new ivan landfall info... no cat 4

[Derek Ortt]

camielle's wind are expected to be lowered during the re-analysis. I highly doubt that Camielle came in with 155KT winds, probably closer to 135-140KT.

With Andrew, we had hard recon data suggesting a solid cat 5. The cat 4 rating was based upon science that was believed to be correct, but was proven wrong a few years later. That is the only reason why the upgrade was made, due to improvements in the alrorithm computing 700mb flight level vs surface winds. Using the SAME algorithm used during Andrew yields 104KT at landfall for Ivan.

As for Opal Storm, if you want to criticize the studies findings based upon them missing aspects of the hurricane thats fine, but you are just throwing around allegations, calling them liars, showing zero intelligence doing so. Even NHC didnt discount those findings, they just said narrow streaks may have had cat 3 winds

[Opal storm]

Derek,the wind devices in Pensacola broke when the eye-wall was hitting Pensacola.Most of those devices were made to survive sustain winds of 120mph,if i'm right 120mph is a cat3.So how did they fail when there were only cat 2 winds?

[DoctorHurricane2003]

we had hard recon data suggesting a solid cat 5. The cat 4 rating was based upon science that was believed to be correct, but was proven wrong a few years later.

Exactly.

[Droop12]

Im kind of stuck on what I believe occured. Derek, you do great analysis and its hard to disagree with you because of that. I think the SS Scale really needs revised because according to you I guess its crap for determining wind and surge values around here. I think the easiest thing to do is measure the strength of hurricanes the same way you do tornadoes based on the damage they produce. But even that would have its flaws.
IMO, if I was to base the wind damage using the desciptions on the SS scale, I'd place it at a Cat 3. The descriptions match perfectly. Surge on the other hand is hard to determine. I dont think a 3, no matter what angle it hit the coast, could destroy I-10. But if surge was near 15-20ft. along with the 115/120mph southerly winds along with the enormous waves being funneled up the bay....That makes more since to me. I think the surge was near this level because it was already built way up due to the time Ivan spent as a 4/5 in the gulf. Obviously a strengtening 2 or 3 isnt going to have 40-70ft waves, but in a weakening 5/4 their already built up and their not going to drop as soon NHC says so. Thats my idea on the surge and wave, and why they were both abonormally high.

[Derek Ortt]

droop,

what you said rings so true. 2 years ago with Lili, it weakened to a borderline 1/2, yet it had a 12 foot storm surge because the surge didnt fully die out. Ivan may have been a 4 as soon as 60 minutes before landfall, but then the shear and dry air got it, along with the interaction with land, and really weakened the thing very rapidly just beofre landfall

[Derek Ortt]

some kid Chris Landsea? Prehaps he'd love to find out what it is you said. Last I checked, he has a PHD, unlike John Hope. Besides, Hope said 190 before James Franklin's 1998 paper, which showed the precise reduction factors to use

[SouthernWx]

Let's see...where do I begin?

So Derek, you state hurricane Camille's maximum sustained winds at landfall were only 135-140 kt?

Well, I have a letter recieved from NHC hurricane specialist (retired) Robert Case in 1989, in which both he and former NHC Director Robert Sheets estimated Camille's max sustained winds at landfall at 155-160 kt.

I had written asking Dr Sheets for a comparism between hurricane Gilbert, hurricane Camille, and the Labor Day hurricane (Bob Case said that in both Dr Sheets and his estimation, "hurricane Camille likely supported sustained winds similar to Gilbert {155-160 kt} because of the small diameter of Camille, even though the central pressure was higher). They also estimated the Labor Day hurricane may have had 165-175 kt (190-200 mph) sustained winds at landfall due to the exceedingly small diameter of the hurricane.

Also, I was fortunate enough to meet the late John Hope on several occasions while he was the tropical weather specialist at The Weather Channel here in metro Atlanta.
John was a forecaster at NHC during Camille, and said by far it was the most intense hurricane during his career there. He estimated sustained winds in Camille of 175-190 mph (155-165 kt)...with gusts over 200 mph (175 kt), based on the extreme structural damage AND USAF and USN aircraft data.

See Derek, I may not have a college degree, but I began researching Atlantic hurricanes before you were even born....1975. I have a lot of data on hurricane Camille; some I found while researching libraries and WSFO office archives from Mississippi to south Florida; other information that NHC forecasters sent me over the years.

