Potential Tropical Advisory. Advisory #5

WTNT33 KNHC 182032
TCPAT3

BULLETIN
Potential Tropical Cyclone Three Advisory Number   5
NWS National Hurricane Center Miami FL       AL032021
400 PM CDT Fri Jun 18 2021

...HEAVY RAINFALL AND TROPICAL-STORM-FORCE WINDS SPREADING ACROSS
PORTIONS OF THE NORTHERN GULF COAST...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...27.9N 91.2W
ABOUT 125 MI...200 KM S OF MORGAN CITY LOUISIANA
ABOUT 270 MI...430 KM SW OF MOBILE ALABAMA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 5 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* East of Morgan City, Louisiana to the Okaloosa/Walton County line
Florida.
* Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, in this case within the
next 6-12 hours.

Interests elsewhere along the northern Gulf Coast should monitor
the progress of this system.

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.


DISCUSSION AND OUTLOOK
----------------------
At 400 PM CDT (2100 UTC), the disturbance was centered near latitude
27.9 North, longitude 91.2 West. The system is moving toward the
north near 16 mph (26 km/h) and a north to north-northeast motion
is expected during the next day or so.  On the forecast track, the
system will make landfall along the north-central Gulf Coast
tonight or early Saturday.  A northeastward or east-northeastward 
motion across the southeastern United States is forecast after 
landfall through the weekend.

Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Satellite images and surface observations indicate that the 
circulation is gradually becoming better defined, and the system 
still is likely to become a tropical or subtropical storm before 
landfall.  Regardless of its status, little change in strength is 
expected through landfall.  Weakening is forecast to begin after the 
system crosses the coast.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.

Tropical-storm-force winds extend outward up to 205 miles (335 km)
from the center.

The estimated minimum central pressure based on surface 
observations and Air Force Hurricane Hunter data is 1006 mb (29.71 
inches).


HAZARDS AFFECTING LAND
----------------------
Key messages for Potential Tropical Cyclone Three can be found in
the Tropical Cyclone Discussion under AWIPS header MIATCDAT3,
WMO header WTNT43 KNHC, and on the web at
www.hurricanes.gov/graphics_at3.shtml?key_messages.

RAINFALL: The potential tropical cyclone is expected to produce 
rainfall totals of 4 to 8 inches with isolated maximum amounts of 12 
inches across portions of the Central Gulf Coast. Considerable 
flash, urban and small stream flooding impacts as well as new and 
renewed minor to isolated moderate river flooding are likely. 

As the system continues to lift northeast through the weekend, heavy 
rain will expand across southeastern Mississippi, southern and 
central Alabama, central to northern Georgia, far western North 
Carolina and western South Carolina, resulting in rainfall totals of 
3 to 5 inches with isolated maximum amounts of 7 inches. Flash, 
urban, small stream and isolated minor river flooding impacts are 
possible. 

STORM SURGE:  The combination of 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...

Morgan City, LA to Okaloosa/Walton County Line, FL...2-3 ft
Lake Borgne and Mobile Bay...2-3 ft
Lake Pontchartrain and Lake Maurepas...1-2 ft
Okaloosa/Walton County Line, FL to Panama City, FL...1-2 ft
Pensacola Bay, Choctawhatchee Bay, and Saint Andrew Bay...1-2 ft
Cameron, LA to Morgan City, LA...1-2 ft
Vermilion Bay...1-2 ft

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 office.

WIND:  Tropical storm conditions are beginning to reach the coast
within the warning area, and these winds will continue into
Saturday.

TORNADOES: There is a threat for a tornado or two tonight
across coastal Louisiana.  A few tornadoes are possible on
Saturday across southern portions of Louisiana, Mississippi,
Alabama, and the western Florida Panhandle.

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