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Potential Tropical Cyclone Sixteen-E Discussion Number   3
NWS National Hurricane Center Miami FL       EP162023
1000 AM CDT Sun Oct 08 2023
 
The system appears to be getting slowly better organized this 
morning, though it remains unclear if a well-defined center has 
formed. An SSMIS pass at 1110 UTC revealed a decent curved 
convective band to the northwest of the best low-level turning, but 
there is a lack of clear evidence of a tighter low-level circulation 
on the low-level 37 GHz channel. First-light visible images on the 
1-minute GOES-18 meso-sector also remain unclear on the circulation 
definition. Thus, the system remains a potential tropical cyclone, 
but given the improvement in banding the initial intensity was 
raised to 30 kt, a bit higher than the TAFB and SAB Dvorak 
estimates.
 
First-light visible imagery suggests the best position of the system 
right now is just a little north and west of overnight estimate, 
resulting in a slow northwest motion at 320/4 kt. The overall track 
reasoning remains unchanged, as the system is expected to move 
north-northwestward or northward over the next 24-36 h, in between a 
mid-level ridge centered to its east over the northwest Caribbean, 
and Tropical Storm Lidia located to its west. This motion should 
bring the system inland over Mexico just beyond 36 h from now. 
However, notable differences in the timing of landfall between the 
guidance remain. The GFS model, in addition to the 
hurricane-regional models based on the GFS initial conditions  
(HWRF, HMON, HAFS-A/B) continue to be much faster than other global 
model guidance such as the ECMWF and CMC. This disagreement is 
likely at least partially related to the fact the disturbance does 
not yet have a well-defined center, and may potentially form further 
north closer to land. For now, the NHC track forecast leans towards 
the slower solutions, but has shifted a bit east compared to the 
previous track, and is a little slower than the consensus aid TVCE.
 
Given the gradually improving structure, the system is expected to 
become a tropical cyclone soon, and most of the intensity guidance 
suggest continued intensification up till landfall. The NHC 
intensity forecast continues to show a peak intensity of 45 kt near 
landfall, which is on the high end of the intensity guidance that 
appears biased by the GFS and its hurricane-regional models that 
bring the system inland faster than shown here. It is notable that 
the ECMWF and CMC show a stronger tropical cyclone than the NHC 
forecast, mainly because they spend a longer period of time 
offshore.
 
Based on the latest forecast showing the system near landfall in   
36 h, the government of Mexico has upgraded the area previously 
under a Tropical Storm Watch to a Warning.
 
Key Messages:
 
1. The disturbance is expected to become a tropical storm before it
approaches the coast of southern Mexico on Monday.  A tropical storm
warning is now in effect for a portion of the coast of southern
Mexico.
 
2. Heavy rains from this system will likely produce flash and urban
flooding, along with possible mudslides in areas of higher terrain
across the states of Guerrero, Michoacan and coastal sections of
western Oaxaca.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/1500Z 15.0N 101.1W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  09/0000Z 15.5N 101.2W   35 KT  40 MPH...TROPICAL CYCLONE
 24H  09/1200Z 16.2N 101.3W   40 KT  45 MPH
 36H  10/0000Z 17.1N 101.4W   45 KT  50 MPH
 48H  10/1200Z 18.0N 101.1W   30 KT  35 MPH...INLAND
 60H  11/0000Z...DISSIPATED
 
$$
Forecaster Papin
 
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