Landfall intensity of Ike

[CrazyC83]

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I know there is some question on how strong Ike was at landfall. I am looking through all the known data and here is what I have found:

Flight-level winds: The highest report in the last couple hours before landfall was 109 kt in the northeast quadrant. That translates to 98 kt at the surface. In addition, there were reports to 95 kt in the SW quad - the weakest part of the storm.

SFMR: The SFMR had a lot of weird reports in the flights leading up to landfall. Due to problems with it at times (the highest readings was 90 kt in the SW quad in the second-last flight), I am discarding it.

Dropsondes: They were up and down, but the last ones before landfall supported 90-95 kt. Some earlier supported 95-100 kt.

Damage surveys: Difficult to assess due to the storm surge damage and lack of reports on the NE quad. Low-level damage in downtown Houston, about 50 miles inland, equates to low-end EF2 on the Enhanced Fujita Scale, which suggests gusts around 115 mph (100 kt). Those winds translate to sustained winds around 90 mph (80 kt) in Houston. Given that it was near the center of the storm, it can be assumed that winds were about 10 kt stronger on the eastern side - about 90 kt after about 3 hours on land. The coastal damage shown would be high-end EF2 or low-end EF3 (about 140 mph or 120 kt gusts), which would translate to sustained winds of about 100 kt, but it is unclear if that is due to winds or surge.

Doppler radar: After converting to surface level, Doppler radar supports an intensity of about 95 kt.

Surface observations: No NE eyewall wind observations near landfall as the area was not well-sampled. However, Hobby Airport - inland on the west side - reported 65 kt sustained winds. It is probable though that the highest winds were not measured. An eye observation confirmed that the central pressure had deepened to at least 951.6mb at landfall (per Galveston surface report) and may have been a bit lower depending on where on the island that was reported. I'll assume 951mb for the landfall pressure, which suggests Ike was slowly strengthening at landfall.

Conclusion: In my view, the landfall intensity was 100 kt. While there is conflicting data (some support it and some don't), the improving satellite signature, deepening pressure and fact that the strongest winds were on land at that time in an area with no observations suggest that they might have been a bit stronger at landfall than earlier reports, since it was clearly 95 kt at 0000Z. I estimate that it reached 100 kt at 0600Z and kept that intensity until landfall.

[Matt-hurricanewatcher]

I totally agree with you CrazyC83...Yeah the recon data might of gone up just short, but I strongly believe that a metal tube that is only inches in diameter is not going to catch the strongest winds within the cyclone. It is impossible, in say what you went otherwise. It is VERY likely that there was winds of 3-5 mph stronger some where within our cyclone. In that is just what I'm going to believe. The nhc all the time sets their winds higher just for this reason a lone...The chance that there could be stronger winds. I seen it and you have seen it, so don't slam me for pointing out a fact. This was just as likely a cat3, as Gustav was a cat3 over much of its time over the gulf.

[CrazyC83]

I totally agree with you CrazyC83...Yeah the recon data might of gone up just short, but I strongly believe that a metal tube that is only inches in diameter is not going to catch the strongest winds within the cyclone. It is impossible, in say what you went otherwise. It is VERY likely that there was winds of 3-5 mph stronger some where within our cyclone. In that is just what I'm going to believe. The nhc all the time sets their winds higher just for this reason a lone...The chance that there could be stronger winds. I seen it and you have seen it, so don't slam me for pointing out a fact. This was just as likely a cat3, as Gustav was a cat3 over much of its time over the gulf.

The flight-level winds actually supported a 100 kt intensity (as 98 kt would round up in most cases), but the radar did not and dropsondes jumped around.

[Blown Away]

IMO, the wind damage to the structures looked like Cat 1 wind damage with Cat 2 gusts. I don't know how to rate the surge, except it was very bad. Does not seem to be as bad as the predictions.

[MiamiensisWx]

IMO, the wind damage to the structures looked like Cat 1 wind damage with Cat 2 gusts. I don't know how to rate the surge, except it was very bad. Does not seem to be as bad as the predictions.

Have you glanced at the reports and photographs from Crystal Beach, Kemah, and other areas away from Galveston proper?

[WxGuy1]

I totally agree with you CrazyC83...Yeah the recon data might of gone up just short, but I strongly believe that a metal tube that is only inches in diameter is not going to catch the strongest winds within the cyclone. It is impossible, in say what you went otherwise. It is VERY likely that there was winds of 3-5 mph stronger some where within our cyclone. In that is just what I'm going to believe. The nhc all the time sets their winds higher just for this reason a lone...The chance that there could be stronger winds. I seen it and you have seen it, so don't slam me for pointing out a fact. This was just as likely a cat3, as Gustav was a cat3 over much of its time over the gulf.

