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Isaac 12-24 hours from Landfall in Louisiana

   Posted by Levi at 3:28pm on August 28, 2012

Isaac remains a tropical storm per the NHC, despite a dropsonde observation of 70kt winds at the surface (hurricane force is 64kt), and 85kt flight-level winds in the NE eyewall. It is unclear why they have chosen not to upgrade Isaac, but he will be a hurricane at landfall, and strengthening. Isaac has continued to gradually deepen during the last 48 hour period at a fairly consistent pace, but dry air remains integrated with his circulation, making the eyewall ragged. This is what has prevented Isaac from becoming a major hurricane. The storm will be strengthening through landfall though, and Isaac will likely have upper-end Cat 1 winds coming to the surface at landfall due to turbulent mixing.

The biggest problem with Isaac will probably not be the wind but the extreme rainfall of 12-18 inches forecasted in the New Orleans and southern Mississippi area during the next 48 hours. This will cause flooding problems, along with a higher storm surge than one would typically expect from a Cat 1 hurricane due to its slow movement. Hopefully residents are not taking this storm lightly, as it will be a quite nasty one as it comes ashore in 12-24 hours, depending on exactly which point on the Mississippi Delta it crosses the coastline. Tropical storm force rain bands are already moving onshore. I will be posting short updates on Facebook throughout the day on Isaac.

We shall see what happens!


6 comments

   

Comments

  • Gary Z says:

    Finally a Hurricane..never has so much been made over a 5mph upgrade…..

  • Jeff H. says:

    http://www.aoml.noaa.gov/phod/cyclone/data/go.html

    Levi, can’t help but think that the low level of TCHP has saved the NOLA folks from another Katrina. Though we haven’t seen what the storm surge is going to do as yet.

  • Anonymous says:

    Why is the GFS still bringing the storm into Texas after making landfall? Levi, do you think this has a chance of happening?

  • Jason says:

    My question is the same as above (15:21) Why does the GDS continue to show this it dosen’t make any since. This storm hasn’t made any since. Anyways Levi can you please respond to my question. It GFS continues to ride the costline west to Texas and it looks it keeps it strong as well.

  • Levi says:

    Steering currents are very weak so Isaac’s movement is slow and erratic. While it could get somewhat farther west, it’s not going to the Texas coastline, though some rain could spread into far eastern Texas after landfall.

  • Jeff H. says:

    Levi,

    I am a Meteorology 101 guy without advanced knowledge. Could you elaborate as to the circumstances that kept Isaac from reaching above Cat 1. I mentioned TCHP above which I gathered from my readings but would be interested in your brief synopsis or bullet points if it would not take too much time or typing.

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