Damage to NO from powerful hurricane comparable to Asian t

[Derek Ortt]

even that small amount of land significantly weakens a hurricane.

In Andrew, for the most part, except for its initial trek over Homestead, it tracked across swamp land, and it still lost 35 or more KT of winds speed (see the BAMS article which indicated that Andrew may have been more intense than the official 145KT, including the H-wind indicating 153KT). That swamp land would still likely weaken the hurricane at least 2 categories (unless it was moving at Opals speed, then 1 category) before hitting the center of the city.

Now, does this help with the tidal surge, well that is a different question, but it highrise evacuation may be an option for a cane hitting from the south, not so from the east since major hurricane sustained winds also would hit the city and highrise evacuation would be as foolish as staying at ground level in the city

[MGC]

A major hurricane approaching NO from the east would not encounter much marsh land at alll before landfall. Erosion has really opened the eastern flank of New Orleans. No way a cane weakens much at all IMO due to lack of warm water or land friction. The salt water marshes of SE Louisiana are nothing like the glades. I've been through both and 10 miles of marsh won't stop a hurricane at all. The only hope would be some situation like happened to Opal, Lili and Ivan with dry continental air along with shear to weaken the hurricane. Given good upper air conditions conditions and no dry air entrainment, a hurricane would intensify to the coast just like Andrew did. Look how long Hurricane Juan was able to maintain its intensity while over land in La in 1985..............MGC

[vbhoutex]

The surge of an Ivan type hurricane would be far higher than the surge observed in Pensacola since the water would have nowhere to flow away down the coast.

The surge at the top of P'cola Bay was some 18 feet if I remember correctly. Basically the same situation will occur with Lake Ponchatrain-no escape route so it piles up. Out on P'cola Beach where the surge could spread it only reached about 10 feet at its' highest I think.

[Derek Ortt]

the 10 miles from the east would not do much, as I said on the posts. That is why I am most concerned about a strike from the east.

It is from the south where the threat to the city is overstated, IMO because then it is 60 miles of swamp, not just 10. That 10 miles may only reduce the winds by 5-10KT