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Tropical Storm Iselle Discussion Number  14
NWS National Hurricane Center Miami FL       EP142020
300 PM MDT Sat Aug 29 2020

Iselle has become less organized during the past several hours, as 
the area of convection southwest of the center is now smaller and 
farther from the center than previously.  This is likely due to the 
combined effects of continued easterly shear and decreasing sea 
surface temperatures under the storm.  A recent ASCAT overpass 
shows that maximum sustained winds remain near 40 kt, but the 
tropical-storm-force winds are now occurring only over the 
southeastern quadrant.

The initial motion is north-northeastward or 025/6 kt.  Iselle 
should turn toward the north during the next several hours as it 
is steered by a mid-level ridge to the east.  The northward motion 
should continue for another day or so, followed by a turn toward 
the northwest as Iselle becomes a weak and shallow system.  The new 
forecast track again has minor adjustment from the previous track 
based mainly on the initial position and motion.

The shear and cooler water along the forecast track should cause 
Iselle to steadily weaken, and the new forecast track has no 
changes from the previous forecast.  The forecast, which calls for 
the cyclone to weaken to a depression by 24 h, to degenerate to a 
remnant low by 36 h, and to weaken to a trough by 72 h, again lies 
at the upper edge of the intensity guidance.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/2100Z 21.0N 114.5W   40 KT  45 MPH
 12H  30/0600Z 22.1N 114.5W   35 KT  40 MPH
 24H  30/1800Z 23.4N 114.8W   30 KT  35 MPH
 36H  31/0600Z 24.2N 115.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  31/1800Z 24.8N 115.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  01/0600Z 25.4N 116.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  01/1800Z...DISSIPATED
 
$$
Forecaster Beven
 
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