Close-in Development-Worst Case Scenario ?

[gatorcane]

It's one thing staring down the barrel of a developed Cat 5 that is closing in on you....what would happen if instead 36 hours out, it was just a tropical storm with potential to rapidly intensify? What if Katrina was a tropical storm on Sunday morning instead of a Cat 5? What if Katrina then went through a rapid intensification to a Cat 3 or 4 by landfall in Buras Monday morning? Would people have taken the threat of a 'potential catastrophic hurricane' as seriously as an approaching already-formed Cat 5?

In my opinion, that is the scariest scenario...a storm like the Labor Day hurricane of 1935. Went from a TS to a Cat 5 in 36 hours. The Florida Keys takes time to evacuate - would officials call for a mandatory evacuation for a t.s. that could become a major hurricane by landfall? Probably. Would residents and visitors heed the calls to leave if they turn on the news and see 'just a tropical storm' 36 hours out? Doubtful.

In other words- will a hurricane warning issued on a storm that is still a developing tropical storm with the potential to intensify prior to landfall elicit the same response from officals and citizens as a hurricane warning issued on an already developed Cat 4 or 5?

I agree with you and very well-said. The nightmare scenario is something like the 1935 Labor Day hurricane because of the massive RI potential. So many people would be in the Keys that did not evacuate because they did not think that it would get that strong. Also, the NHC admits it has a long way to go in accurately predicting the intensity of hurricanes so it is possible it would not have thought that system would end up a CAT 5. It would be interesting to see what the NHC products (like the GFDL) would do with a 1935 Labor Day scenario.

As far as Katrina for Florida, that was a HUGE bullet we dodged. Had Katrina had another 24-36 hours over that warm Gulf stream current east of Florida, it could have easily become a strong hurricane, maybe even a low-end major. Katrina was on the verge of going through RI right before it made landfall in Miami-Dade, and even then, it managed to strengthen some over land. Though it did traverse the Everglades which is generally flat, I think it shows had it had more time over water, it would have really bombed.

[AdamFirst]

Humberto with 12 more hours over water hitting Houston would be up there too.

I was talking to a girl from Port Arthur the night of Humberto. It was rapidly intensifying and heading straight for her and she wasn't even aware...she just figured it'd be some rain and wind.


When her power was restored a couple days later she thanked me for basically telling her to hunker down. :p

[brunota2003]

How would people living in the NYC area react if they were placed directly under the gun of a Major Hurricane? Long Island Express, or something worse?

[Ptarmigan]

I remember Humberto in 2007. The storm that became Humberto formed overnight I remember and suddenly became a hurricane. As for Katrina first hitting Florida, I don't think they really dodged a bullet, they just got hit by a smaller caliber bullet. Had Katrina been a major hurricane when it hit Florida that would of been much worse.

[Blown Away]

The scariest "Close-in Development" has to be the Keys Labor Day Hurricane, it went from TS to Cat 5 in about 48 hours and impacted the Keys at peak intensity.

[Downdraft]

If I'm not mistaken Andrew was reclassified a Cat 5 because it intensified just prior to landfall.

[gatorcane]

1935 Labor Day Hurricane:

[micktooth]

I wouldn't call it a worst case, but I remember living in NOLA in 2005...Cindy was supposed to be a strong TS, but as it approached LA, you could easily make out an "eye" on radar, sure enough Cindy was reclassified as a Cat 1 after the fact. This was an intensifying storm and lead me to believe, "every storm is a bad storm when it's over your house!"

[jinftl]

Andrew did intensify from a Cat 4 to Cat 5 as he was about to make landfall. That is something (other than Lebron and the Heat) that should cause some back-of-the-mind anxiety for south floridians - 2 of the 3 landfalling Cat 5s came ashore in South Florida...both were able to intensify up until landfall. So basically, we live just onshore from a high-octane source of intensification for storms up until they hit Duval Street or Collins Ave. Compare that to our friends north of Hatteras, where it is a test of pure speed that will allow a system to maintain itself as it moves over colder and colder water.

