
NWS NATIONAL HURRICANE CENTER MIAMI FL AL032021
2100 UTC THU JUN 17 2021
CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...
A TROPICAL STORM WARNING HAS BEEN ISSUED FOR THE GULF COAST
FROM INTRACOASTAL CITY...LOUISIANA...TO THE ALABAMA/FLORIDA
BORDER...INCLUDING LAKE PONTCHARTRAIN...LAKE MAUREPAS...AND
METROPOLITAN NEW ORLEANS.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT...
A TROPICAL STORM WARNING IS IN EFFECT FOR...
* INTRACOASTAL CITY LOUISIANA TO THE ALABAMA/FLORIDA BORDER
* LAKE PONTCHARTRAIN...LAKE MAUREPAS...AND METROPOLITAN NEW ORLEANS
A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.
INTERESTS ELSEWHERE ALONG THE NORTHERN GULF COAST SHOULD MONITOR
THE PROGRESS OF THIS SYSTEM.
POTENTIAL TROP CYCLONE CENTER LOCATED NEAR 22.9N 92.4W AT 17/2100Z
POSITION ACCURATE WITHIN 60 NM
PRESENT MOVEMENT TOWARD THE NORTH OR 360 DEGREES AT 8 KT
ESTIMATED MINIMUM CENTRAL PRESSURE 1008 MB
MAX SUSTAINED WINDS 25 KT WITH GUSTS TO 35 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.
REPEAT...CENTER LOCATED NEAR 22.9N 92.4W AT 17/2100Z
AT 17/1800Z CENTER WAS LOCATED NEAR 22.5N 92.4W
FORECAST VALID 18/0600Z 24.5N 92.5W...TROPICAL CYCLONE
MAX WIND 25 KT...GUSTS 35 KT.
FORECAST VALID 18/1800Z 26.5N 92.5W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT...150NE 150SE 0SW 0NW.
FORECAST VALID 19/0600Z 29.0N 92.0W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT...180NE 180SE 0SW 0NW.
FORECAST VALID 19/1800Z 31.5N 89.5W...INLAND
MAX WIND 30 KT...GUSTS 40 KT.
FORECAST VALID 20/0600Z 34.0N 87.0W...INLAND
MAX WIND 25 KT...GUSTS 35 KT.
FORECAST VALID 20/1800Z 35.0N 84.0W...INLAND
MAX WIND 20 KT...GUSTS 30 KT.
EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM
ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY
OUTLOOK VALID 21/1800Z...DISSIPATED
REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 22.9N 92.4W
INTERMEDIATE PUBLIC ADVISORY...WTNT33 KNHC/MIATCPAT3...AT 18/0000Z
NEXT ADVISORY AT 18/0300Z
$$
FORECASTER PASCH
BULLETIN
Potential Tropical Cyclone Three Advisory Number 1
NWS National Hurricane Center Miami FL AL032021
400 PM CDT Thu Jun 17 2021
...POTENTIAL TROPICAL CYCLONE OVER THE SOUTHWESTERN GULF OF
MEXICO...
...EXPECTED TO BRING HEAVY RAINFALL AND FLOODING TO THE NORTHERN
GULF COAST...
SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.9N 92.4W
ABOUT 475 MI...765 KM S OF MORGAN CITY LOUISIANA
MAXIMUM SUSTAINED WINDS...30 MPH...45 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
A Tropical Storm Warning has been issued for the Gulf Coast from
Intracoastal City, Louisiana, to the Alabama/Florida border,
including Lake Pontchartrain, Lake Maurepas, and Metropolitan New
Orleans.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for...
* Intracoastal City Louisiana to the Alabama/Florida border
* Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
Interests elsewhere along the northern Gulf Coast should monitor
the progress of this system.
DISCUSSION AND OUTLOOK
----------------------
At 400 PM CDT (2100 UTC), the disturbance was centered near latitude
22.9 North, longitude 92.4 West. The system is moving toward the
north near 9 mph (15 km/h) and this motion with some increase in
forward speed is expected for the next day or so. On the
forecast track, the system will approach the north-central
Gulf Coast late Friday or early Saturday. A northeastward motion
across the southeastern United States is likely after landfall.
Maximum sustained winds are near 30 mph (45 km/h) with higher gusts.
Some strengthening is forecast tonight and Friday.
A subtropical or tropical depression or storm is likely to form
over the west-central Gulf of Mexico tonight or early Friday.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.
The estimated minimum central pressure is 1008 mb (29.77 inches).
