over Mainland Australia. This is the final
warning on this system by the Joint Typhoon Warning Center
signs of regeneration. Refer to tropical cyclone 18p (wati)
warnings (wtps32 pgtw 200900) for twelve-hourly updates.//
Having experienced the eye of Wilma this year in Ft. Lauderdale, I found it interesting in that the winds do fluctuate up and down, but at some point the "sustain winds" become very intense and maintain that strength for quite some time...that is when you know you are in the "real" thing. Even in Wilma (cat 2) that moment becomes very obvious as compared to before and after fluctuations as the storm approaches. The trees, etc. took on that "horizontal" look and maintain it for at least 20-30 minutes on both sides of the eye...my wife and I retired to an interior room at that point and just waited it out. I've gone through a number of storms being a life-long So. Florida resident (and one cyclone in Vietnam) and Wilma put "the fear" in me...you begin to believe the house can't take too much more ...All the efforts to categorize the forces of nature with 1-5 scales come up a little short when you are sitting in your living room saying those little prayers we all say...I'm sure those in a tornado feel the same. The #2 doesn't sound too bad, does it? Try sitting through one!!
gcain..I can imagine just where you're coming from. I've experienced these storms, since I've lived in the Keys and the Panhandle, but I'v never been in a location where the eye came over. I can not imagine a sustained wind over 100 mph. It must be quite horrifying!
We only got one side of the eye of Ivan, but enough. Sheltered on the top floor of a 4 story building (not the best idea I know) with windows all round to watch. (at the time of shelter we didn't know it was going to go over us).
Between the rivers of rain, especially between the buildings, watched palm trees and bushs ripped up and blown, amazing to see. Some of the debris was moving so fast it was blur. You could actually feel the building swaying side to side in the gusts when you lay down.

Moved down a couple of floors when the metal lining on the roof ripped off (that was a scary noise). Lucky I did shelter though as my 1 floor flat was completely washed through by the surge.
I've heard any number of times that wind damage actually goes up as the third or fourth power of wind velocity, not just the square. Fluid dynamics, though, makes it pretty clear that force (drag) goes up as the square of velocity. Maybe the higher figures consider secondary effects -- for example, if the force of the wind is enough to break a window, the structure's coefficient of drag suddenly increases, and it can lead to a catastrophic failure.
jeffb..get this mental picture; the windows break, but the dwelling is framed to stand 125+ winds. The water/wind coming into the house through these orifices is like sticking a half dozen pressure washers inside a house, and directing the spray over every square foot of the interior. Drywall becomes drywall mud in a half hour!
Yes, very few people realize a 90mph wind throws things with 9 times the momentum as a 30mph wind.
I can tell ya, if you don't believe in God before you sit out a hurricane, you sure as H--- do afterwards! I cracked the porcelain off one of my crowns during Hugo, I was chattering and shaking so hard! LOL I can laugh about it now, but when one starts taking aim at me since then, I skitter off out of town faster than my namesake!
Hype or Not

Accuweather (or should we say $$$ weather) predicts Northeastern Hurrciane this season


For the record of the current topic, strongest winds I ever experienced 1st hand where somewhere between 100 - 105 during a hurricane party (ie I was drunk and "pretending to be a kite" during a cat 2 hurricane) when I was younger.

Unless you want to count the F2 torondo that brushed the trailer I was in...

Like Murphy said "There is no such thing as an atheist in a foxhole."
globalize, run that bit about momentum by us again please? I'd never thought of it, but if I remember my high school physics then yes, I think I remember momentum does go up as a square of the increase in velocity?! Yikes!
I made it through at Cat 2, Frances, in 2004. Seemed as the winds were stronger than that but I didn't have any tool to measure the winds, just took the word of the local weather folks.

Yeah, snowboy..the momentum of moving objects (on earth) is measured exponentially, by the product of the square. A car moving at 50mph does not hit the tree with 5 times the force as one which hits the tree at 10mph, but 25 times the force!
Momentum is mass times velocity so it goes up linearly with velocity. Kinetic energy is half of the mass times the square of the velocity so it goes up as the square of velocity. A 150mph wind will exert twice the force of a 75mph wind but a piece of flying debris will do 4 times as much damage at 150mph than at 75mph.
Who is Frank Lepore of spokesman with the National Weather Service and why is he miss-informed with the catagory of Larry?

The highest recorded winds for Cyclone Larry, a category 5 storm, were about 180 miles per hour (290 kilometers per hour), compared with 125 mile per hour winds for the Category 3 Katrina when it struck land, said James Vasilj, a spokesman with the National Weather Service in New Orleans.

