Tropical Cyclone Discussion

351
WTPZ45 KNHC 132036
TCDEP5
 
Tropical Depression Fifteen-E Discussion Number   1
NWS National Hurricane Center Miami FL       EP152026
200 PM PDT Sun Sep 13 2026

Deep convection became more persistent overnight and this 
morning in association with the area of low pressure (EP97) located 
southwest of the southern tip of the Baja Peninsula.  The system is 
being affected by moderate west-northwesterly shear, and the center 
has recently become exposed to the northwest of the area of deep 
convection.  Regardless of the exposed center, subjective Dvorak 
T-numbers increased to T1.5 at 18z with data T-numbers slightly 
higher.  Therefore, advisories are being initiated on a 30-kt 
tropical depression. 

The environment ahead of the depression is not expected to be 
conducive for significant strengthening.  However, most of the 
intensity guidance calls for the system to reach tropical storm 
strength within the next day or so.  By 48 hours, continued 
moderate shear and drier mid-level air are expected to cause gradual 
weakening.  Simulated satellite imagery from the GFS and ECMWF show 
the deep convection waning in 3 to 4 days and the system is likely 
to become a remnant low during that time.  The global models 
indicate that the system will become an open trough before the
end of the 5-day forecast period, and the official forecast follows 
suit. 

The depression is moving generally westward or 260/7 kt.  A 
mid-level ridge to the north and northwest of the system is expected 
to steer it south of due west during the next few days.  The 
guidance suggests the forward speed will increase, especially 
toward the end of the period when the cyclone weakens and becomes 
even more vertically shallow.  The NHC forecast follows the faster 
solutions of the typically reliable GDM and HCCA consensus aids. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/2100Z 17.2N 117.2W   30 KT  35 MPH
 12H  14/0600Z 17.0N 118.2W   35 KT  40 MPH
 24H  14/1800Z 16.7N 119.8W   35 KT  40 MPH
 36H  15/0600Z 16.5N 121.6W   35 KT  40 MPH
 48H  15/1800Z 16.4N 123.6W   30 KT  35 MPH
 60H  16/0600Z 16.3N 125.7W   30 KT  35 MPH
 72H  16/1800Z 16.1N 128.1W   30 KT  35 MPH
 96H  17/1800Z 16.0N 133.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  18/1800Z...DISSIPATED