My uneducated thinking is that this is possibly due to the Gulf Stream, high SST and TCHP (warm water to a deep depth). the fact that the florida peninsula is narrow and largely swamps and storms can feed from the heat in the Gulf while still east of Florida, and they are not running into the continental landmass of North America (i.e., half of Katrina is over land before she makes landfall on the Gulf, compared to 90 miles or so of her circulation being over swamps, while the rest is over the Gulf of Mexico (west end of circulation) and Gulf Stream (east end of circulation) prior to her Florida landfall.

Intersting factoid, and maybe a source of a bit of comfort to Northern Gulf Coast residents is the following excerpt from the NHC report on Katrina:

"The rapid weakening of Katrina, from its peak intensity of 150 kt to 110 kt during the last 18 h or so leading up to the first Gulf landfall, appears to have been primarily due to internal structural changes, specifically the deterioration of the inner eyewall without the complete formation of a new outer eyewall. However, Katrina remained very large as it weakened, and the extent of tropical storm-force and hurricane-force winds was nearly the same at final landfall on 29 August as it had been late on 28 August. The weakening could have been aided by entrainment of dry air that was seen eroding the deep convection over the western semicircle while Katrina approached the coast. Gradually increasing wind shear, slightly lower ocean temperatures, and (following the first Gulf landfall) interaction with land each could also have played a role. Without extensive investigation, however, it is not possible to assess the relative roles played by these various factors.

The weakening of major hurricanes as they approach the northern Gulf coast has occurred on several occasions in the past when one or more of these factors have been in place. Indeed, an unpublished study by the National Hurricane Center (NHC) reveals that, during the past 20 years, all 11 hurricanes having a central pressure less than 973 mb 12 h before landfall in the northern Gulf of Mexico weakened during these last 12 h."

source (click on Katrina PDF or Word file for report):
http://www.nhc.noaa.gov/2005atlan.shtml

If I'm not mistaken Andrew was reclassified a Cat 5 because it intensified just prior to landfall.

[cheezyWXguy]

It's one thing staring down the barrel of a developed Cat 5 that is closing in on you....what would happen if instead 36 hours out, it was just a tropical storm with potential to rapidly intensify? What if Katrina was a tropical storm on Sunday morning instead of a Cat 5? What if Katrina then went through a rapid intensification to a Cat 3 or 4 by landfall in Buras Monday morning? Would people have taken the threat of a 'potential catastrophic hurricane' as seriously as an approaching already-formed Cat 5?

In my opinion, that is the scariest scenario...a storm like the Labor Day hurricane of 1935. Went from a TS to a Cat 5 in 36 hours. The Florida Keys takes time to evacuate - would officials call for a mandatory evacuation for a t.s. that could become a major hurricane by landfall? Probably. Would residents and visitors heed the calls to leave if they turn on the news and see 'just a tropical storm' 36 hours out? Doubtful.

In other words- will a hurricane warning issued on a storm that is still a developing tropical storm with the potential to intensify prior to landfall elicit the same response from officals and citizens as a hurricane warning issued on an already developed Cat 4 or 5?

I agree with you and very well-said. The nightmare scenario is something like the 1935 Labor Day hurricane because of the massive RI potential. So many people would be in the Keys that did not evacuate because they did not think that it would get that strong. Also, the NHC admits it has a long way to go in accurately predicting the intensity of hurricanes so it is possible it would not have thought that system would end up a CAT 5. It would be interesting to see what the NHC products (like the GFDL) would do with a 1935 Labor Day scenario.

As far as Katrina for Florida, that was a HUGE bullet we dodged. Had Katrina had another 24-36 hours over that warm Gulf stream current east of Florida, it could have easily become a strong hurricane, maybe even a low-end major. Katrina was on the verge of going through RI right before it made landfall in Miami-Dade, and even then, it managed to strengthen some over land. Though it did traverse the Everglades which is generally flat, I think it shows had it had more time over water, it would have really bombed.

Well in terms of Katrina's landfall in florida, i do agree that that area dodged a bullet. However, Katrina's landfall impact along the northern gulf coast, I believe, would have been lessened had it been a weak storm that rapidly intensified until landfall. Katrina's worst damage occurred because of storm surge and flooding, not wind, as is the case with a number of hurricanes, and Katrina would not have been able to produce the massive storm surge it did without being the large, strong, and already well established hurricane it was.