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Tropical Storm Mario Discussion Number  16
NWS National Hurricane Center Miami FL       EP132025
Issued by the NWS Weather Prediction Center College Park MD
800 AM PDT Tue Sep 16 2025
 
Convection associated with Mario continues to diminish this morning 
as the system moves into cooler waters and encounters increasing 
southwesterly shear. Satellite intensity estimates from TAFB and SAB 
are decreasing, and thus the initial intensity was lowered to 40 kt 
this advisory.

The initial location of Mario remains a bit uncertain, although a 
recent microwave pass from shortly after 09Z indicated the system 
is likely farther southwest than anticipated. As Mario continues to 
weaken and lose vertical structure, the expectation is that the 
shallow low-level circulation will slow down and feel less of an 
impact from the deep-layer southerly flow. This should result in 
an increasingly sheared system, with the low-level circulation 
staying farther west and the mid-level remnants going northward. 
Given this, the latest track forecast is slightly west of the 
previous forecast, generally remaining on the western side of the 
track guidance.

Mario will continue to weaken as it moves over cooler waters and 
increasing shear. As the low-level and mid-level circulation 
decouple, the system will lose its organized convection and should 
become a post-tropical remnant low as soon as tonight. Thereafter, 
the low should dissipate into a trough by 48-60 h. 

While Mario is forecast to dissipate as a tropical cyclone well to 
the south of California, its remnant moisture will spread farther 
north, affecting portions of the southwestern United States by mid 
to late week. Locally heavy rainfall and some instances of flash 
flooding will be possible by Thursday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/1500Z 22.7N 117.2W   40 KT  45 MPH
 12H  17/0000Z 23.7N 118.2W   30 KT  35 MPH
 24H  17/1200Z 24.9N 119.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  18/0000Z 25.8N 120.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  18/1200Z 26.0N 120.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  19/0000Z...DISSIPATED
 
$$
Forecaster Chenard/Blake
 
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