Isaac Forecast Track Shifts Westward for US Landfall

Dominican Republic, Haiti, and Cuba to Feel Effects Over the Next 72 Hours

Model tracks for Isaac from 00Z model runs the evening of August 23rd.

Models are coming into agreement that Isaac will make a US landfall somewhere in the northeastern Gulf of Mexico during the first part of next week.  The European model was the first to hint at this earlier in the week, but it was the outlier at the time.  Now, all but one of the 20 model runs contained in the image above have Isaac passing over the Gulf of Mexico at some point.  For perspective, consider that multiple “expert” meteorologists were forecasting Isaac to head up the East Coast of Florida as recently as Wednesday (8/22).

Of course, they may still turn out to be right, as the NHC is still having a difficult time finding the exact center of Isaac.  Also, there will be new data from the NOAA G-IV added to tomorrow morning’s model runs that may alter the track again.  The G-IV investigated the area north and northwest or Isaac to gain a better understanding of the dynamics of the upper level of the atmosphere.  This will help improve confidence in the forecast track of Isaac.  If tomorrow morning’s model tracks look similar to the ones above, we can feel more confident about a Gulf Coast landfall somewhere between Apalachicola, FL and New Orleans, LA.  (At which time, we’ll need to start thinking more seriously about New Orleans as a target.)

Isaac will, at the very least, bring heavy rain to Hispaniola and Cuba over the weekend.  This is of great concern for Haiti, who still has over 400,000 people still living in tent camps following the 2010 earthquake.  They could see rainfall totals of 10+ inches of rain in some parts of the country, which could lead to mudslides and flash flooding.

Meanwhile, Joyce was downgraded to a tropical depression and is expected to remain in that state for the next 48-72 hours.  If necessary, we’ll return to Joyce late in the weekend when it may pose a threat to Bermuda as a tropical storm.  Two out of the last three storms (Helene and Joyce) have managed to keep their tropical storm status for less than 36 hours before being downgraded to a depression.  And Isaac has barely maintained tropical storm status as a large, but unorganized low pressure system.

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