Strongest June storm?

[CrazyC83]

It seems to match up with alot of GOM Hurricanes who have had their eyewalls eroded by dry air or other factors. Lili, Opal, Ivan, Rita, Frederic, Kate, Andrew (I think). All of those storms were weakening at the point of landfall.

The dry air and cooler SST's seems to be our shield against full fledged category 4 or 5 storms up here along the northern Gulf, but that doesn't stop them from usually bringing in a massive storm surge.

I can't think of any storm that hit the northern Gulf as a Cat 4 or 5 (or a slow-moving Cat 3) and was clearly strengthening. Eloise was the strongest storm I can think of that hit the northern Gulf while strengthening; it was a fast-moving Cat 3, which seems to be the most that the northern Gulf can support while strengthening.

The sides of the Gulf can definitely support strengthening major hurricanes up to landfall - Charley a great example, another I can think of is Celia in 1970 (I think it was about 125 kt at landfall).

[Derek Ortt]

It seems to match up with alot of GOM Hurricanes who have had their eyewalls eroded by dry air or other factors. Lili, Opal, Ivan, Rita, Frederic, Kate, Andrew (I think). All of those storms were weakening at the point of landfall.

The dry air and cooler SST's seems to be our shield against full fledged category 4 or 5 storms up here along the northern Gulf, but that doesn't stop them from usually bringing in a massive storm surge.

Thats because even if they weaken, that surge they already kicked up is already coming, plus storms like Katrina and Ivan were very large Hurricanes.

you're reasoning is wrong.

As Chris and I have said before, a small area of wind 12 hours before landfall contributes next to nothing to the surge. It is the area of gale/storm/hurricane force winds that causes the surge. When these storms weaken, the wind field expands due to angular momentum conservation. Thus, it is possible that the rapidly weakening hurricanes near landfall produce a higher surge than expected as they tend to be larger

[Ed Mahmoud]

People still think Camille was a 5 at landfall, right?

[Dionne]

People still think Camille was a 5 at landfall, right?

NHC/NOAA history records Camille as becoming a cat 5 on August 16, 1969......maintaining intensity with landfall on August 17. Pressure was 26.84 at Bay St Louis. Actual wind speed is unknown as instrumentation failed, although 200 mph is the estimate. 75 miles inland at Columbia, Mississippi they recorded 120 mph winds. It is interesting to note that there were still concrete slabs left from Camille when Katrina hit the same region in 2005.

[Hybridstorm_November2001]

This discussion has me pondering some things. Can anyone explain to me why Northern GOM land falling storms tend to be about the same maximum strength (in terms of sustained winds) cat 3, or low end cat 4, as maximum strength Southern New England/Long Island land falling storms?

http://www.aoml.noaa.gov/hrd/Landsea/12Tides.pdf

Does dry air entrainment and low oceanic heat content play that huge a negative role in the maintenance of TC intensity?

[Ed Mahmoud]

This discussion has me pondering some things. Can anyone explain to me why Northern GOM land falling storms tend to be about the same maximum strength (in terms of sustained winds) cat 3, or low end cat 4, as maximum strength Southern New England/Long Island land falling storms?

http://www.aoml.noaa.gov/hrd/Landsea/12Tides.pdf

Does dry air entrainment and low oceanic heat content play that huge a negative role in the maintenance of TC intensity?

I also think baroclinic factors help New England/New York storms at least partially maintain wind speed despite cold water off the coast. The 1938 storm was supposedly moving near 60 mph at landfall, which minimized time over cold water, and while a strong jet from the South no doubt disrupted the West side of the storm, it might have helped the Eastern side maintain strength.


About low oceanic heat content in the Northern GOMEX, and dry air from Texas/Mexico. I've always suspected, if a storm moves fast enough over 30ºC water, it won't have time to upwell sufficient cold water to cause rapid weakening. Ditto time to entrain dry air. So a Cat 4 or Cat 5 moving in at 20 mph or faster is more dangerous than one moving at 10 mph.


It would seem that the Northern Gulf will support at least Category 2 on its own, as only landfall seemed to stop Humberto from becoming a Cat 2 last year.

[CrazyC83]

This discussion has me pondering some things. Can anyone explain to me why Northern GOM land falling storms tend to be about the same maximum strength (in terms of sustained winds) cat 3, or low end cat 4, as maximum strength Southern New England/Long Island land falling storms?

http://www.aoml.noaa.gov/hrd/Landsea/12Tides.pdf

Does dry air entrainment and low oceanic heat content play that huge a negative role in the maintenance of TC intensity?

I also think baroclinic factors help New England/New York storms at least partially maintain wind speed despite cold water off the coast. The 1938 storm was supposedly moving near 60 mph at landfall, which minimized time over cold water, and while a strong jet from the South no doubt disrupted the West side of the storm, it might have helped the Eastern side maintain strength.


About low oceanic heat content in the Northern GOMEX, and dry air from Texas/Mexico. I've always suspected, if a storm moves fast enough over 30ºC water, it won't have time to upwell sufficient cold water to cause rapid weakening. Ditto time to entrain dry air. So a Cat 4 or Cat 5 moving in at 20 mph or faster is more dangerous than one moving at 10 mph.


