Advisories

000
WTPZ45 KNHC 091447
TCDEP5
 
Hurricane Simon Discussion Number   9
NWS National Hurricane Center Miami FL       EP202026
900 AM CST Fri Oct 09 2026
 
The intensity of Simon has been hard to diagnose this morning. The 
most recent TAFB Dvorak fix still supported an intensity of 80 kt 
at 1200 UTC, while all of the objective techniques from UW-CIMSS 
are lower. Since that time, a warm spot near the center of Simon's 
small CDO has recently appeared, which appears to be the early 
development of an eye. Based on the continued improvement in Simon's 
satellite appearance, the initial intensity has been increased to 85 
kt for the advisory.
 
Over the next 24 hours, continued rapid intensification is expected. 
The RI probabilistic guidance (both SHIPS and DTOPS) actually 
decreased this cycle, but the hurricane is located in a low-shear, 
high-moisture, and high-SST environment that is conducive for 
explosive deepening. Furthermore, recent microwave imagery, such as 
an AMSR3 pass just after 08Z suggests the hurricane has a small 
inner-core, which makes rapid changes in intensity more likely. 
Therefore, the NHC forecast is in line with the previous one, above 
most of the guidance and shows Simon becoming a major hurricane 
later today.
 
Simon's forecast beyond that is extremely difficult, and this is a 
case where it is important to not focus on the details of NHC's 
deterministic forecast. Simon will turn northward this weekend, 
steered between a deep trough to its northwest and a ridge to the 
east. This track will take the center of Simon very near or over the 
Mexican states of Colima and Jalisco. If the center of Simon moves 
over land, it will quickly weaken and could even dissipate, 
drastically lessening the risk of hurricane-force-winds farther 
north in Mexico. However, if the core of Simon remains offshore, it 
will likely continue northward as a hurricane. A majority of the 
guidance this morning shows Simon remaining just offshore, however 
most of these models have historically had a west bias in this 
region. Likewise, ensemble means like GDM or even HCCA can be 
misleading when some members move inland and dissipate. This 
results in the mean being computed solely from the surviving, and 
in this case farther west, members. The NHC forecast therefore 
remains within, but on the east side of the guidance envelope, and 
is best characterized as a hedge between the aforementioned 
possibilities. 
 
 
Key Messages:
 
1. Simon is expected to approach the west-central coast of Mexico
as a major hurricane on Saturday.

2. Catastrophic wind and life-threatening storm surge impacts are 
likely along a portion of the west-central coast of Mexico, and a 
Hurricane warning is in effect from Punta San Telmo to Punta Mita. 
Preparations to protect life and property should be completed by 
late today.

3. Heavy rainfall associated with Simon will impact portions of 
southwestern Mexico through this weekend. This rainfall may produce 
life-threatening flooding and mudslides, especially in areas of 
steep terrain.

4. Swells will affect portions of the southwestern and west-central
coast of Mexico through the weekend. These swells are likely to
cause life-threatening surf and rip current conditions. Please
consult products from your local weather office.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/1500Z 16.0N 104.7W   85 KT 100 MPH
 12H  10/0000Z 16.5N 104.8W  105 KT 120 MPH
 24H  10/1200Z 17.2N 104.9W  125 KT 145 MPH
 36H  11/0000Z 18.2N 105.0W  125 KT 145 MPH
 48H  11/1200Z 19.4N 105.2W  115 KT 130 MPH
 60H  12/0000Z 20.7N 105.4W   95 KT 110 MPH...INLAND
 72H  12/1200Z 21.9N 105.6W   75 KT  85 MPH...OVER WATER
 96H  13/1200Z 23.6N 106.2W   55 KT  65 MPH...INLAND
120H  14/1200Z 24.9N 106.9W   30 KT  35 MPH...POST-TROP/INLAND
 
$$
Forecaster D. Zelinsky