[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 100854
TCDAT4

Hurricane Michael Discussion Number  15
NWS National Hurricane Center Miami FL       AL142018
400 AM CDT Wed Oct 10 2018

Reports from an Air Force Reserve Hurricane Hunter aircraft
indicate that Michael has continued to strengthen during the past
several hours.  The maximum flight-level winds at 700 mb have been
136 kt, and the maximum surface wind estimates from the Stepped
Frequency Microwave Radiometer are in the 120-125 kt range.  In
addition, the central pressure has fallen to near 943 mb.  Based on
on the aircraft data, the initial intensity is increased to 120 kt.
This is a little below the satellite intensity estimates from TAFB,
SAB, and the CIMSS satellite consensus.  The cirrus outflow
associated with Michael has improved over the past several hours,
with the outflow flowing into an upper-level low to the southeast
and along the east side of a large mid-latitude trough to the west.

The initial motion is 360/11.  Michael is embedded in the flow
between a large mid- to upper-level ridge over the western Atlantic
and the northeastern United States and the aforementioned trough
across the central United States.  These features should cause the
hurricane to turn north-northeastward during the next 12 h or so,
followed by a turn toward the northeast and a significant increase
in forward speed.  Near the end of the forecast period, Michael or
its remnants should turn more eastward. The forecast track calls for
the eye to make landfall in the Florida Panhandle at about the 12 h
point, followed by a northeastward motion across the southeastern
United States between 12-48 h.  The forecast guidance remains
tightly clustered, and the new forecast track is very close to the
previous track and the various consensus models through 72 h.

Additional strengthening is expected before landfall as Michael
remains over warm water and in an environment of light to moderate
vertical shear.  After landfall, Michael is expected to steadily
weaken as it crosses the southeastern United States.  Extratropical
transition is expected to begin while Michael is over land, and
this should be complete just after the 48 h point.  The cyclone
should re-intensify due to baroclinic forcing as it moves rapidly
northeastward over the north Atlantic.  The new intensity forecast
has been nudged upward at the landfall time based on current
trends.  Otherwise, it is an update of the previous forecast.

Tropical storm conditions are expected to reach the hurricane
warning area during the next few hours, so all preparations should
be rushed to completion.

Key Messages:

1. Life-threatening storm surge is likely along portions of the
coasts of the Florida Panhandle, Big Bend, and Nature Coast, where
a storm surge warning is in effect. The worst storm surge is
expected between Tyndall Air Force Base and Keaton Beach, where 9 to
13 feet of inundation is possible.

2. Michael is likely to produce potentially catastrophic wind
damage where the core of the hurricane moves onshore in the Florida
Panhandle, and everyone in the hurricane warning area should
prepare for life-threatening hurricane winds.  Dangerous hurricane-
force winds will also extend well inland across portions of the
Florida Panhandle, southern Georgia, and southeast Alabama as
Michael moves inland.

3. Heavy rainfall from Michael could produce life-threatening flash
flooding from the Florida Panhandle and Big Bend region into
portions of Georgia, the Carolinas, and southeast Virginia.

4. Tropical storm conditions will likely affect portions of the
southeast U.S. coast from northeast Florida through North Carolina,
and tropical storm watches and warnings are in effect for these
areas.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 28.3N  86.5W  120 KT 140 MPH
 12H  10/1800Z 29.9N  85.7W  125 KT 145 MPH
 24H  11/0600Z 32.1N  83.8W   65 KT  75 MPH...INLAND
 36H  11/1800Z 34.4N  80.5W   40 KT  45 MPH...INLAND
 48H  12/0600Z 36.8N  75.6W   40 KT  45 MPH...OVER WATER
 72H  13/0600Z 43.5N  59.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  14/0600Z 49.5N  36.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  15/0600Z 52.0N  17.5W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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