Cat 4 hurricanes very unlikely north of Florida on E Coast

[Scorpion]

Hugo's winds were 135mph at landfall.

Best track is 120 kts, and that is based off old FL-wind deductions.

[storms in NC]

Well I am sorry but I have to Disagree with you. I think a cat 4 or 5 can come up the east coast from Ga. to NC with no trouble. Yes it has to be just right for it to happen but it can happen and I think it will happen. It is just the matter of time. The waters here are getting wamer than they use too, and that is a big factor in if a cat 4 or 5 to come up the east coast.

[MiamiensisWx]

Disagree. If it had weakened all the way to a Cat 1 or 2 instead of borderline Cat-4, there would have been a much smaller surge. It would have made a HUGE difference, IMO, as the wind field, while still large, would have been weaker.

I'm willing to challenge that. Katrina's large windfield and early very intense peak intensity allowed the large surge to build up, so even if it weakened to a Category One or Category Two, geography, the setup, and the large windfield - along with the earlier very intense 175MPH sustained winds/902 millibars peak - would have still allowed a tremendous surge very similar - possibly only a bit less - than what actually occurred.

NOTE - I am NOT trying to trivalize what actually occurred.

[Derek Ortt]

a 100 year return period, plus the fact that the Gulfstream is about 60 miles offshore, meaning you have an NGOM-like situation where you have very shallow warm waters, means any 4's or 5's that are not flying likely will weaken before landfall. Cat 4's just are not likely for the EC

The cat 3 return time is much higher than the cat 4 time

[Noles2006]

Disagree. If it had weakened all the way to a Cat 1 or 2 instead of borderline Cat-4, there would have been a much smaller surge. It would have made a HUGE difference, IMO, as the wind field, while still large, would have been weaker.

I'm willing to challenge that. Katrina's large windfield and early very intense peak intensity allowed the large surge to build up, so even if it weakened to a Category One or Category Two, geography, the setup, and the large windfield - along with the earlier very intense 175MPH sustained winds/902 millibars peak - would have still allowed a tremendous surge very similar - possibly only a bit less - than what actually occurred.

NOTE - I am NOT trying to trivalize what actually occurred.

If Katrina would have experienced a much more dramatic pressure increase and wind decrease, the surge would have undoubtedly been much less.

[MiamiensisWx]

If Katrina would have experienced a much more dramatic pressure increase and wind decrease, the surge would have undoubtedly been much less.

Possibly, but probably not as much as you think, unless it was an EXTREMELY rapid drop in the maximum sustained winds and rise in pressure accompanied by a decrease in the windfield (e.g., Opal in 1995), THEN the surge might have had a more significant decrease, but likely only in this type of scenario; otherwise, I see little decrease in surge amounts, even if Katrina weakened down to a Category One/Category Two before landfall.

What evidence are you basing your statement on? Just curious.

[Hybridstorm_November2001]

Cat 4 can happen, but like the study said, are very unlikely. About the only possible cat 4 that ever made landfall in SE New England for example was the Great Hurricane of 1635, it was at least a cat 3 of that there is little doubt. However due to the age of the storm it is almost impossible to declare it a cat 4 with 100% certainty. That said, if it was such, it was very likely the only one in New England at least, to occur in roughly 400 years.

[Matt-hurricanewatcher]

Truthfully Katrina was a cat5 less then 8 hours before landfall. I don't think even if she would of droped to a tropical storm, that the surge would of been less then 25 feet. It was amazing how fast she weaken...I had a friend on Aim say that the goverment cut the storm in half.

[Audrey2Katrina]

There is absolutely no way Hugo could have been a 5 at S. Carolina landfall by every indication I've reviewed or by NOAA's own reconnaisance records, or what little land measurements exist. Top sustained 1 min. winds in Charleston (close to the landfall area) were about 87 mph top gust reached 135--and the min. pressure at this landfall was 934-937... just WAY to high to be a Cat 5 hurricane IMO. Make no bones about it, Hugo was a horrible storm, and the worst was still a few miles more to the north of Charleston. I have a personal friend lives about 20 mi. from the landfall--rode it out, and before Andrew it was the all-time most expensive in damage--but it wasn't remotely a 5 at landfall--with all due respect to those who feel otherwise.

A2K

[Audrey2Katrina]

I had a friend on Aim say that the goverment cut the storm in half.

Could you explain how the government could've achieved this?

A2K

[Matt-hurricanewatcher]

I believe that strong upper level shear when the storm got picked up, sheared the southwestern side. In which made it look like it. Surge would not of went down alot...Ivan was a cat5 over the southern gulf in still had near cat5 surge by the time it made landfall. So if you get a cat5 over the gulf watch out.

[gatorcane]

I agree with Derek - in fact I will even go as far as saying only the FL peninsula below 30N could support a CAT 4. South Florida is the prime area for a CAT 4+ to hit. Once you get north of about 30N which includes all of the northern GOM and NE Florida and points north, it is very difficult.

