Ike a Cat-3 at landfall in Texas?

[wxman57]

I am not sure Galveston would have had 25 feet had Ike not contracted before landfall. maybe 15 instead of 12. Wher ethe surge would have been MUCH higher though would have been the Beaumont/Port Arthur area. They could have seen 20 instead of the 12 that they received

That's correct. Frictional effects from the sea bottom (shoaling) is a significant factor in surge height. Galveston Island (not the bay) is much less prone to surge than most of the Louisiana coast and the MS coast because the water offshore is deeper. There's less of a shoaling effect. Ike would have produced about twice the surge it did had the center struck the mid LA coast or SE LA because the water there is shallower.

I was measuring Ike's Radius of Max Winds (RMW) in the hours prior to landfall. The RMW dropped from about 80nm to 40nm in the 6-8 hours prior to landfall. This shrinking of the wind field spared Beaumont/Port Arthur a harder hit and focused Ike's strongest wind and highest surge into Bolivar Peninsula to High Island. Had Ike's wind field contracted more, then a higher surge would have been experienced in eastern Galveston Bay, perhaps 3-5 feet higher. If the Ike's RMW had moved ashore directly over Galveston Island (center moved inland on the southwest end of the island), then the surge over Galveston Island may have been only a few feet higher.

Effect of Shoaling on Surge Height (Shoaling Multiplier):


In no way was Ike a Cat 3 hurricane at landfall. No observation supports that. And that 111 mph wind that keeps rattling around was labeled as a GUST, not a sustained wind. Channel 39 in southwest Houston just 5 miles north of my home recorded a 112 mph gust. It's interesting to note that the mean sustained wind during Ike's passage was low-end TS winds (40 mph) in both the graphic below and the one posted for Galveston. It just goes to show you how much the wind varies over time with the passage of a hurricane. The wind can be blowing at 40 mph one minute and 80 the next.

KTXH Ch. 39 in SW Houston:



I've received a number of detailed charts of Ike's surge from Jeff Lindner at Harris County Flood Control District.

Ike's Surge Heights:


Peak 21.2ft Surge North of Texas City in western Galveston Bay:

[jinftl]

I am curious....was it a dramatic shrinking of the windfield or was the windfield that was so widely publicized over open water and not what would result over land due to friction

...or is there a misunderstanding of the 'up to' miles from the center distance that is given for hurricane and ts winds?

For example....Ike was 35 miles from Galveston, advisory states hurricane force winds (and i assume...another possible source of error....that this means sustained winds of hurricane forece) were up to 120 miles from the center, yet Galveston was "only" reporting gusts to hurricane force. The HRD analysis does not support a 240-mile wide diameter of hurricane force winds over land. Not even close.


From NHC advisoy

AT 1200 AM CDT...0500Z...THE CENTER OF HURRICANE IKE WAS LOCATED
NEAR LATITUDE 28.9 NORTH...LONGITUDE 94.5 WEST OR ABOUT 35 MILES...
55 KM...SOUTH-SOUTHEAST OF GALVESTON TEXAS AND ABOUT 80 MILES...130
KM...SOUTH-SOUTHWEST OF PORT ARTHUR TEXAS.
.

DATA FROM NOAA DOPPLER WEATHER RADARS AND RECONNAISSANCE AIRCRAFT
INDICATE MAXIMUM SUSTAINED WINDS ARE NEAR 110 MPH...175 KM/HR...
WITH HIGHER GUSTS.

IKE REMAINS A VERY LARGE HURRICANE AND HURRICANE FORCE WINDS EXTEND
OUTWARD UP TO 120 MILES...195 KM...FROM THE CENTER...AND TROPICAL
STORM FORCE WINDS EXTEND OUTWARD UP TO 275 MILES...445 KM. DURING
THE PAST HOUR...HURRICANE FORCE WIND GUSTS HAVE BEEN REPORTED ON
GALVESTON ISLAND AND REPORTS FROM NOAA AND AIR FORCE RECONNAISSANCE
AIRCRAFT INDICATE SUSTAINED HURRICANE FORCE WINDS ARE JUST OFFSHORE
GALVESTON ISLAND.

