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Tropical Storm Nicholas Discussion Number   1
NWS National Hurricane Center Miami FL       AL142021
1000 AM CDT Sun Sep 12 2021
 
Showers and thunderstorms associated with a broad area of low 
pressure over the southern Bay of Campeche have increased overnight 
and very recently become better organized with a loose band of 
convection around the northeastern portion of the circulation. An 
Air Force Reserve reconnaissance aircraft that has been 
investigating the system has found 44-kt flight-level winds and 
SFMR winds that support a 35-kt initial intensity.  Based on the 
recent increase in organization and the 35-kt initial intensity, 
advisories are being initiated on Tropical Storm Nicholas, the 
fourteenth named storm of the Atlantic hurricane season. 

The storm is located within an environment of moderate 
south-southwesterly vertical wind shear, over warm waters, and in a 
moist and unstable atmosphere. These conditions should allow gradual 
strengthening over the next 24 to 48 hours.  The NHC intensity 
forecast follows suit and calls for gradual strengthening until 
the system reaches the coast of Texas.  The official wind speed 
forecast is near the higher end of the guidance in best agreement 
with the SHIPS statistical guidance, the HFIP corrected consensus, 
and the HWRF.  In this case, the intensity forecast is highly 
dependent on eventual track of the system.  A track to the east of 
the NHC forecast could result in a lower wind shear environment 
and slightly more time over water for the system to strengthen.  
Conversely a track to the west of the forecast track would result 
in the system interacting with land much sooner. 

Since the system is still in its formative stage the initial motion 
estimate is a somewhat uncertain 330/11 kt.  A north-northwestward 
motion around the western portion of a mid-level ridge that is 
sliding east near the coast of the Carolinas, should continue to 
steer Nicholas in that direction for the next 24 to 48 hours.  
After that time, steering currents weaken and the cyclone is 
expected to move slowly north-northeastward between a couple of 
mid-level ridges located to the east and west of Nicholas.  The 
track guidance generally agrees with this overall scenario but 
there is some cross-track spread with the UKMET along the left side 
of the guidance envelope taking the storm into northeastern Mexico, 
while the GFS, HWRF, and HMON are along the right side.  The NHC 
track is near the various consensus models and both the EC and GFS 
ensemble means.

Key Messages:

1. Tropical storm conditions are expected along portions of the 
northeastern coast of Mexico and the coast of south Texas 
beginning on Monday.  Nicholas is forecast to approach the middle 
Texas coast as a strong tropical storm on Tuesday, and tropical 
storm conditions are possible along portions of the middle and upper 
Texas coasts late Monday night and Tuesday. 

2. There is the possibility of life-threatening storm surge along 
the coast of Texas from the Mouth of the Rio Grande to High Island. 
Residents in these areas should follow any advice given by local 
officials. 

3.  Periods of heavy rainfall are expected to impact portions of the 
Texas and Louisiana coasts today through the middle of the week. 
Significant rainfall amounts are possible, potentially resulting in 
areas of flash, urban, and isolated river flooding.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/1500Z 20.5N  94.8W   35 KT  40 MPH
 12H  13/0000Z 21.9N  95.7W   40 KT  45 MPH
 24H  13/1200Z 24.1N  96.6W   45 KT  50 MPH
 36H  14/0000Z 26.4N  96.9W   50 KT  60 MPH
 48H  14/1200Z 28.2N  96.5W   55 KT  65 MPH
 60H  15/0000Z 29.4N  95.9W   40 KT  45 MPH...INLAND
 72H  15/1200Z 30.3N  95.2W   30 KT  35 MPH...INLAND
 96H  16/1200Z 31.0N  94.8W   25 KT  30 MPH...INLAND
120H  17/1200Z 32.0N  94.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Brown
 
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