Parameters for Rapid Intensification of Tropical Cyclones

[Stormsfury]

Sounds easy? ... Not at all ...
I received an email from Todd Spindler from the NHC regarding this very subject and that's the reply I received ...

Trying to simplify things wasn't at all easy as well ...

Anyway, the link I received from Todd was a great and a must read.

Factors affecting intensity
http://www.nrlmry.navy.mil/~chu/chap6/se500.htm

Basically to try to simplify things somewhat ... are as such

- A sufficient layer of warm SST's usually deeper than 50 m (usually 26ºC or higher. Rapid deepening is more likely with SST's in excess of 28.5ºC)
- Very Low Vertical wind shear
- Structure of a TC, the better structured, the better the opportunity
- Outflow channels (means to evacuate the air mass from the TC)
- Low-level convergence/circulations

Full Chapter regarding Tropical Cyclone Intensity
http://www.nrlmry.navy.mil/~chu/chap6/se000.htm

[cycloneye]

Interesting reading about this important subject thanks for sharing it with the storm2k members.

[isobar]

Thanks for posting the link, SF, and thanks especially for taking the time to put it into simpler terms for some of us who are novices.

[Lindaloo]

Thanks for posting the link, SF, and thanks especially for taking the time to put it into simpler terms for some of us who are novices.

DITTO THAT!!! Thanks Mike.

[Stormsfury]

Bump.

[wx247]

Thanks for bumping this topic Storms. I might have missed it you hadn't done that!

Informative. When I get just a little time I am going to make sure I read it all. I have bookmarked the links. Thanks again!

[JetMaxx]

Here's a vivid example of what happens when all five parameters come together and rapid deepening occurs.....this is a visible satellite image of hurricane Camille over the southeastern GOM at 1:10 p.m. est on August 16, 1969. At the time of this image, maximum sustained winds were IMHO 180 mph (155 kts) and a hurricane hunter aircraft had just reported a central pressure of 908 mb/ 26.81"
http://www1.ncdc.noaa.gov/pub/data/imag ... amille.gif

PW

[Lindaloo]

Thanks Perry!! I have never seen a pic of her.

[JetMaxx]

There aren't many Lindaloo.....Camille occurred in the days when we only had visible satellite images (why there's no satellite photos available of Camille at landfall along the Mississippi Coast at 10 p.m. CST).

Infrared (IR) nighttime satellite technology didn't become available until 1975....I still remember the first hurricane I ever saw on IR satellite....Eloise approaching the Florida panhandle on 9/23/75.

Camille was the most awesome hurricane I've ever seen...because of how rapidly she deepened -- from a strong tropical wave to cat-3 in 21 hours; from tropical wave to cat-5 in less than 48-- even Gilbert didn't bomb into a monster that fast.

[Stephanie]

That photo of her is awesome! Perfectly shaped and scarey as h*ll!!! :o

[Rainband]

Thanks SF..great info..and thanks Perry for the image of that monster..I don't like saying her name..scary what "she" would do in the GOM today :o

[Amanzi]

Thanks for the links and the info SF

OMGoodness.... Perry, thank you for that pic, that is one very beautiful but exceedingly scary lady.. I am amazed at the short time it took her to become a cat 5... in less than 48hrs!!!!!! That is just amazing and truly scary!...

John I dont even want to imagine what would happen if something span up that quickly into something that huge in this day and age of prime GOM property!!! A truly scary thought indeed :o

[JetMaxx]

That's a hurricane forecaster's worst nightmare Johnathan...a hurricane of that extreme intensity slamming into a highly populated coastal metro area such as Galveston-Houston, Miami-Fort Lauderdale, New Orleans, or Tampa Bay.

As bad as Andrew was for south Florida, a "Camille-like" cat-5 would be much worse....storm tides would be 19-20' instead of 16-17'; and Camille was about twice the size of Andrew....meaning a 50 mile wide swath of total destruction instead of 25-30.

If hurricane Andrew had been the size and intensity (180-185 mph) of Camille...IMHO downtown Miami would have been obliterated, and might not be fully recovered even today.

**An interesting sidenote: We don't know with certainty just how intense Camille was. Without IR satellite, and with only three eye penetrations by reconnisance aircraft between Western Cuba and Mississippi, it's almost a certainty that Camille's central pressure was lower than 905 mb.

We had NOAA and USAF recon in Allen, Gilbert, and Mitch almost constantly while they were at cat-5 status. Not so in hurricane Camille....and we know from Gilbert that pressure fluctuations of several millibars occurred within hours. I almost bet Camille's pressure dipped to or below 900 mb -- at least briefly.

Also, the 909 mb/ 26.85" reading at Bay St Louis, Mississippi is considered Camille's "official" landfall central pressure -- but Camille brushed against the Mouth of the Mississippi (SE Louisiana) several hours earlier...and there was no recon inside the hurricane. Due to mechanical problems, the aircraft was forced to leave the area and make an emergency landing at Houston. I'm almost certain Camille's central pressure was lower near Burrwood than at Bay St Louis, likely by several millibars (based on other hurricanes I've observed on a similar track).

[Lindaloo]

It would be devastating again for the MS Gulf Coast if another Camille were to blow this way again. You should see how much this coast has grown from Biloxi to Pass Christian. Nothing but casinos and hotels now. They are right on the water too.

[JetMaxx]

We are very fortunate that hurricanes like Camille don't make landfall very often at peak intensity...only three cat-5's making landfall in the U.S. since 1900 (and IMO Andrew was borderline cat 4/5).

Most hurricanes that reach that extreme intensity weaken some before landfall (Hugo, Mitch, Allen); but when they do strike land at 160+ mph, usually it's catastrophic.

Here are the only confirmed landfalling cat-5's in the Western Hemisphere since 1900:

1) Labor Day hurricane (Fla Keys 1935) 892 mb/ 200+ mph

2) Camille 909 mb/ 180 mph

3) Gilbert (Yucatan) 900 mb/ 170-175 mph

4) Janet (Yucatan/Belize 1955) 914 mb/ 175 mph

5) Santiago, Cuba (1932) 915 mb/ 160+ mph

6) Andrew 922 mb/ 160-165 mph

Several others were borderline cat 4/5 at landfall....such as 1961's Hattie in Belize, 1979's David in Dominican Repubic, 1977's Anita in NE Mexico, 1966's Inez in Hispanola; and a 1919 hurricane that obliterated the Florida Keys.

PW

[Guest]

Or to think if a Hurricane like Gilbert hit us too. I don't know folks but I'm afraid I am going to see this is my lifetime in the USA.

Patricia

[JetMaxx]

Ticka...it won't take a hurricane like Gilbert. Four years ago, if hurricane Floyd doesn't take a hard right turn to the north....we would have witnessed the hurricane disaster of the century.

I shudder to think what a hurricane the size of Floyd would have done to the Florida Peninsula with 155 mph sustained winds and a core that large....a stronger version of hurricane Carla. If Floyd had made landfall near Fort Lauderdale and recurved across Florida toward Orlando and Jacksonville, IMO hundreds would have died, and the property damage would have exceeded 100 billion dollars.

We've dodged giant bullets like that for decades as coastal areas have exploded in population....and it's just a matter of time. The Galveston Disaster, Great Miami Hurricane, and Long Island Express weren't just freaks that will never occur again -- we've just been lucky (Hugo and Andrew both missed the bullseye...and in Andrew's case, only because the intense core was so small).