[wxman57]

I am curious....was it a dramatic shrinking of the windfield or was the windfield that was so widely publicized over open water and not what would result over land due to friction

...or is there a misunderstanding of the 'up to' miles from the center distance that is given for hurricane and ts winds?

For example....Ike was 35 miles from Galveston, advisory states hurricane force winds (and i assume...another possible source of error....that this means sustained winds of hurricane forece) were up to 120 miles from the center, yet Galveston was "only" reporting gusts to hurricane force. The HRD analysis does not support a 240-mile wide diameter of hurricane force winds over land. Not even close. ... snip

First of all, don't make the assumption that I said the wind field was shrinking. I was speaking of the RMW decreasing - the distance of the PEAK winds from the center. Hurricane force winds still extended quite far from the center. And don't assume that because the NHC mentions hurricane force winds extending out to 120 miles from the center that it means 120 miles from the center in all quadrants. That was only the NE quadrant. Wind radii were less to the west of the center. Finally, those wind radii apply only to marine exposure. Expect a good 15-20% reduction in wind (at least 1 SS category) when the winds touch land. That's why no Cat 2 winds were measured inland (and the fact that power went out to most anemometers).

Oh, and finally, finally, the statement of hurricane force winds extending "out to 120 miles from the center" means just that. It doesn't mean that hurricane force winds exist everywhere within 120 miles of the center in whatever quadrant the NHC is speaking. That's just the peak distance that hurricane force winds could extend from the center. A hurricane's wind field is by no means uniform in each quadrant. Each quadrant is populated by areas of heavy squalls and other areas of relatively lighter winds. So it's easily possible to pass through that 120 mile radius and not see hurricane force winds if the heaviest squalls don't hit your location.

[jinftl]

Please forgive me if it sounded like i was questioning you...not at all...but it did trigger a thought i have had with alot of storms....the wind radius at landfall and inland not equating to the 'up to miles from the center' number given by the NHC. I think you hit the nail on the head...up to 120 miles from the center doesn't mean a circle of 120 miles in radious drawn around the eye.

This is something that is reported incorrectly by media...on the friday night of ike, even The Weather Channel was saying areas 120 miles away from eye....a wall of 240 miles...would see sustained hurricane force winds. Interesting. CNN was reporting a 600 mile swath of tropical storm force winds would hit land. Neither panned out...thankfully. Certainly not an ike-only phenomenon.

I am curious....was it a dramatic shrinking of the windfield or was the windfield that was so widely publicized over open water and not what would result over land due to friction

...or is there a misunderstanding of the 'up to' miles from the center distance that is given for hurricane and ts winds?

For example....Ike was 35 miles from Galveston, advisory states hurricane force winds (and i assume...another possible source of error....that this means sustained winds of hurricane forece) were up to 120 miles from the center, yet Galveston was "only" reporting gusts to hurricane force. The HRD analysis does not support a 240-mile wide diameter of hurricane force winds over land. Not even close. ... snip

First of all, don't make the assumption that I said the wind field was shrinking. I was speaking of the RMW decreasing - the distance of the PEAK winds from the center. Hurricane force winds still extended quite far from the center. And don't assume that because the NHC mentions hurricane force winds extending out to 120 miles from the center that it means 120 miles from the center in all quadrants. That was only the NE quadrant. Wind radii were less to the west of the center. Finally, those wind radii apply only to marine exposure. Expect a good 15-20% reduction in wind (at least 1 SS category) when the winds touch land. That's why no Cat 2 winds were measured inland (and the fact that power went out to most anemometers).

Oh, and finally, finally, the statement of hurricane force winds extending "out to 120 miles from the center" means just that. It doesn't mean that hurricane force winds exist everywhere within 120 miles of the center in whatever quadrant the NHC is speaking. That's just the peak distance that hurricane force winds could extend from the center. A hurricane's wind field is by no means uniform in each quadrant. Each quadrant is populated by areas of heavy squalls and other areas of relatively lighter winds. So it's easily possible to pass through that 120 mile radius and not see hurricane force winds if the heaviest squalls don't hit your location.

