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Category 3 to Category 5 on the morning of August 28. Accurately forecasting the timing and magnitude of such extreme hurricanes remains an operational challenge.
Fijjurc 7. NHC 72 hour hurricanc forecast issued at 11 p.m. EDT August 26 56 hours prior to Katrina’s landfall in southeast Louisiana. The cone of uncertainty is represented by the white shading.
According to Louisiana emcrgcncy management, it takes 48 to 72 hours to evacuatc vulnerable residents from New Orleans. NHC’s forecasts afforded emergency management and the public 56 hours to implement their hurricane plans and make evacuation decisions along the north central Gulf Coast.
One of the challenges TPC/NHC encountered during Katrina was projecting the path of the storm across South Florida and the Florida Keys (Figure 8). Katrina moved southwest as it passed over the southern Florida peninsula, south of original forecast track but within historic 10-year average track errors. The more southerly track resulted in tropical storm-force and hurricanc-force winds in the lower Florida Keys and a three to five foot storm surge in portions of Monroe County. There was adequate watch and warning time for the Florida Keys, but a watch was not posted for the Dry Tortugas. TPC/NHC issued a tropical storm warning for the Diy Tortugas at 1 a.m. EDT, August 26, but no hurricane warning was issued. An observation platform there reported tropical storm force winds for about 26 hours beginning about 11 a.m. EDT on August 26, and hurricane force winds were reported for one hour during that period.
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