Tropical Cyclone Discussion

666
WTPZ43 KNHC 132048
TCDEP3
 
Tropical Storm Hernan Discussion Number   4
NWS National Hurricane Center Miami FL       EP082026
200 PM PDT Thu Aug 13 2026
 
Hernan continues to be affected by strong westerly wind shear today. 
After a brief increase in convection this morning, showers and 
thunderstorms have become displaced to the northeast and east, 
leaving the center of circulation almost completely exposed. An 
earlier scatterometer pass indicated that the storm had moved nearly 
due south from the previous center position and that the radius of 
34 kt winds has contracted. Recent subjective and objective 
intensity estimates, however, range from 28-45 kt. Keeping all of 
this in mind, the initial intensity is maintained at 40 kt for this 
advisory.
 
The storm is moving southward at around 5 kt along the southeastern 
periphery of a ridge building to the northwest. A gradual turn 
toward the southwest and then west-southwest is forecast from Friday 
into this weekend as Tropical Storm Lala strengthens to the west. 
The latest NHC forecast has been shifted slightly to the left of the 
previous advisory during the first 24 h and sped up somewhat beyond 
24 h through the remainder of the forecast period. Considerable 
spread persists among the track guidance, so confidence in the 
track forecast remains below average.
 
Although Hernan remains over warm 27-28 C waters and within a fairly 
moist mid-level environment, strong westerly  shear is expected to 
support gradual weakening tonight. By early Friday, increasingly dry 
mid-level air and decreasing upper-level divergence should further 
inhibit the storm's organization. The ECMWF and GFS simulated 
satellite imagery suggest that Hernan may struggle to maintain 
organized convection on Friday, and the latest forecast calls for 
the system to degenerate to a remnant low by 36 h. The post-tropical 
low is expected to gradually spin down, open into a trough, and 
dissipate in a few days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/2100Z 17.3N 131.9W   40 KT  45 MPH
 12H  14/0600Z 16.8N 132.0W   35 KT  40 MPH
 24H  14/1800Z 16.2N 132.4W   30 KT  35 MPH
 36H  15/0600Z 15.9N 133.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  15/1800Z 15.4N 135.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  16/0600Z 15.0N 136.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  16/1800Z...DISSIPATED