[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 062055
TCDAT1

Tropical Storm Nate Discussion Number  10
NWS National Hurricane Center Miami FL       AL162017
400 PM CDT Fri Oct 06 2017

Satellite imagery this afternoon indicates that convection
associated with Nate is becoming better organized, with a strong
convective band now wrapping about three-quarters of the way around
the center.  Recent data from NOAA buoy 42056 near the center
suggest the central pressure has fallen to near 993 mb, and the
buoy just reported a 1-minute average wind of 49 kt.  Based on
this, the initial intensity is increased to a possibly conservative
50 kt.  The next aircraft investigating Nate is scheduled to arrive
near 22Z.

The initial motion is north-northwestward or 340/18 kt.  Nate
remains between a complex deep-layer low pressure area over the
western Gulf of Mexico and Central America and a building ridge of
high pressure over the western Atlantic.  This combination should
steer the storm quickly north-northwestward for the next 24 h or so.
After that, Nate should turn northward and northeastward as it goes
around the western edge of the ridge and recurves into the
mid-latitude westerlies.  The guidance remains in good agreement
with the direction of motion, and it has come into better agreement
on the speed.  Thus, the new forecast track is similar to, but
slightly to the west of the the previous track, and it calls for the
center of Nate to pass near or over the northeastern tip of the
Yucatan Peninsula in about 6 h, followed by landfall on the northern
Gulf Coast around the 36-h point.  It should be noted that the
ECMWF and GFS are both a little to the left of the current track.

Conditions appear favorable for continued strengthening up to
landfall on the northern Gulf Coast, and Nate is expected to make
landfall there as a hurricane.  The new intensity forecast, which is
an update of the previous one, lies near the upper edge of the
intensity guidance.  Given the current developments, there is still
a possibility of a period of rapid intensification as Nate crosses
the Gulf of Mexico.  As alternative scenarios to the actual forecast
of steady strengthening, the ECMWF forecasts no additional
strengthening as Nate crosses the Gulf of Mexico, and the GFS/UKMET
forecast little additional strengthening until the last 12 h before
landfall.


KEY MESSAGES:

1. Nate could be near hurricane intensity when it passes near or
over the Yucatan Peninsula during the next several hours bringing
direct impacts from wind, storm surge, and heavy rainfall. A
tropical storm warning and a hurricane watch are in effect for a
portion of this area, and life-threatening flash flooding is also
possible.

2. Life-threatening storm surge flooding is likely along portions of
the northern Gulf Coast, and a storm surge warning is now 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.

3. 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.

4. Nate will bring heavy rainfall of 3 to 6 inches with isolated
totals of 12 inches from the central Gulf Coast states into the
eastern Tennessee Valley and southern Appalachians through this
weekend, resulting in the possibility of flash flooding in these
areas.

5. Heavy rainfall from Nate will continue to be a threat in portions
of Central America, with life-threatening flash flooding and mud
slides possible in portions of Nicaragua, Honduras, Costa Rica,
Panama, and Belize through tonight.


FORECAST POSITIONS AND MAX WINDS

INIT  06/2100Z 20.3N  85.7W   50 KT  60 MPH
 12H  07/0600Z 23.0N  87.2W   55 KT  65 MPH
 24H  07/1800Z 26.8N  88.9W   60 KT  70 MPH
 36H  08/0600Z 29.9N  89.1W   70 KT  80 MPH
 48H  08/1800Z 33.1N  87.2W   45 KT  50 MPH...INLAND
 72H  09/1800Z 39.5N  78.5W   25 KT  30 MPH...INLAND
 96H  10/1800Z 43.5N  66.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  11/1800Z...DISSIPATED

$$
Forecaster Beven
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