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Tropical Storm Ida Intermediate Advisory Number 17A
NWS National Hurricane Center Miami FL AL092021
700 AM CDT Mon Aug 30 2021
...IDA MOVING NORTHWARD OVER SOUTHWESTERN MISSISSIPPI...
...DANGEROUS STORM SURGE AND FLASH FLOODING CONTINUES OVER PORTIONS
OF SOUTHEASTERN LOUISIANA, SOUTHERN MISSISSIPPI, AND SOUTHERN
SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
ABOUT 65 MI...105 KM SSW OF JACKSON MISSISSIPPI
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...993 MB...29.32 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
*Grand Isle, Louisiana, to the Alabama/Florida border
A Tropical Storm Warning is in effect for...
* Grand Isle, Louisiana, to the Alabama/Florida border, including
Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans
A Storm Surge Warning means there is a danger of life-threatening
inundation from rising water moving inland from the coastline 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.
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 700 AM CDT (1200 UTC), the center of Tropical Storm Ida was
located by NOAA Doppler weather radars, satellite data, and surface
observations near latitude 31.5 North, longitude 90.8 West. Ida is
moving toward the north near 8 mph (13 km/h), and this general
motion is forecast to continue today. A faster northeastward motion
is expected to begin by tonight and continue on Tuesday. On the
forecast track, the center of Ida will move farther inland over
southwestern Mississippi this morning. Ida is then forecast to move
over central and northeastern Mississippi this afternoon and
tonight, and move across the Tennessee Valley on Tuesday.
Maximum sustained winds have decreased to near 45 mph (75 km/h) with
higher gusts. Additional rapid weakening is forecast during the next
day or so, and Ida is expected to become a tropical depression this
Tropical-storm-force winds extend outward up to 150 miles (240 km),
mainly southeast of the center over water. A coastal marine
observing site at Dauphin Island, Alabama, recently reported
sustained winds of 38 mph (61 km/h) and a gust to 46 mph (74 km/h).
A wind gust to 45 mph (72 km/h) was recently measured at Biloxi,
The estimated minimum central pressure is 993 mb (29.32 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...
Pointe a la Hache, LA to Bay St. Louis, MS including Lake
Lake Maurepas and Lake Pontchartrain...4-6 ft
Bay St. Louis, LA to AL/FL border including Mobile Bay...3-5 ft
Grand Isle, LA to Pointe a la Hache, LA...2-4 ft
Morgan City, LA to Grand Isle, LA...1-3 ft
AL/FL border to Okaloosa/Walton County Line including Pensacola
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: Tropical storm conditions will continue over portions of
Louisiana, southern Mississippi, and southern Alabama through this
morning or early afternoon.
RAINFALL: Through Tuesday morning, Ida will produce additional
rainfall totals of 4 to 8 with localized higher amounts possible
across portions of southeast Louisiana into far southern
Mississippi. Storm total rainfall accumulations of 10 to 18 inches
with isolated maximum amounts of 24 inches is expected. Heavy rain
combined with storm surge has resulted in catastrophic impacts along
the southeast coast of Louisiana with life threatening flash
flooding and significant riverine flooding continuing farther
Ida is expected to turn northeast this morning and is forecast to
track across the Middle Tennessee Valley, Ohio Valley and
Mid-Atlantic through Wednesday, producing the following rainfall
Coastal Alabama to the far western Florida panhandle: An additional
4 to 8 inches resulting in storm total accumulations of 6 to 12
inches with isolated maximum amounts of 15 inches, today through
Central Mississippi into far western Alabama: 4 to 8 inches with
isolated maximum amounts of 12 inches, today through tonight.
Middle Tennessee Valley, Ohio Valley, Central/Southern Appalachians
into the Mid-Atlantic: 3 to 6 inches with isolated higher amounts,
Tuesday into Wednesday.
Considerable flash flooding is possible from the Lower Mississippi
Valley through the Middle Tennessee Valley, Ohio Valley,
Central/Southern Appalachians, and into the Mid-Atlantic. Widespread
minor to isolated major riverine flooding is possible from the Lower
Mississippi Valley into far western Alabama through Wednesday.
TORNADOES: A few tornadoes are possible today into tonight, mainly
across southeast Mississippi, southwest Alabama, and the western
SURF: Swells will continue to affect portions of the northern Gulf
coast through today. These swells are likely to cause
life-threatening surf and rip current conditions. Please consult
products from your local weather office.
Next complete advisory at 1000 AM CDT.