During the final aircraft recon mission into hurricane Camille, only a few hours before landfall on the Mississippi coast (and while nearing the Mouth of the Mississippi river), the aircraft measured flight level winds of 180 kt....207 mph. Using today's standard 10% reduction, that equals 162 kt at the surface....186 mph.

I've also seen radar images of hurricane Camille at time of landfall, and the similarity to hurricane Andrew is striking, even on old WSR-57 radar. There was no evidence of eyewall replacement....not when Camille was passing east of Venice, LA....nor at time of landfall. It was a small, tight, very intense eye and eyewall that crossed the Mississippi coast west of Gulfport that night.

I also have studied the post-hurricane engineering survey for Camille, conducted by Herbert Saffir. His estimation was hurricane Camille's sustained winds at landfall were far in excess of any landfalling hurricane he'd ever surveyed...in the period 1947-1969. That includes the great Florida hurricane of September 1947, hurricane Hazel, hurricane Audrey, Donna, and Carla...all cat-4's at landfall. Mr. Saffir also stated "the wind damage associated with hurricane Camille was consistent with that of a severe tornado, even inland away from the Gulf of Mexico".

IMO, there's no way hurricane Andrew's sustained winds were stronger than Camille's at time of landfall. Andrew's wind damage was catastrophic....Camille's was even worse. Even almost 100 miles inland from the Gulf coast, there were confirmed, measured wind speeds of 120 mph sustained, with gusts of 135 mph (on a private anemometer near Columbia, Mississippi)....and the anemometer failed at 135 mph. It's estimated winds gusted even higher (and Camille didn't race inland as Opal or Charley did....only moving NNW-15 mph or so).

In regards to hurricane Ivan, as I stated earlier....I AM NOT AN AMATEUR. I likely know as much regarding past U.S. hurricanes as some of your buddies at AOML/ HRD. About three years ago, a veteran NWS forecaster told me I knew more about past Atlantic hurricanes than he did....more than his entire staff. After three decades of living, breathing, and caring about nothing but severe storms; studying about them, even late into the night...I should know what I'm talking about.

I was in Mobile, Alabama in September 1979...chasing hurricane Frederic. I saw that wind damage firsthand....and Ivan's IMO is just as severe. If Frederic was a strong cat-3 at landfall (and I believe firmly sustained winds were 110 kt...125-130 mph), then Ivan was also.

I'm not boasting, so please don't take it that way....but just after hurricane Andrew made landfall, I stated that IMO the sustained winds were considerably stronger than the 140 mph estimate by NHC (later upgraded to 145 mph in the preliminary report). I estimated at that time sustained winds in the north eyewall of 150-160 mph, with gusts possibly reaching 180-200 mph....based on the damage I witnessed, satellite presentation at landfall, and the extreme pressure gradient of such a small, intense hurricane. This "uneducated weenie" with years of dedicated wind speed and storm research was much closer to the mark than NHC, based on the data available at that time.

If I didn't firmly believe hurricane Ivan was stronger than Opal at time of landfall, and in the same intensity range as Frederic, then my friend....I'd never risk my reputation by posting it.

PW

[Derek Ortt]

I'm not contesting Camielle being a cat 5 at landfall, it most definately was.

To determine whether or not Camielle had winds stronger than Andrew, I would need a couple of things. 1. Was there a trough to the west that was approaching. If so, the winds could be the same or weaker than Andrew due to the gradient wind equation, the same would be ture if there was an eye wall replacement cycle. I have never seen the data from Camielle, so I cannot know this for sure.

Also, a note about recon data from before 1998. There was no consistency used by NHC, each different forecaster used a different method. Miles Lawrence always used strictly 80 percent no matter the flight level, with Avila used 90 percent of 700mb, while some even used 100 percent of 850mb. Franklin's work completely changed the way things are understood and brought consistency. I'll check out the findings on Frederic right now to see what the 115 is based upon

I cannot wait for the re-analysis to be completed (though I'd settle for the 35 hurricane right now as our local AMS chapter needs that info for a 70th anniversary of that terrible storm)

[Sanibel]

Using the SAME algorithm used during Andrew yields 104KT at landfall for Ivan.

