Hurricane Isaac Discussion Number  10
NWS National Hurricane Center Miami FL       AL102024
900 AM GMT Sat Sep 28 2024

Isaac has continued to strengthen this morning.  The satellite
presentation consists of a 20 nm (WMG 8C) clear eye and an
impressive curve band in the north side of the cyclone beneath the
upper diffluent westerlies.  The initial intensity is bumped up to
90 kt for this advisory and is based on a UW-CIMSS SATCON  analysis
of 93 kt and the Dvorak intensity estimates for TAFB and SAB.

Some fluctuations in strength are possible during the day, after 
which Isaac will be traversing cooler oceanic surface temperatures 
and experiencing increasing deep-layer shear.  Subsequently, 
gradual weakening is forecast, and the cyclone is expected to lose 
its deep core convection and become a post-tropical cyclone in 48 
hrs.  After that time, the global model fields and the FSU Cyclone 
Phase Evolution forecast show Isaac transitioning from a symmetric 
warm-core system to an asymmetric cold-core, more frontal thermal 
structure.  The NHC intensity forecast is similar to the consensus 
aids and shows Isaac completing its extratropical cyclone 
transition by Tuesday.

Isaac has turned toward the northeast, or 055/17 kt, in response
to a mid-latitude shortwave ridge temporarily building to the north 
of the cyclone.  By early next week, as Isaac loses its tropical
characteristics and completes an extratropical transition, the
cyclone should turn toward the north-northeast while a major 
shortwave trough approaches from the northwest over the central 
Atlantic.  The official track forecast is adjusted a little to the 
right of the previous forecast beyond 48 hrs to agree more with 
the TVCA and HCCA consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT  28/0900Z 39.3N  41.3W   90 KT 105 MPH
12H  28/1800Z 40.4N  39.2W   85 KT 100 MPH
24H  29/0600Z 42.1N  37.0W   75 KT  85 MPH
36H  29/1800Z 43.5N  35.2W   65 KT  75 MPH
48H  30/0600Z 44.6N  33.1W   55 KT  65 MPH...POST-TROPICAL
60H  30/1800Z 46.0N  31.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
72H  01/0600Z 48.0N  30.4W   45 KT  50 MPH...POST-TROP/EXTRATROP
96H  02/0600Z 52.5N  30.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  03/0600Z 55.7N  28.6W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Roberts