``If a Category 5 hurricane like Larry hit any populated area of the United States, the damage would be absolutely catastrophic,'' said Frank Lepore, spokesman for the National Hurricane Center in Miami.

``You're talking major wall failure on high-rise buildings. A Category 5 hurricane could lift a 2000-pound car and deposit it on a 4-foot-high wall,'' Lepore said in an interview. ``A 150-160 pound person wouldn't stand a chance.''

gippgig..don't those laws only pertain to a vacuum? I was only referring to objects with mass. But wind in a hurricane is not only moving objects having extreme mass and density ie. cars & houses, but also O2, N, and H20, which also have some mass.
globalize wrote:

jeffb..get this mental picture; the windows break, but the dwelling is framed to stand 125+ winds. The water/wind coming into the house through these orifices is like sticking a half dozen pressure washers inside a house, and directing the spray over every square foot of the interior. Drywall becomes drywall mud in a half hour!

Okay, that's another geometric factor for "damage". :-) I was thinking, though, about that fact that an intact surface is more aerodynamically "slippery" than a structure with holes, and so wind at a given velocity will exert more force on the second than on the first. A building framed to withstand 125mph winds when intact might well be torn apart by those same winds once the windows or doors give way.

(BTW, "exponential" in X means going up by some number raised to the power X, not going up by X raised to some power. If force goes up as the square, it's geometric, not exponential.)
gippgig wrote:

Momentum is mass times velocity so it goes up linearly with velocity. Kinetic energy is half of the mass times the square of the velocity so it goes up as the square of velocity. A 150mph wind will exert twice the force of a 75mph wind but a piece of flying debris will do 4 times as much damage at 150mph than at 75mph.

No, a 150mph wind will exert four times the force of a 75mph wind, because each unit of air (gram, liter, cubic ft, whatever) will have twice as much momentum, but you're being hit by twice as many units of air per unit of time, right?

I, unfortunatly have been through Frances, Jeanne and Wilma. Wilma deffinatly took the cake for structural and large tree damage in West Palm. Amazing how much glass can bow during a big gust. I also never knew how quick I could jump up off the couch and into the hallway either.
The NHC guy saying that is inexcusable...come on...
That's some bloomer to make
From the PalmBeachPost.com Who Are The NHC Forecasters?

Frank Lepore, age 62, public affairs officer
Years at Center: 10
Function: A walking information bank of facts about hurricanes; helps the media get accurate information to the public.

Experience: Worked in movie and TV production for the Army for 20 years; handled public affairs for Secretary of Defense and Joint Chiefs; also served as combat photographer in Vietnam.

Education: Undergraduate degree from the College of William and Mary; master's in education from the University of Florida.

Storm story: While sailing the western Pacific in a World War II Liberty ship in 1964, he ran smack into 35-foot waves generated by a typhoon. 'I've never been that sick in my life. I lived on crackers and wedges of oranges for about three days.'

Special talent: Able to field 1,300 e-mails and hundreds of phone calls from the media as storms approach.

On hurricanes: Viewed from space, 'They really are things of beauty. But as I left the center as Jeanne was about to make landfall, I really had the sense that there was a living beast out there.'
last comment just a FYI Follow-Up...
jeffB, I think you're right.

Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity
Carlos D. Hoyos 1*, Paula A. Agudelo 1, Peter J. Webster 1, Judith A. Curry 1
1 School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA USA.

To better understand the change in global hurricane intensity since 1970, we examine the joint distribution of hurricane intensity with variables identified in the literature as contributing to the intensification of hurricanes. We use a methodology based on information theory, isolating the trend from the shorter term natural modes of variability. Results show that the increasing trend in number of category 4 and 5 hurricanes for the period 1970-2004 is directly linked to the trend in SST; other aspects of the tropical environment, while influencing shorter term variations in hurricane intensity, do not contribute substantially to the observed global trend."

The above is the first 100 words of an electronic article which I received from Scienceexpress.org last week. The full article should be coming out in Science Magazine, but of note is the finding that the increased frequency of Cat 4 and 5 storms is directly related to increased sea surface temperature. (SST)
I'm still going on record with the prediction that weather will happen tomorrow. The CSE says it, therefore it must be so.
Lol caneman!!!
Hey, we are doing a "just for fun" contest on my blog. Post the date you think Alberto will form. I will then post your prediction in my blog and we will see who wins
Doctor Masters, can you site a reference that the Australian tropical cyclone scale uses gust speed rather than sustained speed?


