Ida intensifies overnight into catastrophic Cat 4 hurricane with 150 mph winds.
Yowza. When I went to bed, Ida was a Cat 2. I wake up and it has exploded into a dangerous Cat 4 monster that is still strengthening, threatening to make Cat 5 before landfall. Although, at this point, it doesn't really matter. An additional 7 mph wind isn't going to make much difference. If there's any good news, it's that Ida is jogging to the west so it looks like NOLA will miss a direct hit, but it will be on the "dirty" side of the storm which means it will be in the worst quadrant of the storm.
Hurricane Ida Discussion Number 12
NWS National Hurricane Center Miami FL AL092021
400 AM CDT Sun Aug 29 2021
Ida has undergone some dramatic inner-core structural changes since
the previous advisory. The eye between 25,000-45,000 ft has become
circular with a diameter of about 15 nmi now, and at least two
eyewall mesocyclones have been noted rotating cyclonically around
the eyewall in both radar and high-resolution 1-minute GOES-16
satellite imagery. The result has been rapid strengthening of at
least 30 kt during the past 6 hours, along with a pressure drop of
more than 15 mb during that same time, with a 6-mb decrease having
occurred in the 1-hr period between about 0500-0600 UTC based on Air
Force Reserve reconnaissance aircraft eye dropsonde data. The
aircraft also measured a maximum 700-mb flight-level wind speed of
133 kt in the northeastern quadrant, along with a peak SFMR surface
wind speed of 116 kt. Furthermore, NWS Doppler radar velocity data
from Slidell, Louisiana, has recently been measuring velocities of
120-130 kt between 25,000-30,000 ft, which is quite rare, and
indicates that Ida is a vertically deep and intense hurricane. Ida
was initialized with 115 kt at 0600 UTC, but the 0900 UTC advisory
intensity has been increased to 120 kt based on the 133-kt
flight-level wind and the improved structure in both radar data and
satellite imagery since the 0609 UTC time of that aircraft
observation.
The initial motion remains northwestward, or 315/13 kt. There is no
significant change to the previous forecast track or synoptic
reasoning. The subtropical ridge oriented east-west along 30N-31N
across the southeastern U.S. is forecast to remain intact through
the forecast period with only minor shifts in the location and
strength of the ridge. As a result, Ida should continue to move
northwestward toward the southeastern Louisiana coast today,
followed by a gradual turn toward the north tonight after landfall.
On Monday, the hurricane is expected to move northeastward across
the Tennessee Valley when Ida moves north of the ridge axis.
Impacts and hazards will arrive well before the eye of the hurricane
makes landfall. Tropical-storm-force winds are likely to begin later
this morning. Therefore, all preparations to protect life and
property must be rushed to completion. The new track forecast is
basically just an update of the previous advisory track.
Ida will remain over waters with high oceanic heat content for
another 6 hours or so. Thereafter, the heat content will drop
sharply to less than half of the current value of more than 100
units. However, some additional strengthening is expected until
landfall occurs. After Ida moves inland tonight, rapid weakening is
forecast due to a combination of land interaction, entrainment
of drier air, and some increase in westerly vertical wind shear.
Users are again reminded to not focus on the exact details of the
track forecast as storm surge, wind, and rainfall impacts will
extend far from the center. Rainfall impacts will also spread
inland across the Lower Mississippi and Tennessee Valleys through
early next week.
Key Messages:
1. There is a danger of life-threatening storm surge inundation
Sunday along the coasts of Louisiana, Mississippi, and Alabama
within the Storm Surge Warning area. Extremely life-threatening
inundation of 9 feet or greater above ground level is possible
somewhere within the area from Morgan City, Louisiana, to the coast
of Mississippi. Overtopping of local levees outside of the Hurricane
and Storm Damage Risk Reduction System is possible where local
inundation values may be higher. Interests throughout the warning
area should follow any advice given by local officials.
2. Ida is expected to be an extremely dangerous major hurricane when
it reaches the coast of southeastern Louisiana. Hurricane-force
winds are expected Sunday in portions of the Hurricane Warning area
along the Louisiana coast, including metropolitan New Orleans, with
potentially catastrophic wind damage possible where the core of Ida
moves onshore. Actions to protect life and property should be rushed
to completion in the warning area.
3. Damaging winds, especially in gusts, will spread inland near the
track of the center of Ida across portions of southeastern Louisiana
and southwestern Mississippi Sunday night and early Monday. These
winds will likely lead to widespread tree damage and power outages.
4. Ida will produce heavy rainfall today through Monday across the
central Gulf Coast from southeastern Louisiana, coastal Mississippi,
to far southwestern Alabama resulting in considerable to
life-threatening flash and urban flooding and significant riverine
flooding impacts. As Ida moves inland, significant flooding impacts
are possible across portions of the Lower Mississippi, Tennessee,
and Ohio Valleys through Wednesday.
FORECAST POSITIONS AND MAX WINDS
INIT 29/0900Z 28.0N 89.1W 120 KT 140 MPH
12H 29/1800Z 29.1N 90.3W 125 KT 145 MPH...NEAR SERN LOUISIANA
24H 30/0600Z 30.6N 91.1W 70 KT 80 MPH...INLAND
36H 30/1800Z 32.2N 91.0W 45 KT 50 MPH...INLAND
48H 31/0600Z 33.8N 90.0W 30 KT 35 MPH...INLAND
60H 31/1800Z 35.4N 87.9W 25 KT 30 MPH...INLAND
72H 01/0600Z 36.7N 85.2W 20 KT 25 MPH...INLAND
96H 02/0600Z 38.9N 78.9W 20 KT 25 MPH...POST-TROP/INLAND
120H 03/0600Z...DISSIPATED
$$
Forecaster Stewart
National Hurricane Center
= new reply since forum marked as read
Not good. Stay safe Gulf Coast.
