Hurricane Isaac Forecast Discussion

000
WTNT45 KNHC 282042
TCDAT5

Hurricane Isaac Discussion Number  12
NWS National Hurricane Center Miami FL       AL102024
900 PM GMT Sat Sep 28 2024

The expected weakening of Isaac appears to have started.  The eye of 
the hurricane has been filling some during the past few hours, and 
the convective pattern is losing symmetry with dry air entraining 
into the southwestern side of the circulation.  The Dvorak 
classifications are dropping, and accordingly, the initial intensity 
is nudged downward to 85 kt.  The hurricane is already over cool 24 
C waters and it is headed for progressively cooler waters during the 
next several days.  These unfavorable oceanic conditions coupled 
with a sharp increase in vertical wind shear should cause steady 
weakening, and a transition into a post-tropical cyclone in about 
36 hours.

Isaac is moving relatively quickly northeastward at 16 kt.  The 
system is forecast to move a little slower to the east-northeast or 
northeast during the next couple of days within the mid-latitude 
flow.  After that, a turn to the north is expected on the eastern 
side of an extratropical low.  No significant changes were made to 
the previous track forecast, and this one lies fairly close to the 
various consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 41.3N  38.4W   85 KT 100 MPH
 12H  29/0600Z 42.5N  37.0W   75 KT  85 MPH
 24H  29/1800Z 43.7N  35.1W   65 KT  75 MPH
 36H  30/0600Z 44.8N  32.3W   55 KT  65 MPH...POST-TROPICAL
 48H  30/1800Z 46.1N  30.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 60H  01/0600Z 48.3N  28.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
 72H  01/1800Z 50.4N  27.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  02/1800Z 54.0N  26.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  03/1800Z 56.9N  23.6W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Cangialosi