UNIQUE IDENTIFIER: r
TIME (e.g. 1800 UTC SAT FEB 22 2020): 0900 UTC MON AUG 30 2021
ADVISORY HEADLINE: IDA NOW A TROPICAL STORM OVER SOUTHWESTERN MISSISSIPPI


INPUT INTERP ATCF: al092021 IDA 20210829 0900 31.00 -90.8 L TS 50.00 990.0 13.04 315.00
ADVISORY NUMBER: 9


NEXT ADVISORY TIME (e.g. SEP 16 2021, 1800 UTC)

Please allow time for floater to build.

• STORM FLOATER •

  L ()
PUBLIC ADVISORY #
FORCE THIRTEEN , 

 
......
 
SUMMARY OF INFORMATION
-----------------------------------
LOCATION...NEAR    ...
MAXIMUM SUSTAINED WINDS...MPH...KM/H
MINIMUM CENTRAL PRESSURE...MB
 
WATCHES AND WARNINGS
-----------------------------------
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


DISCUSSION
-----------------------------------
Ida is now located well inland over southwestern Mississippi and
weakening rapidly. However, Doppler velocity data from the Slidell,
Louisiana, WSR-88D radar before it went down was still indicating
velocity values near 90 kt between 4,000-4,500 ft, while the latest
velocity data from Jackson, Mississippi, have been in the 70-75 kt
range between 7,500 and 8,000 ft well east of the center. Thus, Ida
will still be capable of producing damaging wind gusts in some of
the stronger showers and thunderstorms for the next few hours. The
intensity at 0600 UTC was 65 kt, which was based on a decay rate of
about 10 kt per hour. A slightly slower decay rate of about 5 kt
per hour has been used since then, which is the basis for the 50-kt
advisory intensity at 0900 UTC. The estimated pressure of 990 mb is
based on surface observation data, especially from McComb,
Mississippi (KMCB), which has been reporting pressures near 995 mb
with 25-30 kt of wind the past couple of hours.

Rapid weakening will continue as Ida moves farther inland over 
Mississippi due to land interaction and southwesterly vertical wind 
shear of more than 20 kt. However, damaging winds, especially in 
gusts, are expected to continue over southeastern Louisiana and 
southwestern Mississippi through through this morning.  To account 
for this, the gust factor in the Forecast/Advisory has been adjusted 
accordingly.  Ida is likely to weaken to a tropical depression this 
evening. Some slight restrengthening as an extratropical storm is 
possible when Ida moves over the western Atlantic in the day 4-5 
period.  In addition, heavy rains will spread northward and then 
northeastward along the forecast track.

LOCAL AND OFFICIAL SOURCES BELOW
National Hurricane Center (Atlantic)
 

 
$$
Forecaster 

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