The flight-level winds actually supported a 100 kt intensity (as 98 kt would round up in most cases), but the radar did not and dropsondes jumped around.

The standard reduction factor did not look to be valid for the vast majority of Ike's time in the Gulf. We saw time and time again that the SFMR and dropsonde sfc winds were considerably less than 90% of the FL winds. Estimating sfc winds from FL winds is difficult because the "rule of thumb" is just that -- a rule of thumb. Not all storms, and not all areas of a particular storm, see the standard 0.9 FL-SFC factor. The NHC noted several times in their discussions that the sfc winds were considerably weaker than the FL data suggested for whatever reason.

This is not to say that the storm wasn't Cat 3. The difference between 110 mph sustained and 115 mph sustained is not much and shouldn't matter too much unless you really want to say "See, all this damage was from a Cat 3" (not directed necessarily at CrazyC83, but some others I've read on this forum). Unfortunately, there aren't many sfc obs along the coast from Bolivar Peninsula to Port Arthur, a stretch of land that should have seen the strongest winds. Again, I'm NOT saying that this wasn't a 100 kt storm. However, if the only real evidence of a particular max wind is a "rule of thumb" FL-to-SFC reduction, when the SFMR and dropsonde data don't support it and hadn't supported the standard reduction factor previously, then I think it's dubious to make such a claim.

[Aslkahuna]

Also have to realize that Houston is 50 miles inland so the gust ratio is more likely to be 1.5-1.6 rather than the 1.25 for winds coming in directly off the water. For gusts to 115 mph this would equate to a sustained wind of 72 mph (77 mph for a 1.5 ratio) or slightly less than sustained hurricane force. Should be noted also that the 65kt sustained wind reported at Hobby was an estimated and not measured wind. That said given the obvious developments occurring with the storm as it approached landfall it is likely that a small area of 100 kt winds very likely did occur along the shoreline east of where landfall occurred.

Steve

[bob rulz]

I totally agree with you CrazyC83...Yeah the recon data might of gone up just short, but I strongly believe that a metal tube that is only inches in diameter is not going to catch the strongest winds within the cyclone. It is impossible, in say what you went otherwise. It is VERY likely that there was winds of 3-5 mph stronger some where within our cyclone. In that is just what I'm going to believe. The nhc all the time sets their winds higher just for this reason a lone...The chance that there could be stronger winds. I seen it and you have seen it, so don't slam me for pointing out a fact. This was just as likely a cat3, as Gustav was a cat3 over much of its time over the gulf.

The flight-level winds actually supported a 100 kt intensity (as 98 kt would round up in most cases), but the radar did not and dropsondes jumped around.

The standard reduction factor did not look to be valid for the vast majority of Ike's time in the Gulf. We saw time and time again that the SFMR and dropsonde sfc winds were considerably less than 90% of the FL winds. Estimating sfc winds from FL winds is difficult because the "rule of thumb" is just that -- a rule of thumb. Not all storms, and not all areas of a particular storm, see the standard 0.9 FL-SFC factor. The NHC noted several times in their discussions that the sfc winds were considerably weaker than the FL data suggested for whatever reason.

This is not to say that the storm wasn't Cat 3. The difference between 110 mph sustained and 115 mph sustained is not much and shouldn't matter too much unless you really want to say "See, all this damage was from a Cat 3" (not directed necessarily at CrazyC83, but some others I've read on this forum). Unfortunately, there aren't many sfc obs along the coast from Bolivar Peninsula to Port Arthur, a stretch of land that should have seen the strongest winds. Again, I'm NOT saying that this wasn't a 100 kt storm. However, if the only real evidence of a particular max wind is a "rule of thumb" FL-to-SFC reduction, when the SFMR and dropsonde data don't support it and hadn't supported the standard reduction factor previously, then I think it's dubious to make such a claim.

For much of its time over the Gulf the FL reduction factor of 90% was indeed too high, but in the hours up until landfall the storm took on a much better and more NORMAL presentation. It's possible that by that time the 90% reduction factor could have been relevant.

Either way, there's plenty of time for the NHC to review all of the available data and make their final conclusion in the post-season report. No reason to rush it.

[gsgs]

I don't know much about hurricanes, but from the pictures
it looked like a rotating ring ("doughnut") with diameter 200km,
ring speed ~180km/h , forward speed ~25km/h ,
so the right halfring would have 205km/h and the left one (Houston) 160km/h.
Then it weakens by 4.6km/h each hour as it goes over land.
That makes it ~25km/h slower in Houston than on landfall.
Well, at that time still half of the ring was over water, so I
estimate 15-20km/h slower in Houston or 140-145km/h
in Houston

?


