Tropical Storm Nicholas Advisory Number 2
NWS National Hurricane Center Miami FL AL142021
400 PM CDT Sun Sep 12 2021
...NICHOLAS EXPECTED TO STRENGTHEN AS IT MOVES TOWARD THE NORTHWEST
...STORM SURGE WARNING AND HURRICANE WATCH ISSUED FOR A PORTION OF
THE TEXAS COAST...
SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
ABOUT 160 MI...260 KM ESE OF LA PESCA MEXICO
ABOUT 240 MI...385 KM SSE OF MOUTH OF THE RIO GRANDE
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NNW OR 340 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning has been extended eastward to Freeport,
A Storm Surge Warning has been issued for the coast of Texas from
Port Aransas to San Luis Pass, including Aransas Bay, San Antonio
Bay, and Matagorda Bay.
A Hurricane Watch has been issued for the coast of Texas from Port
Aransas to Sargent.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Port Aransas to San Luis Pass Texas
* Aransas Bay, San Antonio Bay, and Matagorda Bay
A Hurricane Watch is in effect for...
* Port Aransas to Sargent Texas
A Tropical Storm Warning is in effect for...
* Mouth of the Rio Grande to Freeport Texas
* Barra el Mezquital to the U.S./Mexico border
A Storm Surge Watch is in effect for...
* Mouth of the Rio Grande to High Island Texas
A Tropical Storm Watch is in effect for...
* North of Port Aransas to High Island Texas
A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
during the next 36 hours in the indicated locations. For a
depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
hurricanes.gov. This is a life-threatening situation. Persons
located within these areas should take all necessary actions to
protect life and property from rising water and the potential for
other dangerous conditions. Promptly follow evacuation and other
instructions from local officials.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
A Storm Surge Watch means there is a possibility of life-threatening
inundation, from rising water moving inland from the coastline, in
the indicated locations during the next 48 hours. For a depiction of
areas at risk, please see the National Weather Service Storm Surge
Watch/Warning Graphic, available at hurricanes.gov.
A Hurricane Watch means that hurricane conditions are possible
within the watch area. A watch is typically issued 48 hours before
the anticipated first occurrence of tropical-storm-force winds,
conditions that make outside preparations difficult or dangerous.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.
Interests elsewhere along the upper Texas coast should monitor the
progress of this system.
For storm information specific to your area in the United
States, including possible inland watches and warnings, please
monitor products issued by your local National Weather Service
forecast office. For storm information specific to your area
outside of the United States, please monitor products issued by
your national meteorological service.
DISCUSSION AND OUTLOOK
At 400 PM CDT (2100 UTC), the center of Tropical Storm Nicholas was
located near latitude 22.8 North, longitude 95.5 West. Nicholas is
moving toward the north-northwest near 14 mph (22 km/h), and this
general motion is expected through tonight. A slower northward or
north-northeastward motion is forecast by late Monday or Monday
night. On the forecast track, the center of Nicholas will pass near
or just offshore the coasts of northeastern Mexico and South Texas
on Monday, and move onshore along the coast of south or central
Texas coast Monday night or early Tuesday.
Maximum sustained winds are near 40 mph (65 km/h) with higher gusts.
Strengthening is forecast until Nicholas reaches the northwest Gulf
coast Monday night or early Tuesday.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center.
The estimated minimum central pressure is 1008 mb (29.77 inches).
HAZARDS AFFECTING LAND
Key messages for Nicholas can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC
and on the web at hurricanes.gov/graphics_at4.shtml?key_messages
RAINFALL: Nicholas is expected to produce storm total rainfall of
8 to 16 inches, with isolated maximum amounts of 20 inches, across
portions of the middle and upper Texas coastal areas today through
the middle of the week. Across the rest of coastal Texas into
southwest Louisiana rainfall of 5 to 10 inches is expected. This
rainfall may produce areas of considerable flash and urban flooding,
especially in highly urbanized metropolitan areas. Additionally,
there is the potential for isolated minor to moderate river
Over the northeastern portions of the Mexican state of Tamaulipas
rainfall amounts of 2 to 5 inches can be expected today into Monday.
STORM SURGE: The combination of a dangerous storm surge and the tide
will cause normally dry areas near the coast to be flooded by rising
waters moving inland from the shoreline. The water could reach the
following heights above ground somewhere in the indicated areas if
the peak surge occurs at the time of high tide...
Port O'Connor to San Luis Pass TX including Matagorda Bay...3-5 ft
Mouth of the Rio Grande to Port O'Connor, TX...2-4 ft
San Luis Pass to High Island, TX including Galveston Bay...2-4ft
Baffin Bay, Corpus Christi Bay, Aransas Bay and San Antonio
High Island, TX to Intracoastal City including Sabine Lake and
Calcasieu Lake..1-3 ft
The deepest water will occur along the immediate coast in areas
of onshore flow, where the surge will be accompanied by large and
dangerous waves. Surge-related flooding depends on the relative
timing of the surge and the tidal cycle, and can vary greatly over
short distances. For information specific to your area, please see
products issued by your local National Weather Service forecast
WIND: Tropical storm conditions are expected to first reach the
coast within the warning area in northeastern Mexico and southern
Texas Monday morning, making outside preparations difficult or
dangerous. These conditions will spread northward within the
warning area through Monday night. Hurricane conditions are
possible in the Hurricane Watch area Monday night. Tropical storm
conditions are possible within the watch area by late Monday night
or early Tuesday.
