Potential Tropical Cyclone One Discussion Number   7
NWS National Hurricane Center Miami FL       AL012024
400 AM CDT Wed Jun 19 2024

Dropsonde observations from an Air Force Reserve Unit Hurricane 
Hunter aircraft indicate that the circulation of the system is 
gradually becoming better defined.  However, the central convection 
remains rather meager and the system's cloud pattern is still not 
classifiable via the Dvorak technique.  Therefore the disturbance 
still does not meet the requirements of a tropical cyclone and will 
continue to be designated as a potential tropical cyclone at this 
time.  Nonetheless, since the system appears to be on its way to 
developing a well-defined center, it is expected to become a 
tropical cyclone later today.  This also suggested by simulated 
satellite imagery from the ECMWF and GFS models that depict 
increasing and organized deep convection near the center as it 
nears the coastline.

The system is turning westward and the current motion is around 
285/7 kt.  A mid-level ridge extending west-southwestward from a 
strong high over the eastern United States should force the 
disturbance to move on a westward path with increasing forward 
speed.  The track model guidance and model consensus are in good 
agreement on this scenario, and the official forecast is 
similar to the previous NHC track, albeit a bit faster.

The current intensity estimate remains at 35 kt based on 
non-elevated surface observations over the Gulf.  Environmental 
conditions, such as warm SSTs and low vertical shear, appear to 
favor some intensification before landfall.  However, the inner 
circulation is likely to remain somewhat broad, limiting 
strengthening.  The official intensity forecast is the same as the 
previous one and in good agreement with the statistical-dynamical 
Decay-SHIPS guidance.

Regardless of the exact track of the low, this system will have a 
large area of heavy rains, moderate coastal flooding and 
tropical-storm-force winds well north of the center.  Importantly, 
the official wind speed probabilities are likely underestimating the 
chances of tropical-storm-force winds along the Texas coast because 
of the unusually large and asymmetric area of strong winds on the 
northern side of the circulation.


Key Messages:

1. Users are reminded not to focus on the exact forecast track of
this system.  The disturbance is very large with rainfall, coastal
flooding, and wind impacts likely to occur far from the center
along the coasts of Texas and northeastern Mexico.

2. Rainfall associated with Potential Tropical Cyclone One will 
impact large regions of Central America, north across northeastern 
Mexico and into South Texas. This rainfall will likely produce 
considerable flash and urban flooding along with new and renewed 
river flooding. Life-threatening flooding and mudslides are likely 
in and near areas of higher terrain across the Mexican states of 
Coahuila, Nuevo Leon, and Tamaulipas, including the cities of 
Monterrey and Ciudad Victoria.

3. Moderate coastal flooding is likely along much of the Texas
Coast through midweek.

4. Tropical storm conditions are expected today along portions of 
the Texas coast south of San Luis Pass and along portions of the 
coast of northeastern Mexico within the Tropical Storm Warning area.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 22.7N  93.8W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
12H  19/1800Z 22.7N  95.0W   40 KT  45 MPH...TROPICAL CYCLONE
24H  20/0600Z 22.7N  97.2W   40 KT  45 MPH...TROPICAL CYCLONE
36H  20/1800Z 22.7N 100.0W   25 KT  30 MPH...INLAND
48H  21/0600Z...DISSIPATED

$$
Forecaster Pasch