Several indications point toward Isaac being at hurricane strength this afternoon. The pressure has steadily fallen and is now estimated to be lower than 982 mb. Surface winds are starting to respond and are estimated at over 70 mph. The satellite appearance is one of a low end hurricane with good banding, outflow and a developing organized central core.
There is a chance that the Hurricane Center will still hold the intensity at tropical storm strength on the next advisory, but it is very close.
Isaac is about 320 miles south southeast of Mobile, Alabama and moving to the northwest at 12 mph.
So where do we go from here? Well, it looks like the slow but steady intensification process has started as the storm continues to look better and better organized, and recon data confirms that. Latest intensity guidance suggests that the system will reach winds of near 100 mph at landfall – which will be in about 36 hours. This is also carried by the National Hurricane Center.
Track guidance remains problematic with the most likely area of landfall just to the west of the mouth of the Mississippi River. There is a wide range in guidance with outliers extending from the Texas/Louisiana border to Mobile, Alabama. This results in the following watches and warnings:
A hurricane warning is in effect from east of Morgan City, Louisiana to the Alabama/Florida border. This warning includes Metropolitan New Orleans… Lake Pontchartrain… and Lake Maurepas.
A hurricane watch is in effect from Intracoastal City to Morgan City, Louisiana.
In the warning area… preparations to protect life and property should be rushed to completion. People in the watch area should seriously consider preparations based on their local area.
On either side of the hurricane watch or warning… there are likely to be tropical storm conditions. Tornado producing rain bands are still affecting Florida, and there will be tornado producing rain bands well inland either side of where Isaac makes landfall.
Longer term guidance has slowed in its western movement. The possibility of the system making it all the way into Oklahoma at about 96 hours is becoming more and more unlikely with a path through Arkansas more likely. There will be a chance of flooding rains and tornadoes associated with the decaying system all the way up to I-40 during the next few days.
In addition to the previously mentioned threats… the National Hurricane Center offers:
Storm surge… the combination of a storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters. The water could reach the following depths above ground if the peak surge occurs at the time of high tide…
- Southeast Louisiana and Mississippi… 6 to 12 ft
- Alabama… 6 to 9 ft
- South-central Louisiana… 3 to 6 ft
- Florida Panhandle… 3 to 6 ft
- Florida west coast including Apalachee Bay 1 to 3 ft
The deepest water will occur along the immediate coast in areas of onshore flow. Surge-related flooding depends on the relative timing of the surge and tidal cycle…and can vary greatly over short distances. For information specific to your area…please see products issued by your local weather service office. Near the coast… the surge will be accompanied by large and dangerous waves.
Rainfall…Isaac is expected to produce additional rain accumulations of 1 to 3 inches over the eastern Florida Peninsula…with isolated storm max totals of 15 to 20 inches possible. Total rainfall amounts of 6 to 12 inches… with max amounts of 18 inches are possible in southeast Louisiana… southern Mississippi…southern Alabama and the extreme western Florida Panhandle.