1 km/h = 0.62mph = 0.54KN

[Lowpressure]

I think we have all learned one thing here. The NHC need to revisit the way they label a storm as far as intensity. There should be more factors involved than just wind speed. Surge should equate in the formula as well as wind field size.

[Matt-hurricanewatcher]

I think we have all learned one thing here. The NHC need to revisit the way they label a storm as far as intensity. There should be more factors involved than just wind speed. Surge should equate in the formula as well as wind field size.

I think there should be 2 of them...

1# the current system for winds...
2# A surge system...

Like

Cat1S 5-7 feet
Cat2S 7-12 feet
Cat3S 12-18 feet
Cat4S 18-22 feet
Cat5s 22+ feet

Kind of like this...

Hurricane Noname is now a cat3 hurricane in the centeral gulf of Mexico with Winds of 120 mph and pressure 955 millibars, also he is graded at a cat4S for his size and wind field.

[gsgs]

but can the (future-) surges be predicted as well as the windspeeds ?
they were pretty bad with Ike.
No special surge-warning until Thursday and then the prediction
was much too high

[gubyw1]

Based on the photos of damage in downtown Houston, it looks like a pocket of 95 kt winds with higher gusts moved through an area there. The office tower windows looked like the thick plexiglass type, and having 90% of the windows out on one side plus some facade ripped off, like in one of the photos I saw of the Chase building shows some intense winds moved through that area. I would say Ike was a cat 3 with 100 kt winds, but only in very small areas, and the IR pics clearly showed Ike strengthened moving over land with a eye presentation improving even as it moved over Houston. In any case, most of the damage was caused by surge, and as bad as it was it would have been MUCH worse if Ike's eye had moved in 15 miles further west. Flooding in Mobile, Slidell and west N.O, Houma, Port Arthur area, Lake Charles, Galveston and Corpus Christi means this storm is going to be very costly, and I think more than the 22 billion insured recently estimated.

[Derek Ortt]

Looking at the data, Ike was not any more intense than 90KT at landfall

where are some of you getting 100KT from? It is most certainly not coming from the data

and no, Houston had nothing even remotely close to 95KT sustained winds. See Lauderdale for what real cat 2 winds do to a major city. Houston did not resemble Lauderdale after Wilma (it was close to Miami)

[gubyw1]

Wilma, Lauderdale:

http://outdoors.webshots.com/photo/1512 ... 2385EeqbDk

Ike, downtown Houston: just as bad, if not worse than Wilma.


http://www.khou.com/perl/common/slidesh ... xtimage=19

[CrazyC83]

Wilma, Lauderdale:

http://outdoors.webshots.com/photo/1512 ... 2385EeqbDk

Ike, downtown Houston: just as bad, if not worse than Wilma.


http://www.khou.com/perl/common/slidesh ... xtimage=19

I figure the winds were about 80 kt sustained in downtown Houston based on that damage.

[DESTRUCTION5]

Looking at the data, Ike was not any more intense than 90KT at landfall

where are some of you getting 100KT from? It is most certainly not coming from the data

and no, Houston had nothing even remotely close to 95KT sustained winds. See Lauderdale for what real cat 2 winds do to a major city. Houston did not resemble Lauderdale after Wilma (it was close to Miami)

U saw that 118Kt wind reported by recon about 6 hrs till landfall..

[Aslkahuna]

Have to remember that winds can be a full category higher 10-20 stories above the 10m height used for surface winds which is what the intensities in the advisories are based upon so we can't use high rise damage as an indicator for surface intensity.

Steve

[wxman57]

Looking at the data, Ike was not any more intense than 90KT at landfall

where are some of you getting 100KT from? It is most certainly not coming from the data

and no, Houston had nothing even remotely close to 95KT sustained winds. See Lauderdale for what real cat 2 winds do to a major city. Houston did not resemble Lauderdale after Wilma (it was close to Miami)

I'd agree, not a Cat 3. Even the 95 kts at landfall may have been generous. Ike just wasn't transporting the higher winds aloft down to the surface. Most of Houston saw only TS conditions in the western eyewall. Fine with me, maybe my power will be back on soon. I'm thankful we didn't go through the eastern eyewall and see the big surge into the Bay and hurricane-force winds.

[Tampa Bay Hurricane]

Based on how Ike was getting better organized and had a deep
intense core near landfall, it might have been a category 3 of
115 mph, but I am no expert. It just looked like a category 3 on
infrared satellites.

But I will agree then with the two professional meteorologists above
because they know much more about hurricanes. I was just going off
of staring at an infrared satellite image.