HAZARDS AFFECTING LAND
----------------------
Key messages for Potential Tropical Cyclone Three can be found in
the Tropical Cyclone Discussion under AWIPS header MIATCDAT3 and
WMO header WTNT43 KNHC.
RAINFALL: 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. Rainfall totals of
4 to 8 inches with isolated maximum amounts of 12 inches are
possible beginning Friday and continuing through the weekend from
the Central Gulf coast northeastward into the Southern Appalachians.
This will likely produce areas of flash, urban, and small stream
flooding as well as minor to isolated moderate river flooding with
new and renewed rises on already elevated rivers.
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...
Intracoastal City, LA to MS/AL Border...2-3 ft
Vermilion Bay and Lake Borgne...2-3 ft
Lake Pontchartrain and Lake Maurepas...1-2 ft
MS/AL border to AL/FL border including Mobile Bay...1-3 ft
Cameron, LA to Intracoastal City, LA...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 expected to first reach the
coast within the warning area on Friday, making outside
preparations difficult or dangerous.
TORNADOES: The threat for a couple tornadoes should begin Friday
afternoon across coastal Louisiana. This threat should expand
northward across southern portions of Louisiana and Mississippi, and
southwest Alabama on Saturday.
NEXT ADVISORY
-------------
Next intermediate advisory at 700 PM CDT.
Next complete advisory at 1000 PM CDT.
$$
Forecaster Pasch
Potential Tropical Cyclone Three Discussion Number 1
NWS National Hurricane Center Miami FL AL032021
400 PM CDT Thu Jun 17 2021
Visible satellite images show that the cloud pattern associated with
the broad area of low pressure located over the southwestern Gulf of
Mexico is gradually becoming better organized. Deep convection is
beginning to form a broad curved band over the eastern portion of
the system, similar to what one might see in a developing
subtropical cyclone. Although the upper-level winds are not
particularly favorable for development, with lots of westerly shear
over the area, the global models do suggest tropical/subtropical
cyclogenesis within the next 12 hours or so. Given the proximity of
the disturbance to land, which requires tropical storm warnings at
this time, advisories are being initiated on this system as a
potential tropical cyclone.
Earlier scatterometer data suggested that the circulation was still
rather broad. An Air Force Hurricane Hunter plane is currently
investigating the system and has not yet found a well-defined
center. Maximum winds based on surface observations and the
scatterometer pass are near 25 kt. Numerical intensity guidance do
not indicate a great deal of strengthening before the system
reaches the coastline, and the official forecast is at the high end
of the guidance.
Since the center is not that well-defined at this time, the initial
motion estimate, 360/8 is quite uncertain. The system is expected
to move northward into a weakness in the subtropical ridge for the
next day or so and then, after landfall along the central Gulf
Coast, turn toward the northeast on the northwest side of a
mid-level anticyclone near Florida. The official track forecast is
closest to the GFS and ECMWF predictions. It should be noted,
however, that these models suggest some reformation of the center
near the Louisiana coast rather than just motion from the southwest
Gulf to the expected coastal landfall point.
Given the current and anticipated structure of this system, users
should not focus on the exact track of the center, as rainfall and
wind hazards are likely to extend well east of the center and arrive
well in advance of landfall.
Key Messages:
1. The system is expected to produce heavy rainfall and considerable
flash, urban, and small stream flooding beginning Friday and
continuing through the weekend along the central Gulf coast and
spreading northeastward into the Southern Appalachians.
2. Tropical storm conditions are expected to begin Friday in areas
near and well to the east of the center along portions of the
central Gulf Coast from Intracoastal City, Louisiana, to the
Alabama/Florida border, including New Orleans.
FORECAST POSITIONS AND MAX WINDS
INIT 17/2100Z 22.9N 92.4W 25 KT 30 MPH...POTENTIAL TROP CYCLONE
12H 18/0600Z 24.5N 92.5W 25 KT 30 MPH...TROPICAL CYCLONE
24H 18/1800Z 26.5N 92.5W 35 KT 40 MPH
36H 19/0600Z 29.0N 92.0W 40 KT 45 MPH
48H 19/1800Z 31.5N 89.5W 30 KT 35 MPH...INLAND
60H 20/0600Z 34.0N 87.0W 25 KT 30 MPH...INLAND
72H 20/1800Z 35.0N 84.0W 20 KT 25 MPH...INLAND
96H 21/1800Z...DISSIPATED
$$
Forecaster Pasch/Brennan