TORNADOES: A tornado or two will be possible Monday into Monday
night across the middle and lower Texas coast.
SURF: Swells generated by Nicholas will begin affecting
portions of the northwest Gulf coast later tonight and continue
into Tuesday. These swells are likely to cause life-threatening
surf and rip current conditions. Please consult products from your
local weather office.
Next intermediate advisory at 700 PM CDT.
Next complete advisory at 1000 PM CDT.
Tropical Storm Nicholas Discussion Number 2
NWS National Hurricane Center Miami FL AL142021
400 PM CDT Sun Sep 12 2021
Visible satellite imagery, scatterometer wind data, and earlier
reconnaissance aircraft observations indicate that the circulation
of Nicholas is elongated from northwest to southeast. In fact,
visible satellite imagery and the aircraft data has shown that
there have been several low-level swirls rotating about a mean
center. This is not surprising since the tropical cyclone is
still in its formative stage. The Air Force plane did not find
winds any stronger than they did this morning and the ASCAT data
revealed peaks winds of around 30 kt. Given the typical
undersampling of the scatterometer instrument, the earlier aircraft
data, and peak one-minute wind observations of 31 kt from NOAA buoy
42055 earlier today, the intensity remains 35 kt for this advisory.
Nicholas will be moving over the warm waters of the western Gulf of
Mexico during the next day or so, and this combined with a moist,
unstable atmosphere favors strengthening. The primarily inhibiting
factor appears to be moderate south-southwesterly vertical wind
shear caused by an upper-level trough over northern Mexico. The
trough is forecast to move westward and weaken during the next day
or so, which could allow for a more favorable upper-level wind
pattern later tonight and Monday. The NHC intensity forecast again
calls for strengthening while the system moves toward the northwest
Gulf coast, but the main uncertainty regarding the intensity
forecast is how much time the cyclone will spend over the Gulf
waters. The GFS and HWRF models, which depict a track farther
east, show significantly more strengthening than the UKMET and ECMWF
models which show a weaker tropical cyclone moving inland over
northeastern Mexico or southern Texas much sooner. The NHC intensity
forecast is similar to the previous advisory, but indicates a faster
rate of strengthening during the next 12-24 hours. Although not
explicitly shown in the intensity forecast, Nicholas could approach
hurricane strength when it nears the northwest Gulf coast,
especially if it moves to the right of the NHC forecast track and
spends more time over water. Due to this uncertainty a Hurricane
Watch has been issued a for a portion of the Texas coast. The NHC
forecast is in best agreement with the SHIPS and HFIP corrected
consensus model, but is not as high as the latest HWRF.
The center of Nicholas appears to have re-formed farther north since
this morning and the initial motion estimate is again a somewhat
uncertain 340/12 kt. The track forecast reasoning has not changed
from this morning. Nicholas should move north-northwestward to
northward during the next day or so around the western portion of a
mid-level ridge that is located near the southeast U.S. coast. The
latest runs of the various dynamical models have shown typical
variability, but the overall guidance envelope has not changed too
much through the first 36 hours. The GFS has been the most
consistent model and its 12Z run was fairly close to the previous
NHC track forecast. Therefore, the NHC track leans along the right
side of the guidance envelope between the HWRF and GFS, which
are a little to the right of the consensus aids. Due to the acute
angle of approach of Nicholas to the coast, users are reminded to
not focus on the exact forecast track as small changes in the
heading of the cyclone could result in differences in both the
location and timing of landfall. Regardless of where Nicholas makes
landfall, storm surge, wind, and rainfall impacts are likely over a
large portion of northeastern Mexico and Texas coastal areas.
After landfall, a slower north-northeastward motion is forecast, and
by 72 hours the cyclone is forecast to be located between a couple
of mid-level ridges, which will likely result in weaker
steering currents and an even slower northeastward motion. By day
5, the global model guidance suggest that the low-level circulation
will become an open trough so dissipation is indicated at that time.
1. 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 considerable flash and urban flooding, especially in highly
urbanized metropolitan areas. Isolated minor to moderate river
flooding is also expected.
2. There is the danger of life-threatening storm surge inundation
along the coast of Texas from Port Aransas to San Luis Pass.
Residents in these areas should follow any advice given by
3. Nicholas is forecast to approach the middle Texas coast as a
strong tropical storm late Monday and early Tuesday, and could be
near hurricane intensity if it moves to the right of the forecast
track and remains over water longer. Tropical storm conditions are
expected along portions of the middle Texas coast beginning Monday
afternoon, with hurricane conditions possible from Port Aransas to
Sargent late Monday and Monday night.
4. Tropical storm conditions are expected along portions of the
northeastern coast of Mexico and the coast of south Texas beginning
FORECAST POSITIONS AND MAX WINDS
INIT 12/2100Z 22.8N 95.5W 35 KT 40 MPH
12H 13/0600Z 24.4N 96.3W 45 KT 50 MPH
24H 13/1800Z 26.7N 96.9W 55 KT 65 MPH
36H 14/0600Z 28.7N 96.8W 55 KT 65 MPH...INLAND
48H 14/1800Z 30.4N 96.3W 35 KT 40 MPH...INLAND
60H 15/0600Z 31.2N 95.8W 30 KT 35 MPH...INLAND
72H 15/1800Z 31.7N 95.2W 25 KT 30 MPH...INLAND
96H 16/1800Z 31.9N 94.7W 20 KT 25 MPH...POST-TROP/REMNT LOW