[CrazyC83]

That 111 mph recording was indeed a gust. But it does help in making the observation that when the reading is put in comparison to the HRD analysis map, that 111 mph was nowhere near the maximum wind field. The maximum winds would have been 20 miles to the east where there were no observations. Generally speaking (based on advisories), 95 kt gusts translate into sustained winds of around 75 kt, and based on the HRD maps, winds were about 20 kt higher on land (and 30 kt higher over water) over McFaddin NWR.

If the map-position comparison is used, Ike's landfall intensity was 105 kt. However, even I think that is a bit on the high side since it is not backed up by radar or the aircraft. 100 kt is what I would put it at (backed up by some aircraft observations). However, no populated area saw any Cat 3 winds, even if that is indeed the intensity (and not that many saw Cat 2 winds).

[jinftl]

From dialogues such as this on other storms, I know there is a tendency for folks to get 'fired up' and defensive because it sounds like the intensity or trauma of the experience they went through is somehow being diminshed. This could not be further from the truth...what this post-storm wind analysis shows is that sustained winds of 74 mph are so much more intense than most people would think. Any community that endures sustained winds of that level will no doubt bare the scars on both the natural (tree canopy especially) and manmade (roofs, windows, signs, traffic lights, power lines) fixtures of their day to day life.

It also really calls into question how 'overrelied' upon the Saffir Simpson scale. Ike hit as a Cat 2 but practically no area in Texas saw what amounted to a 'textbook' Cat 2 experience. Sustained winds were more in the strong tropical storm and Cat 1 levels while surge was in the Cat 3 or higher level in some areas.

I guess what I wonder is....how would Houston (or fill in the blank with another city on the coast) prepare and react if a Cat 1 with a windfield identified as twice the size of ike approached? If people were told (outside of surge zone), they would experience sustained Cat 1 winds, would they brush it off becayse Ike was a '2' and not prepare as much?

At the end of the day...frustations and expenses put aside, it is still better to be 'overprepared' than under. An example of a ridiculously vulnerable community that almost paid the price for underpreparation would be Key West with Wilma. From what I have read, Wilma tracking 20 miles or so further south, and the deathtoll from surge drowning could have surpassed that of Katrina in MS and LA because most people did not comply with evacuation orders.

[Aslkahuna]

Based upon a study done by JTWC on gust ratios, it was determined that the typical gust ratio for a hurricane over water was about 1.25 from where we get the familiar forecasts of 100G125kt 140G170, etc. we see on the advisories. The same study, however, indicated that the overland gust ratio for a landfalling hurricane was more like 1.5-1.6 hence you could get 95 kt wind gusts from 63 kt sustained winds or 150 mph gusts from 100 mph winds. It's important to realize this. Also, the definition of sustained wind is an average wind over a set period of time (one minute in the US, 10 minutes elsewhere). Overland, winds in an hurricane are extremely turbulent due to frictional and obstructional effects so although you may have a sustained wind of 60kt with gusts to 90kt, the actual windspeed may vary from under 40kt to 90kt. It was 34 years ago, but that is what I saw on the wind trace for Typhoon Irma at Clark AB when we had 60G83 kt it was one broad swath across the wind roll. Unless you actually display a running wind trace on a monitor from a digital readout, you will not see this. For those who have never seen a wind roll trace from a recording anemometer, in high wind situations they strongly resemble a seismograph trace of a strong earthquake.

Steve

[Ptarmigan]

From my experience in Ike, we mostly got TS winds with hurricane force. Most areas got 50 to 90 mph winds and they are loud. Sounds like a cross between being in a subway in New York and car wash at a gas station and try that for 12 hours! It was a scary ride for me personally and I NEVER want to experience another hurricane. Think of being tortured with large needles slowly being inserted into you. It is torture. Standing with hurricane force winds is very hard, let alone 50 mph winds. I would never stand with a +111 mph wind. I would get blown away and end hitting some building and die.

[Ed Mahmoud]

It was darned windy, but not having been in many hurricanes, I have no way of really judging how strong it was.


I was impressed the following day we still got some manly wind gusts, well after the storm had apparently let up.

