[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 280254
TCDAT4

Hurricane Ian Discussion Number  20
NWS National Hurricane Center Miami FL       AL092022
1100 PM EDT Tue Sep 27 2022

The hurricane continues to have an impressive appearance on
satellite imagery, exhibiting considerable deep convection with
numerous cloud tops colder than -80C.  An Air Force Hurricane
Hunter Aircraft recently penetrated the center and found that the
central pressure had not fallen since earlier this evening.  Based
on a blend of SFMR-observed surface winds and 700 mb flight-level
winds from the Air Force plane, the current intensity is held at
105 kt for now.

Ian has turned slightly to the right and the initial motion is now
015/9 kt.  Over the next couple of days, the tropical cyclone
should move between the western edge of a subtropical high
pressure system and a broad trough over the eastern United
States.  The dynamical model consensus, TVCN, prediction has again
shifted a little to the east, and is just slightly slower on
this cycle.  Therefore the official track forecast has, again, been
shifted a few degrees to the east of the previous one.  This
does not require any change the watches and warnings over Florida at
this time.

Ian's outflow is being restricted over the southwestern portion of
its circulation by southwesterly upper-tropospheric flow over the
Gulf of Mexico.  Vertical shear over the hurricane is likely to
increase up through landfall. The SHIPS guidance and water vapor
imagery suggest that there will also be some dry mid-level air in
the vicinity.   However, it is expected that this large system will
be fairly resilient to the shear and dry air before landfall.
Therefore, the official intensity forecast continues to show Ian
reaching the coast with category 4 intensity.  Since radar imagery
indicates that an eyewall replacement is probably underway,  this
could result in a larger eye evolving overnight.  Interests along
the Florida west coast in the Hurricane Warning area should be
prepared for a large and destructive hurricane, and residents in
this area should heed the advice of emergency management officials.
Users are reminded to not focus on the exact forecast track as some
additional adjustments to the track are possible, and significant
wind, storm surge, and rainfall hazards will extend far from the
center.


Key Messages:

1. Life-threatening storm surge is expected along the Florida west
coast where a storm surge warning is in effect, with the highest
risk from Naples to the Sarasota region. Residents in these areas
should listen to advice given by local officials and follow any
evacuation orders for your area.

2. Hurricane-force winds are expected in the hurricane warning area
in southwest and west-central Florida beginning Wednesday morning
with tropical storm conditions expected overnight.  Devastating wind
damage is expected near the core of Ian. Residents should rush all
preparations to completion.

3. Heavy rainfall will spread across the Florida peninsula through
Thursday and reach portions of the Southeast later this week and
this weekend.  Catastrophic flooding is expected across portions of
central Florida with considerable flooding in southern Florida,
northern Florida, southeastern Georgia and coastal South Carolina.
Widespread, prolonged moderate to major river flooding expected
across central Florida.


FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 24.9N  82.9W  105 KT 120 MPH
 12H  28/1200Z 26.0N  82.5W  115 KT 130 MPH
 24H  29/0000Z 27.2N  81.9W  110 KT 125 MPH...INLAND
 36H  29/1200Z 28.2N  81.4W   60 KT  70 MPH...INLAND
 48H  30/0000Z 29.3N  80.8W   45 KT  50 MPH...OVER WATER
 60H  30/1200Z 30.6N  80.8W   45 KT  50 MPH
 72H  01/0000Z 32.7N  81.2W   30 KT  35 MPH...INLAND
 96H  02/0000Z 36.0N  82.5W   25 KT  30 MPH...POST-TROP/INLAND
120H  03/0000Z...DISSIPATED

$$
Forecaster Pasch
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