The main reasons are:

1) oceanic heat content not high enough (e.g. the Gulf stream only hugs the FL east coast from about Jupiter south)
2) North of about 30N the chances of westerly shear increase
3) As strong hurricanes like Katrina near the northern GOM, they suck in alot of dry air from the mainland. It is the reason for a sudden weakening below CAT 4 strength with nearly every CAT 4+ heading towards the northern GOM).

[Extremeweatherguy]

We do not have a reliable long enough data set to make such assumptions.


BTW There is evidence that points towards Hugo being a cat 5 at SC landfall, but nothing has been decided definitively on reanalysis yet. Same goes for Hazel being a cat 4, rather than 3, at landfall.

yeah you and derek have been hinting at that for months. Curiousity peaked now...wanna know more

I have a question...if Hugo was a Cat. 5 at landfall, then where is the proof? I have never seen a single wind damage picture or video that has showed anything nearly to Cat. 5 levels from Hugo. In fact, it is even hard for me to believe Hugo was a 4! Now of course if someone can post some facts to back up this possibility I may change my tune, but for now I would have to say Hugo was nowhere near Cat. 5 levels.

[Extremeweatherguy]

There is absolutely no way Hugo could have been a 5 at S. Carolina landfall by every indication I've reviewed or by NOAA's own reconnaisance records, or what little land measurements exist. Top sustained 1 min. winds in Charleston (close to the landfall area) were about 87 mph top gust reached 135--and the min. pressure at this landfall was 934-937... just WAY to high to be a Cat 5 hurricane IMO. Make no bones about it, Hugo was a horrible storm, and the worst was still a few miles more to the north of Charleston. I have a personal friend lives about 20 mi. from the landfall--rode it out, and before Andrew it was the all-time most expensive in damage--but it wasn't remotely a 5 at landfall--with all due respect to those who feel otherwise.

A2K

I agree 100%. Well said A2K.

[mountainspring]

OK, everyone (and especially Derek!), what's your opinion on the likelihood of a Cat 4 or 5 hitting Tampa?

[gatorcane]

OK, everyone (and especially Derek!), what's your opinion on the likelihood of a Cat 4 or 5 hitting Tampa?

Well Tampa is borderline area for a CAT 4+ to hit. I think north of Tampa is unlikely but south of Tampa is very possible.

So I think Tampa has a chance but the strongest they ever had was a CAT 3 at the end of October way back in 1921....

[Hybridstorm_November2001]

All I know is that if cat 3s can hit New England, than a cat 4 can hit the Carolinas. It only makes sense.

[wxman57]

Disagree. If it had weakened all the way to a Cat 1 or 2 instead of borderline Cat-4, there would have been a much smaller surge. It would have made a HUGE difference, IMO, as the wind field, while still large, would have been weaker.

I'm willing to challenge that. Katrina's large windfield and early very intense peak intensity allowed the large surge to build up, so even if it weakened to a Category One or Category Two, geography, the setup, and the large windfield - along with the earlier very intense 175MPH sustained winds/902 millibars peak - would have still allowed a tremendous surge very similar - possibly only a bit less - than what actually occurred.

NOTE - I am NOT trying to trivalize what actually occurred.

Actually, CapeVerdeWave, it was demonstrated by a storm surge expert at the National Hurricane Conference that the fact that Katrina was a Cat 5 offshore had very little to do with the eventual storm surge - perhaps only a few feet. What was much more significant was the radius of Katrina's max winds at landfall (and their average speed). So how high Hugo's surge would have been at landfall as a Cat 1 or 2 would depend more on the expanse of those Cat 1 or 2 winds than on Hugo's wind field well offshore as a Cat 4.

[Matt-hurricanewatcher]

I don't think so a cat1 would not do the same level of surge as a cat5. Why because of strong winds moving over the surface of the ocean. In which the winds moving the waves are alot slowlier/weaker for the cat1 then the cat5..Which builds waves height like any storm. The more winds moving across the ocean the higher the waves will be(Storm waves). Also the deeper the pressure the large the mound/surge will form under the center of the cane.

A cat1 will not bring nearly as high of a surge as a cat5. In fact if you get a cat5 over the gulf unlike winds water works alot slower. So its likely to stay that way for 12 to 24 hours if not more after weaking.

So if you have a cat5 8 hours before landfall. The winds will go down but the water will not. Yes the size of the area of winds are importand, and can increase the level of storm surge. But the fact is katrina was a cat5.

[Derek Ortt]

Charleston was in the SW half, where the speed of motion was against the wind. Therefore, since the motion was about 25 m.p.h., the winds in the nrothern eye wall should be about 50 m.p.h. stronger than Charleston received (CHARLESTON EXPERIENCED A CAT 1/2 HURRICANE, NOT A 4)

As for Hugo being a 5, the NHC report indicated that at landfall, flight level winds were 141KT, and this flight level was at 12,000 feet, where a 95-100% reduction factor is used