ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM
 
Tropical Storm Iselle Discussion Number  13
NWS National Hurricane Center Miami FL       EP142020
900 AM MDT Sat Aug 29 2020

Iselle has changed little in organization since the last advisory, 
as the storm has a classic shear pattern in satellite imagery with 
the low-level center near the northeastern edge of the convective 
mass.  Satellite intensity estimates have changed little in the 
last 6 h, so the initial intensity remains 40 kt.

The cyclone has tracked a little to the right with the initial 
motion now north-northeastward or 025/6 kt.  This should be 
short lived, and Iselle is expected to resume a northward motion 
later today or tonight.  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 
is tweaked a little from the previous forecast based on the initial 
position and motion.

Iselle is moving over decreasing sea surface temperatures, and it 
continues to experience easterly vertical shear.  This combination 
should cause steady weakening, and the new intensity forecast 
follows the previous forecast in calling for the system 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.  The new intensity forecast lies 
at the upper edge of the intensity guidance.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/1500Z 20.3N 114.7W   40 KT  45 MPH
 12H  30/0000Z 21.3N 114.6W   35 KT  40 MPH
 24H  30/1200Z 22.8N 114.7W   30 KT  35 MPH
 36H  31/0000Z 23.9N 115.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  31/1200Z 24.7N 115.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  01/0000Z 25.4N 116.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  01/1200Z...DISSIPATED
 
$$
Forecaster Beven
 
NNNN