Yet another storm with rapid intensification that perhaps we didnt see in past decades. The last NHC advisory suggests a few more hours of strengthening possible so Cat 5 cannot be ruled out
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.
"We have some alternative facts for you"
Kelly-Ann Conway - special adviser to the President