705
WTNT44 KNHC 112053
TCDAT4

Tropical Storm Michael Discussion Number 21
NWS National Hurricane Center Miami FL AL142018
500 PM EDT Thu Oct 11 2018

Satellite and radar data show that Michael's rain shield is
beginning to expand northward and northwestward, and that cooler and
drier air is starting to wrap around the western portion of the
circulation. These trends indicate that Michael's transition to an extratropical low has started. There have been recent observations
of 40 to nearly 45 kt sustained winds along the southeastern coast
of North Carolina, so the initial intensity remains 45 kt. Little
change in strength is expected through this evening, but Michael is
forecast to quickly intensify after it completes extratropical
transition and exits the east coast of the United States tonight.
The official intensity forecast is based on guidance from the NOAA
Ocean Prediction Center.

It should also be noted that an area of damaging wind gusts of up to
50 kt has developed around the northwest side of the circulation
over central North Carolina and Virginia this afternoon. As a
result, the gust factor has been increased in this advisory, as this
area of strong winds will spread northward and eastward across
portions of eastern Virginia and northeastern North Carolina this
evening and tonight.

Michael is moving northeastward or 050/21 kt. The storm will
continue to accelerate as it become further embedded within the
mid-latitude westerlies. The post-tropical cyclone will race
across the north Atlantic during the next few days, before slowing
down late in the period before it weakens and dissipates. The
track guidance continues to be in good agreement and little change
was required from the previous NHC track forecast.

Gale- to storm-force winds are expected over portions of the
Mid-Atlantic coast as Michael exits the U.S. east coast and becomes post-tropical. Non-tropical high wind watches, warnings, and
advisories have been issued by local NWS offices for wind hazards in
these areas north of Duck, North Carolina.

Key Messages:

1. Life-threatening flash flooding is occurring over portions of
North Carolina and southern Virginia and will continue through the
evening.

2. Damaging winds are spreading eastward across portions of central
and eastern North Carolina, and will continue through this evening.
These winds have the potential to cause tree and structural damage.
Strong winds are also expected over portions of southeastern
Virginia and the Virginia Eastern Shore tonight as Michael becomes post-tropical.

3. Dangerous storm surge is possible tonight along the sound side of
the North Carolina Outer Banks from Ocracoke Inlet to Duck, where a
Storm Surge Watch is in effect.

FORECAST POSITIONS AND MAX WINDS

INIT 11/2100Z 36.1N 78.8W 45 KT 50 MPH...INLAND
12H 12/0600Z 38.1N 74.7W 45 KT 50 MPH...POST-TROP/EXTRATROP
24H 12/1800Z 41.2N 66.5W 60 KT 70 MPH...POST-TROP/EXTRATROP
36H 13/0600Z 44.5N 55.5W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 13/1800Z 47.0N 42.0W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 14/1800Z 48.5N 17.5W 50 KT 60 MPH...POST-TROP/EXTRATROP
96H 15/1800Z 46.5N 7.0W 30 KT 35 MPH...POST-TROP/EXTRATROP
120H 16/1800Z...DISSIPATED

$$
Forecaster Brown

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