[hurricanetrack]

A few feet higher surge on Galveston Island would have been enough to send the Gulf in to the first block of homes/businesses. It was darn close as it was- and in some places, the Gulf did top the Seawall and come across. I wish for science's sake that Ike hit during the day. We had enough cameras put up in stationary locations to record the worst of the conditions that we really could have had something to study. As it stands now, our Bermuda Beach cam is the best overall. For those who have not seen it, check out the time lapse of that cam:

http://www.hurricanetrack.com/videogall ... lapse1.wmv

Our other cameras farther east on the island worked flawlessly but it got dark and so we could not see the worst of the surge. This is why the Bermuda Beach cam stops- and because the tape was only 9 hours long. We had to place it and turn it on early due to the flooding already taking place on the west end. That is going to be our #1 mission next season- to come up with at least one set of powerful lights to run during one of these night-time events. Still, even with something, it will not mimic daylight enough. One day though, we'll get a full day time landfall of a monster hurricane. We had it with Katrina but lost the equipment in the surge, as many of you know already.

[jinftl]

From my limited experience with storms...the most recent being katrina and wilma over south florida...and comparing that to what i see when the tv news folks are outside reporting live from a storm (vinyl raincoat required of course...in spite of dewpoints probably being 75), there is no way tv news crews are out there with winds sustained over 80mph in all likelihood. Possibly quite a bit less. The physical challenge on the body plus the danger of debris-filled air is not anything a human being could place themselves in and still be able to report 'live'.

Again, not intending to diminish anyone's storm experience...actually quite the opposite...if you have had 75 mph sustained winds where you live...even 65 mph with gusts to strong Cat 1... you have been through 'you know what' of an experience.

It was darned windy, but not having been in many hurricanes, I have no way of really judging how strong it was.


I was impressed the following day we still got some manly wind gusts, well after the storm had apparently let up.

[MiamiensisWx]

If you want to observe an example of an immense, intense hurricane, check the 1926 Miami hurricane in southern Florida. The radius of 1-min hurricane force winds was extremely large. The wind radii, angle of approach, 20-25 mile eye diameter, and the northern eyewall's proximity to Fort Lauderdale/Hollywood resulted in severe winds in Broward County. The strongest winds extended from Pompano Beach southward. Palm Beach County and northern Broward County received sustained winds of Category 1 intensity; Fort Lauderdale/Hollywood likely received isolated Category 2 winds (85 kt/100 mph) in some locales.

Here are some photographs from Broward County.

Fort Lauderdale:

http://www.cyberattic.com/stores/pasttreasures/items/669971/item669971cyberattic.html

http://www.cyberattic.com/stores/pasttreasures/items/670199/item670199cyberattic.html

http://www.srh.noaa.gov/mfl/newpage/fort_lauderdale_arcade.jpg

http://www.sun-sentinel.com/news/local/southflorida/sfl-hurricane.1926.4,0,3873763.photo

Hollywood:

http://www.cyberattic.com/stores/pasttreasures/items/670186/item670186cyberattic.html

http://www.srh.noaa.gov/mfl/newpage/hollywood_casino.jpg

http://www.srh.noaa.gov/mfl/newpage/hollywood_damage.jpg

In Broward County, wind damage is very similar to Wilma, and some areas appear to have received damage slightly more severe than Wilma's peak destruction in many locations. This hurricane was very large and intense (145 mph/933 mb)... if you didn't examine this event, you would have likely believed that the TC made landfall closer to Broward County. The actual landfall point was Coral Gables (south of Miami).

[wxman57]

The gust factor in tropical cyclones is by no means standard. Much stronger winds typically exist a few hundred to 1000 feet above the surface. At any time, perhaps in/near heavier convection, these winds can dip down to the surface for brief periods. This could result in gusts approaching twice the sustained wind. Lili (2002) and Rita (2005) produced such wind gust ratios. Their surface winds dropped off significantly prior to landfall but that energy (i.e, strong wind) was still above the surface.

I've toured the area from High Island to San Luis Pass and there just isn't any evidence of Cat 3 winds. Ike was a Cat 2 at landfall, and probably a lower-end Cat 2 with 95-100 mph winds. This is very important, as it shows that the term "major hurricane" is very misleading. Any hurricane can have a major impact on an area if it has a large area of hurricane-force winds.

[jinftl]

I believe that is the education that needs to be gained from this analysis...not that the intensity of the winds (or any other facet of a storm) are being understated in post-storm reviews...but that damage can take place with any storm category, and even Cat 1 winds can leave a huge mark on a community.