I'm confused here Derek. Are you saying Ivan was 104KT at landfall? Isn't that around 120mph and a category 3?



The reason I don't buy into the failing sensor explanation is because a private weather station on North Captiva registered a gust of 178mph during Charley and never failed as far as I know. Common sense tells me this private meter was not any better that the several military-grade stations around Pensacola. I would find it hard to believe that a US military weather sensor failed at 120mph or less while a private rooftop station clocked 178mph and held.

This defies common sense because we don't have any officially-recorded winds higher than 89mph as far as I know. I'm sure the naval stations in Pensacola have back-up batteries and generators for their instruments. So saying they lost power doesn't wash either. I'm also not buying that every sensor in the Pensacola region failed. It just doesn't wash. It probably makes sense to compare the actual windspeeds of other storms and the rate of sensor failure associated with them - where, when, and at what windspeed. My guess is that this expected failure pattern won't translate to Ivan and that higher winds would have been recorded.


So where we are at this point is having to explain high wind damage with low wind readings. Derek claims it was due to duration of event. I'd have to see a second study on it...


.

[Matthew5]

I have to agree with Southernwx he knows what is talking about. As for the greatone he doe's bring up good points. We should respect his option. That is why this board is here to discuse this.

[Derek Ortt]

that 104 is if you use the true 90 percent reduction; however, there is some research indicating that the reduction is closer to 80 percent for weakening tropical cyclones, which would yield closer to 95KT.

Have just checked some of the reports from Frederic and the total equipment failure wont hold water as in Frederic, the maximum recorded gust was 126KT on the Dauphin Island bridge and another gust to 119KT before failure at another location

[SouthernWx]

Derek, the synoptic pattern that allowed hurricane Camille to become so intense, and maintain that extreme intensity was unusual. There was a deep upper trough over the central plain, but being mid August, it wasn't advancing rapidly eastward. Camille moved NW to NNW through the Gulf of Mexico between the trough and a ridge of high pressure with the western end of the ridge oriented from near Cape Hatteras to Grand Cayman Island. That's why all the objective analysis available forecast a track more northward once the hurricane reached the western tip of Cuba.

The deep upper low setup produced a strong southerly jet to the west of Camille while in the Gulf, and this enhanced the outflow....assisting intensification.

With the oceanic heat content of the Gulf....and excellent enviromental conditions over and around the hurricane (as John Hope called it "perfect conditions for a monster hurricane"), it's possible....IMO probable that Camille never dropped below cat-5 intensity the entire time it was traversing the Gulf of Mexico. In fact, with the lack of recon eye penetrations...it's quite possible the true peak intensity may have been below 900 mb.

PW

[MGC]

This is a great thread. Now on to Camile. The damage I witnessed from Camile was that of some F-4 tornadoes (Brandon Ms, Nov 1992 and Moore OK, 2003). Homes were totally destroyed, as in splinters just like big tornadoes do. I can only assume that the wind intensity was equal to an F-4 tornado. Having witnessed first hand the damage caused by several other Cat 3 hurricanes, and my experience of following hurricanes over 40 years, I am confident that Ivan was a Cat 3.

Excellent post SouthernWx.....MGC

[Droop12]

Great post Southern Wx and Derek. Got a question for ya Derek. What observation is used to officially classify a hurricane...Surge, Sustained winds, or pressure? They hardly ever align enough to make an accurate classification, using the SS scale. Lili for example, Cat 2? at landfall based only on windspeed and pressure, but surge was very high due to its previous strength. Does the NHC only classify systems based on windspeed? My local meteorologist said if he classified Ivan based on surge and wave height, it'd be a borderline 4/5. But the wind would only be a marginal 3. I agree with him, winds around 115 with some major gust, especially associated with small tornadoes or vorticies spinning around the NE eyewall. By the way, anyone know the official lowest pressure? I heard it was near 945mb in Baldwin County.

[Matthew5]

Droops, the level of "cats" a hurricane is based on is its one minute winds speed. Surge or anything else is not what a hurricane or any tropical cyclone is based on what so ever. 39 to 74 mph is a tropical storm...While a hurricane is above 74 mph...Surge means nothing because the hurricane can be a cat5 over the southern Gulf. But that doe's not mean it is not going to have a big surge when it makes it to the coast as a cat1 or 2!

