new ivan landfall info... no cat 4

[Aslkahuna]

I believe that Mark and his crew were on the Alabama side and hence caught only the weaker northern eyewall segment. He can correct me if I'm wrong but that's the impression I got. Incidentally, this whole thing is not new as in the 70's we had questions about the reported storm intensities versus the actual wind reports in the Philippines. Of course, part of that was due to the fact that the Filipinos reported 10 minute average winds while JT was forecasting 1 minute average winds but there were still disparities even then.

Steve

[Stormsfury]

I believe that Mark and his crew were on the Alabama side and hence caught only the weaker northern eyewall segment. He can correct me if I'm wrong but that's the impression I got. Incidentally, this whole thing is not new as in the 70's we had questions about the reported storm intensities versus the actual wind reports in the Philippines. Of course, part of that was due to the fact that the Filipinos reported 10 minute average winds while JT was forecasting 1 minute average winds but there were still disparities even then.

Steve

Steve, I believe you are correct. If memory serves me correctly, Mark was in Gulf Shores, AL.

SF

[Sanibel]

Having watched the radar image landfall I estimated that Orange Beach received the main NE eyewall impact just east of Gulf Shores. What his reading confirms is that the main wind headwall dispersed to the right of the landfall as an unwinding storm does. This probably occurred in harmony with a surge peak.

The center landfell in Palmetto Beach about 7 miles west of Gulf Shores. Gulf Shores should have received winds close to the upper range of Ivan simply because it took a punch of eyewall winds that never touched land up til then. Too bad because he could have served a better function if he had parked his van over in Pensacola...


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[Aslkahuna]

Well, at the time he was positioning his equipment, the forecast had the eye making landfall even further west with the eastern eyewall over or along the eastern shore of Mobile Bay and hence closer to his location. But it skittered a bit to the right and so Gulf Shores got a weakening northern eyewall sector while the strongest eyewall sector set up to the east of there.

Steve

[MGC]

Just was looking at a book at Barnes and Nobles titled Extreme Weather. It is a pretty good book covering not only US weather extremes but worldwide. In it, Camile is listed as haveing a verified sustained wind in Boothville La at 172mph or 149kts. Boothville was on the west or weak side of Camile. So, imagine the winds in the RFQ of Camile. No way will Camile be downgraded.......MGC

[Derek Ortt]

other factors have to be taken into consideration regarding that reading, such as elevation of the wind. If that wind is just 100 feet above the ground, the surface reduction is only 80 to 85 percent.

The expectation is that Camielle will get a downgrade, but remain as a category 5 hurricane

[Anonymous]

other factors have to be taken into consideration regarding that reading, such as elevation of the wind. If that wind is just 100 feet above the ground, the surface reduction is only 80 to 85 percent.

The expectation is that Camielle will get a downgrade, but remain as a category 5 hurricane

Highly doubtful it will be any lower than 185 mph.

[SouthernWx]

While I don't believe hurricane Camille had sustained winds of 190 mph (165 kt) at landfall as many hurricane books and websites state, I do firmly believe they were in the same intensity as Mitch at it's peak....175-180 mph (155 kt) sustained, with gusts exceeding 200 mph, and likely as high as 210-215 mph (or gusts equivalent to a low end F4 tornado). Although the Fujita scale wasn't operational in 1969, structural engineers stated in their report that wind damage...even 30 miles inland away from the coast was consistent with a major severe tornado (and measured gusts reached 135-140 mph nearly 100 miles inland near Columbia, Mississippi...F2 intensity).

At peak intensity in the GOM, Camille was likely even stronger....with sustained 185 mph winds or more (160 kt). We must remember this wasn't a large hurricane....at landfall, hurricane force winds only extended 45-50 miles from the center of Camille. With an eyewall so tight, and central pressure in the 905 mb range, it's likely Camille was close to hurricane Allen's intensity (Allen 899 mb/ 165 kt).

When hurricane Allen reached the western GOM in August 1980.....recon aircraft reports indicate sustained winds of 180 mph (155 kt) with a central pressure of 909 mb -- the exact landfall pressure recorded by private wx observers at Camille's time of landfall on the Mississippi coast.


PW

[Derek Ortt]

Perry,

here is something that is going to be considered by HRD during the re-analysis. The flight level back then was almost always 850mb. For many storms, the forecasters used the 850mb winds as the SURFACE winds, which we now know is dead wrong and that the surfac ewinds are about 80 percent of the 850mb winds and 90 percent of the FL winds.

