Dry air originally south of tropical storm Isaac has wrapped around to the north side disrupting eye development and thunderstorm activity on the whole north side. Isaac strengthened to about 5 miles per hour short of hurricane but strengthening now appears to have stopped. Isaac may eventually reach hurricane strength, but is now very unlikely to become a highly destructive major hurricane. It doesn't have time to organize much better before it comes ashore with such a large amount of dry air on its north side. Coastal residents still need to take Isaac seriously because it is a large storm moving a large mass of water. Buoy wave heights maxxed out at 17 feet at buoy 42003. That's not very impressive compared to a major hurricane which would hit 40 feet or higher. Isaac is capable of bringing flash floods and tornadoes to inland areas as it comes ashore, but it doesn't appear to be a major threat to New Orleans.
Water vapor imagery shows dry air wrapped near the core of Isaac on the north side.
10pm CDT UPDATE
Isaac has remained just under hurricane strength for hours but the NHC is forecasting the storm to strengthen to a hurricane at the high end of category 1 before it comes ashore. The engineered structures around New Orleans should be strong enough to protect the city. Obviously, it will be dangerous near landfall and all evacuation orders should be followed.
FORECAST POSITIONS AND MAX WINDSAnd NHC says 6 to 12 inches of rain is forecast with as much as 18 inches possible.
INIT 28/0300Z 27.1N 87.0W 60 KT 70 MPH
12H 28/1200Z 28.0N 88.0W 70 KT 80 MPH
24H 29/0000Z 29.1N 89.2W 80 KT 90 MPH...ON THE COAST
36H 29/1200Z 29.9N 90.1W 65 KT 75 MPH...INLAND
48H 30/0000Z 30.7N 90.7W 50 KT 60 MPH...INLAND
72H 31/0000Z 33.3N 91.7W 30 KT 35 MPH...INLAND
96H 01/0000Z 37.5N 91.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 02/0000Z 40.5N 87.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 6 TO 12 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 18 INCHES...IN SOUTHEASTERN LOUISIANA...SOUTHERN MISSISSIPPI... SOUTHERN ALABAMA AND THE EXTREME WESTERN FLORIDA PANHANDLE.
TORNADOES...ISOLATED TORNADOES ARE POSSIBLE ACROSS WEST-CENTRAL AND NORTHWESTERN FLORIDA THROUGH TONIGHT...AND ALONG THE NORTHERN GULF COAST LATE TONIGHT AND TUESDAY.