It would seem that the Northern Gulf will support at least Category 2 on its own, as only landfall seemed to stop Humberto from becoming a Cat 2 last year.

I think the most the northern Gulf can support while strengthening at landfall is Category 3, although the sides of the Gulf can support a strengthening Cat 5 if the storm is very compact (like Charley if he had more time over water).

Looking at the definite major hurricanes in the northern Gulf since 1950, the only one that seemed to make landfall while strengthening was Eloise. I'm not sure the size of that one (probably small), but it was fast-moving. Elena and Alicia seemed to be holding their intensity up to landfall as well, but might have been weakening a bit. All the others (Audrey, Carla, Hilda, Betsy, Alma, Camille, Carmen, Frederic, Kate, Andrew, Opal, Lili, Ivan, Dennis, Katrina, Rita) were clearly weakening at landfall.

As for the 1938 storm, yes it did make landfall as a solid Cat 3 (I think 110 kt), but it was weakening up to landfall (it was a Cat 5 in the open water).

[Ptarmigan]

I wonder how much rain and how strong the winds were in Houston and Galveston during Audrey? It is unlikely it was a Category 4 hurricane, unless the wind came from strong thunderstorms in the hurricane.

[Ed Mahmoud]

The 1938 storm was apparently a Cat 5 East of Florida (although how they know that, escept by extrapolating back from its New York landfall strength and guessing how much it weakened).


The 1938 storm, at 60 mph, would have had only 5 or 6 hours over water really too cool for it to maintain its strength. Now, over 65 or 70ºF water, the surface may have been more stable, and the mixing of strong winds to the surface may have been reduced. Perhaps the 1938 storm may landfall as an 850 mb Cat 4 or Cat 5, but the ratio of surface winds was reduced by a more stable near surface layer. IIRC, Blue Hill Observatory had a fairly significant wind gust, and while higher than the surrounding Boston area, it isn't all that elevated. Maybe. I still think if the mean steering was strong enough to support a 60 mph forward speed, it was probably getting pretty badly sheared, and its strong winds were from baroclinic as well as tropical processes.

[Hybridstorm_November2001]

Oh BTW Hurricane Audrey of 1957 is in the report too. The section on her, like all others, is rather detailed:

http://www.aoml.noaa.gov/hrd/Landsea/12Tides.pdf

[Ed Mahmoud]

Oh BTW Hurricane Audrey of 1957 is in the report too. The section on her, like all others, is rather detailed:

http://www.aoml.noaa.gov/hrd/Landsea/12Tides.pdf

Derek Ortt discussed that very report and whether Hurricane Audrey was a Cat 4 last summer, and again on page 2 of this thread.


I, myself, based on the obs, say probably a Cat 2. The radar animation posted on page 2 shows the eyewall disintegrating before landfall.

[tolakram]

How long will we continue to focus on storm wind speed alone when it so obviously is only a small part of the picture.

Katrina did extensive damage as it was falling apart.

I hope someday a new strength scale is created that takes all factors into account when labeling a storm a certain category. It seems to me the primary purpose of forecasting and warning about tropical storms is to inform the public of the damage that can be expected. Katrina hit with the power of a cat 5 regardless of what it was measured at.

[Dionne]

How long will we continue to focus on storm wind speed alone when it so obviously is only a small part of the picture.

Katrina did extensive damage as it was falling apart.

I hope someday a new strength scale is created that takes all factors into account when labeling a storm a certain category. It seems to me the primary purpose of forecasting and warning about tropical storms is to inform the public of the damage that can be expected. Katrina hit with the power of a cat 5 regardless of what it was measured at.

For coastal residents this is true. But once your out of the storm surge and inland a few miles it's all about the wind while the storm is in progress. Of course there is always inland flooding with torrential rains. For us Katrina was a 5 hour windstorm that knocked out our entire infrastructure.

[Derek Ortt]

the have already been created. ImpactWeather is currently using one and Dr Mark Powell of HRD is using integrated Kinetic Energy

[KWT]

Yep didn't that show Derek that Katrina put out more energy when it was making landfall then Camille despite the latter system being far stronger at landfall?

[Derek Ortt]

yeah, a lot more energy (though the Powell paper had Camielle at 127KT at landfall based upon an H-WIND analysis... so it was not as much greater in intensity as most believe, only 1 category)

The kinetic energy actually did not decrease at all with Katrina when it was weakening, due to the expansion

[Opal storm]

How long will we continue to focus on storm wind speed alone when it so obviously is only a small part of the picture.

I don't think wind was a small part of the picture in Andrew or Charley, and even in Katrina wind did a lot of damage outside the surge. It all depends on what kind of hurricane it is and where your located. As pointed out, if you live along the coast surge will be your #1 concern but if you're inland you're more concerned about the wind.

[Category 5]

you're reasoning is wrong.

As Chris and I have said before, a small area of wind 12 hours before landfall contributes next to nothing to the surge. It is the area of gale/storm/hurricane force winds that causes the surge. When these storms weaken, the wind field expands due to angular momentum conservation. Thus, it is possible that the rapidly weakening hurricanes near landfall produce a higher surge than expected as they tend to be larger

Ah, thanks for verifying that.