Pressure doe's not tell how strong a hurricane is because the pressure normally falls before the winds pick up.

I believe that Ivan was a soild cat3 hurricane.

[Droop12]

I agree totally with you MGC about Camille. I've did alot of research on her, and tried to locate as many pics as I could. I was unfortunate enough to witness the damage caused by an F-3/F-4 tornado east of Indianapolis, IN. When I first saw pictures of the damage from Camille I thought WOW, looks just like the damage I saw after the tornado rolled through. IMO, her damage was comparable to and upper F-3, weak 4. I'd say 185mph with gust to 210 sounds about right for Camille. I know I never would stay for a hurricane that strong. Its almost like certain death if your in a house near water. If your not near the water your house will just be picked apart by the 185mph winds.

[Aslkahuna]

I don't know about the Navy Weather Stations nor if the Air Force procedures have changed but we would have a real problem with typhoons at Clark AB in the Philippines. The Control Tower people had control over which wind sensors were in use. During a storm, whenever we went into Condition X-Ray they would close the field and the tower personnel would leave the tower and as they did so they would turn off all electrical equipment INCLUDING the wind sensors. During Irma in 1974, I sent them back up to turn the sensors back on and we were able to record the highest wind gust recorded at Clark since WWII but in my opinion we missed the strongest winds of the storm based upon what happened in our building prior to the wind sensors coming back. If these procedures are still in place then that would explain lack of reports. Sensor failure doesn't necessarily mean that the anemometer is destroyed, the mast could be tilted or toppled or water gets into the circuits or, depending upon how the exhaust system for a backup power supply is designed water can get in and drown the generator (that happened to us at Clark during Irma and Kim). Even if the sensors are working, you still have to have the capability to get the data out or there simply will be no reports-most smaller airports and even many military installations now have civilian contractors taking the observations and I suspect that when the field closes so does the weather station-hence no observations during the peak of the storm. The only way to be certain about the actual winds recorded at a station is to examine the archived wind data and hope that if it's digital data that the sampling interval is less than three seconds-otherwise, you will oftentimes miss the real peak winds-best to have a sampling interval of no more than one second. Then there's the matter of sensor calibration but that's another story.

Steve

[Sanibel]

That's exactly why this doesn't make sense. I doubt the weather stations along the coast were all evacuated and their sensors shut-off. Somewhere out there somebody had to record a sustained wind higher than 89mph. Until I see a report claiming that the military station turned its power supply to the instruments off or that their generator was flooded I'm going to assume 90mph was all they got...



.

[Droop12]

Sanibel, You cant just assume that the highest winds during Ivan were only 89mph because its the only report you've seen. That was reported in Gulf Shores right? The strongest winds associated with Ivan hit between Gulf Shores/Orange Beach and Pensacola. Meaning reports from Pensacola and Gulf Shore most likely are not the strongest winds that occured. Im pretty confident that I expirenced winds sustained over 100mph (in Pensacola) the night of landfall. I probably expirenced gust near 140 judging by the hundreds of snapped trees and power poles in the area. No minimal cat 1 or weak 2 is going to pull a stop sign out of the ground and mangle it and blow it onto the roof of the building i stayed at. (I kept it as a sovenir lol) Both the sign and its metal pole were bent in odd shapes. A few blocks from where I stayed was a new gas station with a new, large awning. It was completly shredded and looked almost exactly like the one in Mike Theiss' video from Port Charlotte. Im not saying that Ivan had winds as powerful as Charley, just comparing damage. I think max sustained winds most likely were near 120mph near the water in western escambia county, eastern baldwin county. 100+mph in pensacola and about 80-90mph in gulf shores. So heres my final thinking, 115-120mph max sustained winds, with a surge of mainly 15 to possibly near 20 ft in a few unlucky places. I say possibly 20 ft because I've seen a few houses on 12ft stilts that arent there anymore.

[iceangel]

Opal of 1995 also reached Category Four status at peak intensity.

As I recall, for a short period of time, Opal was a cat 5 when she was down near the bay of campechee. She also started racing up to the area(21MPH) It was in the early morning hours and I was still awake while this was occuring, In fact, my Aunt called us at 6:00 in the morning and said a cat 5 hurricane was coming right at us..for us to come to her house.