Getting the public to understand this may be the best defense against the 'just a cat 2' reasoning the next time a storm threatens...esp if you only experienced cat 1 winds!

I've toured the area from High Island to San Luis Pass and there just isn't any evidence of Cat 3 winds. Ike was a Cat 2 at landfall, and probably a lower-end Cat 2 with 95-100 mph winds. This is very important, as it shows that the term "major hurricane" is very misleading. Any hurricane can have a major impact on an area if it has a large area of hurricane-force winds.

[vbhoutex]

Ike at CAT3 at landfall? Who knows? I say this not because I experienced Ike and his fury, but I've always found a frustration in these arguments(not that this one is an argument compared to some that have been discussed here)because there is really no good accurate easy way to make the "final" determination. It is similar to tornados being call EF1 or EF3, etc. If a tornado has EF3 damage anywhere in its' path it is called an EF3 even though that damage could have been in one block out of 100 that the tornado traversed while the rest was EF0.

Tropical cyclones are pretty much determined the same way, but have much larger windfields and a lot less chance of the actual highest winds being caught by an anemometer since they are really few and far between(as opposed to tornados being chased by DOW radar etc. at every corner). Unfortunately, even with the advanced and advancing technologies we have to measure winds in tropical cyclones there is almost no way that the probable actual highest surface winds experienced will be captured by an instrument that is definitely calibrated correctly and can definitely be trusted. Maybe someday we will truly know what the highest surface winds recorded in a TC are, but I don't see it anytime soon.

I also have to go along with those that say we have to get away from the "it was only a CAT2" mentality. Having experienced the number of TC's I have in my life I bristle when I hear that Ike(put any name here)was only a CAT2 when I see first hand the lives that have been altered in this region forever, much less when Camille(probably "only a CAT4") occurred or Katrina (probably only a CAT3")occurred. The rating is not what matters!! It is the devastation of lives that matters. I have seen the damage to property and lives at all levels from TC's and no matter what the level the TC it is devastating damage to many quite often. I am not sure what the answer is to get EVERYONE to be as aware of TC's and their capabilities as most of us are, but until some way to educate ALL we will continue to here the same old (see above). JMHO. Off the soapbox now. Whew!!
I've said my piece elsewhere in these forums on the need for some sort of surge classification or wording to be added to warnings that will get attention. If I have heard it once from survivors or Ike or othe storms with major surge I have heard it too often that "it was only going to be a CAT?". Back off the soapbox again.

[hurricanetrack]

The shoaling factor that Wxman57 shows in his post is interesting to say the least. It explains a lot for me as I was in Gulf Shores, AL for Ivan and saw enormous waves coming in where as with Katrina and Ike, the waves were not as large but the surge spread out more.

I am curious, is there such a graph for the Atlantic and specifically the Southeast? I would assume the areas of the Georgia and SC coasts would have some serious shoaling from hurricanes and the Outer Banks of NC and the southeast FL coast would not.

Fascinating stuff for sure. We'll have plenty to keep us busy in the off-season- studying all of the data, info and accounts of Ike and Gustav.

[wxman57]

The shoaling factor that Wxman57 shows in his post is interesting to say the least. It explains a lot for me as I was in Gulf Shores, AL for Ivan and saw enormous waves coming in where as with Katrina and Ike, the waves were not as large but the surge spread out more.

I am curious, is there such a graph for the Atlantic and specifically the Southeast? I would assume the areas of the Georgia and SC coasts would have some serious shoaling from hurricanes and the Outer Banks of NC and the southeast FL coast would not.

Fascinating stuff for sure. We'll have plenty to keep us busy in the off-season- studying all of the data, info and accounts of Ike and Gustav.

The U.S. Navy Shore Protection Manual that I got the shoaling data from does go all the way up the East Coast, but it's a small B&W chart in the book. I took the data from the book and put it into Excel to make the Gulf Coast graphic above. If I remember correctly (book is at work), the area from Jacksonville to Savannah is fairly vulnerable to surge, though not like LA/MS or Tampa would be. Eastern Florida has a multiplier of 0.3 or 0.4, I believe - deep water offshore. I won't be in the office again until Jan 2nd, can check then.