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Hurricane Nate Discussion Number  15
NWS National Hurricane Center Miami FL       AL162017
1000 PM CDT Sat Oct 07 2017

A ragged central dense overcast persists over Nate's center, but
radar trends have shown all of the deep convection migrating to the
north and northeast of the center, likely due to increasing
south-southwesterly shear.  Still, the northern eyewall, which will
be moving onshore the Mississippi coast soon, remains quite
vigorous.  An Air Force Hurricane Hunter aircraft recently measured
a maximum 850-mb flight-level wind of 89 kt and some SFMR values
around 70 kt.  Although the SFMR could be affected by wave shoaling
in this case, the data as a whole appear to support an initial
intensity of 75 kt.  Nate's central pressure has been rising
slowly, with the latest report from the plane being 984 mb.

Nate has turned northward and slowed down a bit with an initial
motion of 360/17 kt.  On this course, the hurricane is expected to
make a second landfall along the Mississippi coast within the next
hour or two.  After landfall, Nate should turn gradually toward the
northeast and accelerate again during the next day or two while it
moves between a large mid-level high off the southeastern U.S. coast
and a large trough digging into the central U.S.  This steering
pattern will take Nate across the Deep South, Tennessee Valley, and
central Appalachian Mountains during the next couple of days.  The
new NHC track forecast is unchanged from the previous one.

With landfall imminent, no changes in intensity are expected before
that time.  After landfall, land and increasing shear should
contribute to fast weakening, and Nate is expected to become a
tropical storm in 6-12 hours and then weaken to a tropical
depression by 36 hours.  Nate is likely to become a remnant low by
48 hours, and the global models suggest that the cyclone will be
absorbed by another low or cold front by 72 hours.  That scenario
is now reflected in the NHC forecast.


KEY MESSAGES:

1. Nate is expected to bring life-threatening storm surge flooding
near and well east of where the center makes landfall, and a storm
surge warning is in effect from the mouth of the Mississippi River
to the Okaloosa/Walton county line in Florida.  Maximum flooding of
7 to 11 feet above ground level is expected along the Mississippi
coast within the next several hours.

2. Hurricane conditions are spreading onshore along the coasts of
Mississippi and Alabama, where a hurricane warning is in effect.
The strongest winds are expected to occur primarily to the east of
the track of the center.

3. Nate's fast forward speed after landfall will bring
tropical-storm-force winds well inland across portions of the
southeastern U.S.  Tropical storm watches and warnings are in effect
for portions of southeastern Mississippi, much of Alabama, and
western Georgia.

4. Nate will bring heavy rainfall of 3 to 6 inches with isolated
totals of 10 inches east of the Mississippi River from the central
Gulf Coast into the Deep South, eastern Tennessee Valley, and
southern Appalachians through Monday, resulting in the potential for
flash flooding in these areas.

5. Moisture from Nate interacting with a frontal zone will also
bring 2 to 5 inches of rain with isolated totals of 7 inches across
the Ohio Valley and central Appalachians Sunday and Monday, which
will increase the risk for flash flooding across these locations.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 29.9N  89.1W   75 KT  85 MPH
 12H  08/1200Z 32.1N  88.2W   50 KT  60 MPH...INLAND
 24H  09/0000Z 35.7N  85.3W   35 KT  40 MPH...INLAND
 36H  09/1200Z 39.3N  80.2W   25 KT  30 MPH...INLAND
 48H  10/0000Z 42.1N  73.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  11/0000Z...DISSIPATED

$$
Forecaster Berg

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