[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 300250
TCDAT4

Hurricane Ian Discussion Number  30
NWS National Hurricane Center Miami FL       AL092022
1100 PM EDT Thu Sep 29 2022

Ian continues to have the appearance of a hybrid tropical cyclone,
having the characteristics of both an extratropical low with some
frontal features, and a sheared tropical cyclone with convection
well removed from the low-level center.  The system is interacting
with a mid- to upper-level shortwave trough just to its west, and
this interaction may be contributing to slight strengthening. Based
on a blend of flight-level and SFMR-observed winds, along with
dropsonde measurements, from an Air Force Hurricane Hunter aircraft
the current intensity has been increased a little to 70 kt for this
advisory.  The strongest winds are currently occuring over the
northwestern quadrant of the hurricane.

Southwesterly vertical wind shear is expected to remain high and the
environmental air mass will stay dry until landfall.  However, Ian
could intensify a little more within the next 12 hours or so due to
trough interaction and extraction of energy from the underlying warm
Gulf Stream waters.  Therefore the NHC forecast calls for slight
strengthening before the system reaches the coast. This is above the
available intensity model guidance.   It should be emphasized that
although Ian is not expected to be a classic hurricane at landfall,
this does not diminish the threat it poses.  Strong winds and storm
surge will also extend far from the center and will begin well
before the center arrives.

Ian continues to move north-northeastward at about 030/9 kt. Over
the next day or so, the cyclone is expected to turn northward and
then north-northwestward as it moves along the eastern side of the
shortwave trough.  The dynamical model consensus, TVCN, has again
shifted slightly eastward on this cycle.  Therefore the NHC track
prediction is, again, moved a little eastward from the previous
official forecast.


Key Messages:

1. There is a danger of life-threatening storm surge through Friday
along the coasts of northeast Florida, Georgia, and South Carolina.
Residents in these areas should follow any advice given by local
officials.

2. Hurricane-force winds are expected across the coasts of South
Carolina and southeastern North Carolina beginning early Friday,
where a Hurricane Warning is in effect.  Hurricane conditions are
possible in North Carolina on Friday where a Hurricane Watch is in
effect.   Preparations should be rushed to completion.

3. Ongoing major to record river flooding will continue through next
week across portions of central Florida.  Considerable flooding is
expected through Friday across portions of coastal and northeast
South Carolina. Locally considerable flooding is possible across
portions of North Carolina and southern Virginia through Friday.


FORECAST POSITIONS AND MAX WINDS

INIT  30/0300Z 30.2N  79.3W   70 KT  80 MPH
 12H  30/1200Z 31.7N  79.1W   75 KT  85 MPH
 24H  01/0000Z 34.0N  79.6W   60 KT  70 MPH...INLAND
 36H  01/1200Z 36.0N  80.4W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  02/0000Z 37.5N  81.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 60H  02/1200Z...DISSIPATED

$$
Forecaster Pasch
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