Potential Tropical Cyclone One Discussion Number   6
NWS National Hurricane Center Miami FL       AL012024
1000 PM CDT Tue Jun 18 2024

Satellite images show little change with the low during the past 
several hours.  Air Force Reserve dropsonde data indicate that the 
strongest winds remain hundreds of miles north of the center, with a 
large area of lighter winds in the circulation center.  While 
there has been some increase in convection near the estimated 
center, the system still doesn't meet the requirements of a tropical 
cyclone.  The official designation of a named storm or not is 
almost academic at this point, with almost all of the significant 
hazards well north of the center.

The system has turned northwestward tonight at about 6 kt.  A 
mid-level ridge over the eastern United States is forecast to build
southwestward, forcing the disturbance to turn westward and
accelerate toward the coast of Mexico overnight and on Wednesday. 
Guidance has trended southward since the last advisory, and the 
official track forecast is nudged that way.

Global models continue to suggest that the circulation will 
gradually consolidate over the next 24 hours, and transition to a 
tropical storm is shown then.  Only modest intensification is
forecast before the center reaches land due to the continued broad
nature of the circulation.  Little change was made to the previous 
wind speed forecast.

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 areas of higher terrain across the Mexican states of Coahuila and
Nuevo Leon, including the city of Monterrey.

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

4. Tropical storm conditions are expected to begin overnight or on
Wednesday 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  19/0300Z 22.5N  93.0W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
12H  19/1200Z 22.7N  94.4W   40 KT  45 MPH...POTENTIAL TROP CYCLONE
24H  20/0000Z 22.8N  96.3W   40 KT  45 MPH...TROPICAL CYCLONE
36H  20/1200Z 22.9N  98.5W   35 KT  40 MPH...INLAND
48H  21/0000Z 23.0N 100.5W   20 KT  25 MPH...INLAND
60H  21/1200Z...DISSIPATED

$$
Forecaster Blake