Tropical Cyclone Discussion

343
WTPZ45 KNHC 150839
TCDEP5
 
Tropical Storm Simon Discussion Number  32
NWS National Hurricane Center Miami FL       EP202026
200 AM MST Thu Oct 15 2026
 
The satellite presentation of Simon has not changed much since the 
prior advisory. The center of the tropical storm remains embedded 
underneath a small, cold central dense overcast. No recent passive 
microwave data is available to assess the internal structure of 
Simon, but conventional satellite images indicate it is still a 
small storm. The initial intensity is lowered slightly to 50 kt. 
This is based on a blend of the TAFB Dvorak estimate (T3.5/55 kt) 
and the latest UW-CIMSS objective estimates (43-52 kt), with some 
consideration given to the earlier aircraft data as well.

Simon has been nearly stationary for the past few hours, but its 
longer-term motion has been a southwestward drift. The storm is 
likely to meander within very weak steering currents during the next 
12-24 h. By Friday, the track models generally agree that Simon will 
turn northwestward on the east side of a cutoff low near the 
southwestern United States. This should bring the center of the 
compact tropical cyclone near but to the west of Baja California 
over the weekend. Based on the latest track guidance, the NHC 
forecast has been shifted slightly left of the previous prediction, 
in the direction of HCCA and closer to the TVCN simple consensus.

Little change in strength is expected today while Simon meanders 
over warm waters and vertical wind shear over the storm gradually 
strengthens. Much stronger southwesterly shear is forecast on Friday 
and into the weekend, which should disrupt the vertical structure of 
the storm and introduce drier air into its circulation. The NHC 
forecast has once again trended weaker, following the latest 
multi-model consensus aids. Simon is predicted to lose organized 
convection and become post-tropical by 72 h. It would not be 
surprising if this occurs even sooner, as some models like the ECMWF 
and Google DeepMind show Simon dissipating late this weekend. Given 
the latest track forecast trends and the small size of Simon, wind 
watches are not needed for Baja California Sur at this time.
 
 
Key Messages:
 
1. Interests in Baja California Sur should continue to closely 
monitor the latest updates as Simon is expected to pass near or west 
of that area this weekend.
 
2. Large swells will likely affect portions of the coast of 
west-central Mexico and Baja California Sur over the next couple of 
days. These swells could cause life-threatening surf and rip current 
conditions.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  15/0900Z 19.2N 108.5W   50 KT  60 MPH
 12H  15/1800Z 19.1N 108.5W   50 KT  60 MPH
 24H  16/0600Z 19.6N 108.9W   45 KT  50 MPH
 36H  16/1800Z 20.5N 109.8W   40 KT  45 MPH
 48H  17/0600Z 21.3N 110.9W   35 KT  40 MPH
 60H  17/1800Z 22.2N 112.0W   30 KT  35 MPH
 72H  18/0600Z 23.2N 113.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  19/0600Z 26.0N 114.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  20/0600Z...DISSIPATED