With this being said, if Camielle's FL winds were 170-175KT, yielding about 190-195 m.p.h., this equates to about 160 at the surface, still a category 5, but a little lower than Andrew's of 165, which a paper in next month's BAMS (I believe it is next month's, shouldnt have been drinking when I found this info out) says is likely a very conservative value wince they are using data from an hour before landfall to determine the landfall intensity, neglecting the 10mb drop in pressure that occurred after the final recon flight

[MGC]

So Derek, you are saying that Camile will likely be reduced in intensity below Andrew? Despite Camile having a pressure at landfall nearly 13mb lower? There had better be some extrodinary new information to convince me that Andrew had stronger winds than Camile.....MGC

[SouthernWx]

In all honesty Derek, I sincerely hope HRD utilizes more than just the sporatic recon flight level data available. Only three eye penetrations were made into hurricane Camille between western Cuba and U.S. landfall...and the last several hours before landfall on the Mississippi coast; due to the C-130 aircraft experiencing the loss of an engine and being forced to return to Houston, TX where an emergency landing was made.

I hope someone also takes into consideration the small diameter of Camille's eye (11 miles) and compact eyewall at time of landfall. I know there are WSR-57 radar images of Camille available, from New Orleans (LA) and Jackson (MS) because I've seen and studied them. Also, the 909 mb central pressure and 24-25' storm surge should have some bearing on intensity; as should Herbert Saffir's post-storm engineering analysis of the wind damage.

A small, compact 909 mb hurricane is certainly consistent with 155 kt...based on hurricanes such as Allen and Mitch. Also, that 909 mb (26.85") reading was by two PRIVATE citizens....taken near the west end of the Bay St Louis bridge. In a hurricane as small and compact as Camille, if they were only 1 or 2 miles from the exact center of the eye....that could mean the true central pressure was several millibars lower.

Just a few points to consider, which I'm certain a man of Dr Chris Landsea's integrity and experience will do.

PW

[Derek Ortt]

There are two reasons why pressure means squat when determining the winds and why it cannot be used.

1. The change in pressure over the change in distance (dp/dn), along with the radius of curvature is the key term in determining the wind speed based upon the gradient wind equation. A smaller storm has a tighter pressure gradient and a smaller -(fr)/2 reduction that is made to the quadratic portion of the equation

full equation is -(fr)/2 +- (((f^2*r^2)/4)-r*(dp/dn))^1/2

p=phi=geopotential=g*dz

with the large ridge north of andrew, and with andrew being smaller than Camielle, I would not be the least bit surprised that Camielle had weaker winds than Andrew.

Also, if there was an eye wall replacement cycle, like with Floyd, there may only be a 4-6 mb pressure rise, but a temporary 30KT reduction in wind speed. Thats how Floyd hit Eleuthra as a 105KT hurricane, but with a 929mb pressure

[Stormsfury]

I noticed the gap between pressure fixes and at the time of the lowest barometric pressure fix, the winds were ONLY 140 kts ... IMHO, Camille's winds at LANDFALL to be around 155-160 kts with the slightest of landmass effects (pulling in SOME drier air along the western flank on northerly winds, however, with Camille's compact size (as stated before) and moving over an area where the actual Gulf Stream current begins and runs SE thru the Florida Straits ... PK intensity, IMHO, more than likely was 165 kts ... and the pressure most definitely lower than 905 mb ... more like 895 mb (IMHO and estimation) ...

Now, let's quantify something here...with the SLIGHTEST amounts of drier air, this would theoretically add some punch to the wind gusts capable in Camille ... and again, IMHO ... gusts topped out at 190-195 kts ...

Code: Select all

August    16  18 UTC   24.2N  86.5W   310 deg    8 mph  12 kph   150 mph 240 kph   908 mb   Major Hurricane - Category 4 
August    17   0 UTC   25.2N  87.2W   330 deg   12 mph  20 kph   160 mph 260 kph   905 mb   Major Hurricane - Category 5 
August    17   6 UTC   26.0N  87.7W   330 deg   10 mph  16 kph   180 mph 285 kph    -- mb   Major Hurricane - Category 5 
August    17  12 UTC   27.0N  88.2W   335 deg   11 mph  18 kph   185 mph 295 kph    -- mb   Major Hurricane - Category 5 
August    17  18 UTC   28.3N  88.7W   340 deg   14 mph  24 kph   190 mph 305 kph    -- mb   Major Hurricane - Category 5 
August    18   0 UTC   29.4N  89.1W   340 deg   12 mph  20 kph   190 mph 305 kph   909 mb   Major Hurricane - Category 5 
August    18   6 UTC   30.7N  89.6W   340 deg   14 mph  24 kph   115 mph 185 kph    -- mb   Major Hurricane - Category 3