Wednesday, August 29, 2012

Isaac's Slow Dance Along Bayou

Isaac has skirted the Gulf coast overnight, making a couple of landfalls along its way overnight. As of 5 AM this morning, Issac is still skirting the coastline but has now wobbling onshore after having stalled for a time overnight. New Orleans had picked up wind gusts to over 60 mph in seven of eight hours last night as the storm crossed to its south.

There have been some reports of flooding from coastal flooding going over the top of levees along the Mississippi Delta to New Orleans' south.  There will likely be more reports of flooding-related impacts from the storm over the next several hours as it continues to slowly push inland...either from coastal surge or from rain.  The city had picked up 2.94" of rain between Midnight and 5 AM local time, a total of 7.46" with the storm so far...with more to come.

Isaac's slow movement northwest today and then to the north over the succeeding days will result in the potential of inches of rain along its path.  Computer modeling suggests at least a foot of rain will fall in portions of Louisiana (specifically near New Orleans) over the next 36 hours, with the potential for over three inches of rain as far north as Illinois and Indiana by the time we get to Saturday evening.  The National Hurricane Center suggests the possibility of 20 inches of rain before this is done in a few isolated locations.  Coastal flooding due to a strong onshore flow is leading to surge levels of six to ten feet along the Louisiana and Mississippi coastlines this morning, with coastal flooding remaining an issue down there through today as the storm continues to push water onshore.

While Isaac will very likely cause additional flooding problems in Louisiana -- and it may very well be a bad flooding situation before the storm subsides tonight in New Orleans -- the rains will be very welcome for those in the Midwest who are drought-stricken.  The unfortunate reality is that New Orleans is in the midst of a very slow moving storm this morning...and that the rains there aren't needed.

Isaac's winds will slowly subside today -- the rains will continue -- and the storm will get "downgraded" later on back to a tropical storm as it continues to slowly nose into Louisiana.

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