Founder of the Weather Channel, Bryan Norcross, on how soon to be Hurricane Isaac is huge and slow moving, and that ain’t good.
Taken together, the NHC’s Cat. 2 forecast looks reasonable, though preparations should be made for a Cat. 3, given the lack of skill inherent in intensity forecasting.
In any case, that same large circulation will move a lot more water toward the coast than an average hurricane. The entire Hurricane Warning area – from Louisiana to the western Panhandle – is extremely vulnerable to storm surge flooding. The NHC is forecasting 6 to 12 feet of water ABOVE THE GROUND in spots along that stretch of coast.
Normally, the exact amount of surge will be dependent on the exact track and where in the tide cycle the storm comes in. In Isaac’s case, however, there will be such a long duration of onshore winds, due to the storm’s size and slow forward speed, the water may stay high for more than one tide cycle.
In fact, that size and slow forward speed will make this a hurricane experience like none in memory, if it comes together as forecast.
Unless something unexpected happens, it’s truly a nightmare scenario.