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BULLETIN
Potential Tropical Cyclone Three Intermediate Advisory Number 4A
NWS National Hurricane Center Miami FL       AL032021
100 PM CDT Fri Jun 18 2021
 
...DISTURBANCE A LITTLE STRONGER...
...HEAVY RAINFALL AND TROPICAL-STORM-FORCE WINDS BEGINNING TO REACH 
PORTIONS OF THE NORTHERN GULF COAST...
 
 
SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...27.3N 91.1W
ABOUT 165 MI...265 KM S OF MORGAN CITY LOUISIANA
ABOUT 295 MI...480 KM SSW OF MOBILE ALABAMA
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 15 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 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 100 PM CDT (1800 UTC), the disturbance was centered near latitude
27.3 North, longitude 91.1 West. The system is moving toward the
north near 14 mph (22 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 motion across the 
southeastern United States is likely after landfall through the 
weekend.
 
Satellite data indicate that maximum sustained winds have increased 
to near 45 mph (75 km/h) with higher gusts. The circulation is 
gradually becoming better defined, and a tropical storm is likely to 
form over the north-central Gulf of Mexico later today or tonight.
* 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 east of 
the center.  A NOAA C-MAN station at the Southwest Pass of the 
Mississippi River recently reported sustained winds of 44 mph (71 
km/h) and a wind gust of 51 mph (82 km/h) at an elevation of 125 
feet (38 meters).

The estimated minimum central pressure based on data from the Air
Force Hurricane Hunters and surface observations is 1007 mb (29.74
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: Rainfall totals of 4 to 8 inches with isolated maximum
amounts of 12 inches are expected across portions of the Central
Gulf Coast beginning today. 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,
anticipate heavy rain to expand across southeastern Mississippi,
southern and central Alabama, and central Georgia 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.
 
The potential tropical cyclone is expected to produce total
rainfall of 3 to 6 inches with isolated amounts of 8 inches across
the Yucatan Peninsula of Mexico.
 
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 this afternoon 
across coastal Louisiana, spreading overnight into Saturday across 
southern portions of Louisiana, Mississippi, Alabama, and the 
western Florida Panhandle.
 
 
NEXT ADVISORY
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Next complete advisory at 400 PM CDT.
 
$$
Forecaster Cangialosi
 
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