[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 070857
TCDAT1

Hurricane Nate Discussion Number  12
NWS National Hurricane Center Miami FL       AL162017
400 AM CDT Sat Oct 07 2017

An Air Force reconnaissance plane investigated Nate a couple of
hours ago and measured peak flight-level winds of 89 kt at 850 mb
to the east of the center. No hurricane force winds were reported
west of the center.  The SFMR winds from that mission yielded an
initial intensity of 70 kt.  Since the plane left, the satellite
presentation has changed little, so the winds remains with the same
value in this advisory. Another reconnaissance plane is currently
approaching Nate.

The outflow is well established suggesting that the shear is low,
while the atmospheric conditions favor some additional
strengthening. On this basis, the NHC forecast calls for some slight
increase in the winds, however, the SHIPS/LGEM models forecast Nate
to be a little bit stronger just before landfall.  After landfall,
weakening is anticipated and Nate is forecast to dissipate in 96
hours or sooner.

Nate is moving rapidly toward the north-northwest at about 19 kt.
The hurricane is being steered by the flow between a large cyclonic
gyre over the southwestern Gulf of Mexico and a developing mid-level
ridge over the western Atlantic. This pattern should continue to
force Nate on a general north-northwest fast track for the next 24
hours.  After that time, the hurricane will recurve northeastward
with additional increase in forward speed as it encounters the
mid-latitude westerlies. The NHC track forecast has not changed much
from the previous one and is and is very close the HFIP corrected
consensus HCCA. This model has been very skillful this season.


KEY MESSAGES:

1. Life-threatening storm surge flooding is likely along portions
of the northern Gulf Coast, and a storm surge warning is in effect
from Morgan City, Louisiana, to the Okaloosa/Walton county line in
Florida.  Residents in these areas should heed any evacuation
instructions given by local officials.

2. A hurricane warning is in effect for portions of the northern
Gulf Coast from Louisiana to Alabama, and preparations to protect
life and property should be rushed to completion in these
areas.

3. 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.

4. Moisture from Nate interacting with a frontal zone will also
bring 2 to 4 inches with isolated totals of 6 inches across the
Ohio Valley into the central Appalachians Sunday into Monday,
which will also increase the risk for flash flooding across these
locations.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0900Z 24.5N  87.0W   70 KT  80 MPH
 12H  07/1800Z 27.3N  88.3W   75 KT  85 MPH
 24H  08/0600Z 30.4N  88.8W   80 KT  90 MPH
 36H  08/1800Z 33.8N  86.6W   40 KT  45 MPH...INLAND
 48H  09/0600Z 37.0N  83.0W   30 KT  35 MPH...INLAND
 72H  10/0600Z 43.0N  70.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  11/0600Z...DISSIPATED

$$
Forecaster Avila
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