Isaac make landfall overnight for a second time near Grand Isle, LA and has spent most of the day over or near Houma, LA. At least I got the general location of landfall correct! Storm surge flooding has been a significant issue south and east of New Orleans, but so far it appears the city has done ok. Isaac is going to continue its painfully slow motion to the northwest over the next 24 hours. Isaac has been downgraded to a 70 mph tropical storm as the storm has spent much of today over the bayous which don’t create enough friction to fully weaken the system. Areas from Lafayette to Lake Charles should continue to see conditions deteriorate this evening with showers and gusty winds. Rainfall amounts will taper off as one goes west and the next phase of this storm will be heavy rain in northern LA and southern AR.
The 18z or 2 pm model track guidance shows a slow motion towards northwest LA in the next 24 hours with a gradual increase in forward speed heading into Friday. This will provide some very beneficial, heavy rainfall for parched areas of the Mid-Mississippi Valley where Summer rainfall deficits are over 6″-8″.
Of course, looking at the rainfall graphic above, it might be too much of a good thing in most areas. The St. Louis area is forecast to receive over 8″ of rain in a short amount of time. This heavy rainfall will most likely continue east over the weekend possibly arriving in the Mid-Atlantic by early next week.
As part of my job as a satellite expert for a few NOAA National Weather Service National Centers, I get to view some incredible satellite imagery. I put together a loop of Hurricane Isaac from yesterday showing the storm approaching southeast LA. Click on the image below to animate it. I’m sure you will be as mesmerized as I am!