BULLETIN
Hurricane Ida Advisory Number 9
NWS National Hurricane Center Miami FL AL092021
1000 AM CDT Sat Aug 28 2021
…IDA EXPECTED TO BEGIN RAPIDLY INTENSIFYING SOON…
…PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO
COMPLETION TODAY IN THE WARNING AREA ALONG THE NORTHERN GULF
COAST…
SUMMARY OF 1000 AM CDT…1500 UTC…INFORMATION
———————————————–
LOCATION…24.8N 86.1W
ABOUT 350 MI…565 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 435 MI…700 KM SE OF HOUMA LOUISIANA
MAXIMUM SUSTAINED WINDS…85 MPH…140 KM/H
PRESENT MOVEMENT…NW OR 315 DEGREES AT 16 MPH…26 KM/H
MINIMUM CENTRAL PRESSURE…984 MB…29.06 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning has been extended eastward along the
northern Gulf coast to the Alabama/Florida border.
The Hurricane Watch along the coast of Mississippi from the Mouth
of the Pearl River to the Mississippi/Alabama border has been
discontinued. The Hurricane Watch along the coast of Louisiana
west of Intracoastal City has also been discontinued.
The Storm Surge Watch from Sabine Pass to Rockefeller Wildlife
Refuge, Louisiana has been discontinued.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for…
* East of Rockefeller Wildlife Refuge Louisiana to the
Mississippi/Alabama border
* Vermilion Bay, Lake Borgne, Lake Pontchartrain, and Lake Maurepas
A Hurricane Warning is in effect for…
* Intracoastal City Louisiana to the Mouth of the Pearl River
* Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans
A Storm Surge Watch is in effect for…
* Mobile Bay
A Tropical Storm Warning is in effect for…
* Cameron Louisiana to west of Intracoastal City Louisiana
* Mouth of the Pearl River to the Alabama/Florida border
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 Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. A warning is typically issued
36 hours before the anticipated first occurrence of
tropical-storm-force winds, conditions that make outside
preparations difficult or dangerous. Preparations to protect life
and property should be rushed to completion.
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 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 1000 AM CDT (1500 UTC), the center of Hurricane Ida was located
near latitude 24.8 North, longitude 86.1 West. Ida is moving toward
the northwest near 16 mph (26 km/h), and this general motion should
continue through late Sunday or early Monday, followed by a slower
northward motion on Monday. On the forecast track, the center of
Ida will move over the southeastern Gulf of Mexico today and move
over the central Gulf of Mexico tonight and early Sunday. Ida is
then expected to make landfall along the U.S. northern Gulf coast
within the hurricane warning area on Sunday, and then move inland
over portions of Louisiana or western Mississippi later on Monday.
Maximum sustained winds are near 85 mph (140 km/h) with higher
gusts. Rapid strengthening is forecast during the next 24 to 36
hours and Ida is expected to be an extremely dangerous major
hurricane when it approaches the northern Gulf coast on Sunday.
Weakening is expected after Ida makes landfall.
Hurricane-force winds extend outward up to 30 miles (45 km) from the
center and tropical-storm-force winds extend outward up to 125 miles
(205 km).
The latest minimum central pressure estimated from Air Force
Reserve reconnaissance aircraft data is 984 mb (29.06 inches).
HAZARDS AFFECTING LAND
———————-
Key messages for Ida 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.
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…
Morgan City, LA to Mouth of the Mississippi River…10-15 ft
Mouth of the Mississippi River to Ocean Springs, MS including Lake
Borgne…7-11 ft
Intracoastal City, LA to Morgan City, LA including Vermilion
Bay…6-9 ft
Ocean Springs, MS to MS/AL border…4-7 ft
Lake Pontchartrain…4-7 ft
Lake Maurepas…3-5 ft
Pecan Island, LA to Intracoastal City, LA…3-5 ft
MS/AL border to AL/FL border including Mobile Bay…2-4 ft
Sabine Pass to Pecan Island, LA…1-3 ft
Overtopping of local levees outside of the Hurricane and Storm
Damage Risk Reduction System is possible where local inundation
values may be higher than those shown above.
The deepest water will occur along the immediate coast near and to
the east of the landfall location, 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 office.
WIND: Hurricane conditions are expected in the hurricane warning
area along the Louisiana coast beginning Sunday with tropical storm
conditions expected to begin by late tonight or early Sunday
morning. These conditions will spread inland over portions of
Louisiana and Mississippi Sunday night and Monday.
RAINFALL: Heavy rainfall from Ida will begin to impact the
Louisiana coast Sunday morning, spreading northeast into the Lower
Mississippi Valley later Sunday into Monday. Total rainfall
accumulations of 8 to 16 inches with isolated maximum amounts of 20
inches are possible across southeast Louisiana and southern
Mississippi through Monday. This is likely to result in
life-threatening flash and urban flooding impacts and significant
riverine flooding impacts.
Ida is forecast to turn northeast later Monday, with rainfall totals
of 4 to 8 inches possible from northeastern Louisiana and central
Mississippi into the Tennessee Valley. This is likely to result in
considerable flash and riverine flooding impacts.
Rainfall impacts from Ida will diminish across western Cuba today
as the storm continues to lift northward away from the island. An
additional 1 to 2 inches of rain with isolated maximum amounts of 4
inches are possible across western Cuba through today. These
rainfall amounts may produce flash floods and mudslides.
TORNADOES: Tornadoes will be possible Sunday into Monday across
the northern Gulf coast states including parts of eastern
Louisiana, Mississippi, central and southern Alabama, and the
Florida Panhandle. The longest duration tornado threat will exist
across southeast Louisiana and southern Mississippi.
SURF: Swells generated by Ida will continue to affect western Cuba
through today. Swells will begin reaching portions of the northern
Gulf coast later today and continue through Monday. These swells
are likely to cause life-threatening surf and rip current
conditions. Please consult products from your local weather office.
