[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 081500
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  42
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
1100 AM EDT SAT OCT 08 2016

Aircraft reconnaissance and land-based radar data indicate that the
center of circulation has crossed the coast of South Carolina near
the Cape Romain National Wildlife Refuge.

The cloud pattern associated with Matthew is beginning to acquire
some extratropical characteristics. The wind field is expanding, and
the area of heavy rains is now northwest of the center.  Data from
NOAA and Air Force reconnaissance aircraft around 1200 UTC indicated
that the surface winds have decreased to around 65 kt. (Very recent
SFMR winds of 78 kt were taken over shallow water where the
instrument is affected by shoaling and provides unreliable output).
Most of the global models, primarily the GFS and the UKMET, forecast
that Matthew will become entangled with a cold front, and the new
NHC forecast calls for Matthew to become absorbed within this
frontal system within the next couple of days.  During the next 12
to 24 hours, while the Matthew is hugging the US coast and taking on
a more extratropical structure, the tropical-storm-force winds are
expected to expand and strengthen in the western semicircle and
continue to affect portions of the coast within the warning area.

Matthew is already embedded in the mid-latitude westerly flow and is
moving toward the northeast or 050 degrees at 10 kt. The steering
pattern is forecast to persist for the next day or two, and on this
basis the NHC forecast moves the cyclone eastward until it becomes
absorbed.  Previous NHC official forecasts followed the EMCWF in
keeping the cyclone a distinct entity longer and looping it
southward, but even if this the case the system will likely be only
a broad area of low pressure.

Due to the degradation of Matthew's radar signature, the hourly
Tropical Cyclone Updates will not longer be issued.


KEY MESSAGES:

1.  As Matthew's structure changes, the system's strongest winds
will shift to the back side of the circulation. These winds will
persist over land even after the center begins to move away from the
coastline, and has also increased the threat of storm surge in
portions of the North Carolina Outer Banks.  Please see the
Prototype Storm Surge Watch/Warning Graphic for a depiction of the
areas at risk.


FORECAST POSITIONS AND MAX WINDS

INIT  08/1500Z 33.0N  79.4W   65 KT  75 MPH
 12H  09/0000Z 33.6N  78.0W   60 KT  70 MPH
 24H  09/1200Z 34.0N  75.5W   60 KT  70 MPH
 36H  10/0000Z 34.0N  73.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 48H  10/1200Z 33.0N  72.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 72H  11/1200Z...DISSIPATED

$$
Forecaster Avila
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