This seems to contradict that statement.
PS: This speaking as someone who has a close attachment to Babinda which caught the brunt of the force, and a house I stayed at there had the roof ripped off, and as yet unknown other damage.
Sorry, I should do more research before I point any fingers. http://www.bom.gov.au/catalogue/warnings/WarningsInformation_TC_Ed.shtml

Using the gust factor on post 36, gusts over ocean of 280km/hr indicate 121 knot 1 minute mean wind speed which is still a Saffir Simpson catagory 4. When you use different metrics for scales it can make things aharder to compare, and I will of course defer to the resident expert :P
kerneld~ this is from Dr Master referece link above & off the same site you posted. Scroll down about a 1/4 of the page. One the page you linked, it's showing the comparision to other scales.
oh ~all good, ya figured out... all part of learnin:)
skepony...what is the latest long range GFS forecast saying? Last week it said that Florida should look out for a storm on 3/31.
Thanks Skyepony. Still, the Australian news reports say gusts of up to 290 km/hr, now I am not sure if they are looking at the strongest gust recorded, or the strongest gust within a certain time frame. Again using the Australian BOM gust scale factor (Which is just an approximation I know) I come out with 1 minute sustained wind speed of 125 knots which is well in to Category 4. Where did wunderground get its 113 knot 1 minute mean wind speeds from for its storm track? Just curious.

We lived through Ivan - every hospital in Pensacola damaged, the Three Mile Fishing Bridge destroyed, the I-10 eastbound bridge over Escambia Bay knocked out and under repair and Perdido Key was turned into a war zone.
How often do Hurricanes hit the east side of the island? I dont think I recall ever seeing one on that side of the old island there.
SMU88~That was an early April fools joke by the model, it looks. Hasn't shown much like it was for a few days now.

Credit Bureau of Meteorology and Emergency Management Australia.Research has shown that cyclones in the Australian region exhibit more erratic paths than cyclones in other parts of the world. A tropical cyclone can last for a few days or up to two or three weeks. Movement in any direction is possible including sharp turns and even loops.
Like other South Floridians.....Wilma here......you don't ever forget the sound of your roof being "torn" off your house...and the anxiety of water pouring in....seemingly everywhere......
"Where did wunderground get its 113 knot 1 minute mean wind speeds from for its storm track? Just curious."

They got it from the Joint Typhoon Warning Center. Those were not 1-minute speeds, they were ten, Wunderground just uses the feed from the JTWC, and the JTWC uses 10 minute averages. They disgracefully under-rated Larry at peak, according to them he was a 75kt storm when he really came to our attention, and was never better than 100kt.
Oh yeah ~ that was Monday, weekly ENSO report...

credit NOAA
La Nina's still on & healthy...
Looks to be strengthening a bit, 1&2 are definetly falling.
I want to emphasize that I am retracting my statement that a 150mph wind exerts twice the force of a 75mph wind. The statement about flying debris stands.
Hopefully SE FL can squeak out some rain later this week, almost to extreme drought levels.
"near the town of Innisfail as a major Category 3 hurricane with sustained winds of 118 mph and gusts to 180 mph"

* Cyclone Larry passed directly over the top of the town of Innisfail, not 'near'.

* Innisfail is also several miles inland from the coast. More accurate readings of peak winds from Larry, would be obtained from Mourilyan Harbour, South Johnstone, Etty Bay or Cowley Beach, all right on the coast, compared to Innisfail. There were no measurements of sustained winds for TC Larry, but estimates were 200 km/h (125 mph) sustained winds, & peak gusts of 180 mph (290 km ph). The air pressure dropped to 915 mb (<27.17 inHg), which is consistent with a high category 4 or low category 5, on the SSS, not category 3.

Wikipedia quote:

Due to lack of measurements, Larry's 1-minute sustained wind speeds, either for the storm's peak intensity or from landfall, are not known. It is therefore unknown where on the Saffir-Simpson Hurricane Scale (which is based on 1-minute sustained winds) the cyclone would fall. Larry's wind gusts are generally consistent with a Category 4 storm... The cyclones minimum pressure, however, is more consistent with a Category 5 hurricane.

According to sources I read, (Noaa, NHC), Katrina had a minimum air pressure at landfall of 918 mb, although it was much lower than that, when a hundred miles or so, out to sea. I have also seen references that state because Katrina was well above 920 mb when it made a 2nd landfall on the Gulf Coast, that it was only a high cat 3 or low cat 4. Personally, 918 mb would qualify Katrina as a low category 5, in my view. This is not to belittle Hurricane Katrina in any way, which was an horrific event, that claimed 1,600 lives & wrecked NOLA & the Gulf Coast.


The reference to TC Larry being the worst storm since 1931 made by NZ media, is also wrong. The previous worst cyclonic storms in Queensland were in January 1918 (Mackay) & March 1918 (also Innisfail).