[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 011453
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
1100 AM EDT SAT OCT 01 2016

The eye of Matthew has shrunk and become less distinct in
geostationary imagery during the past few hours.  Data from an Air
Force Reserve Hurricane Hunter aircraft show a very sharp wind
profile near the center and a radius of maximum winds of 7 n mi. The
central pressure has risen a little, to 947 mb on the last center
fix.  The highest SFMR wind sampled by the aircraft was 118 kt, so
the initial intensity is conservatively lowered to 125 kt for this
advisory.  Its possible that an eyewall replacement cycle has begun,
but there is not much evidence of a secondary wind maximum in the
aircraft data yet, and we haven't had any recent microwave imagery
to look at the inner-core structure.

Gradual weakening is expected in the next 24 hours, in agreement
with all of the guidance, but Matthew is expected to remain a
powerful hurricane until it until interacts with the land masses of
Jamaica, Hispaniola, and Cuba in 2-3 days.  After that time,
conditions appear conducive for restrengthening once Matthew moves
into the Bahamas late in the forecast period.  Note that there will
likely be short-term fluctuations in intensity due to possible
eyewall replacement cycles that are not shown here.

Matthew has been moving westward at around 5 kt under the influence
of a mid-level ridge centered near Bermuda.  This ridge is forecast
to gradually weaken and shift eastward, which should allow Matthew
to turn northward while it moves into a weakness in the ridge during
the forecast period.  The track model guidance is in generally good
agreement on this scenario through 48 hours, and during that time
the new NHC forecast has been shifted a little to the right toward
the latest consensus aids, but remains to their left and lies near
the latest GFS track.

Late in the period the track model spread increases, with the ECMWF
on the right and the GFS well to the left.  The evolution of the
western Atlantic subtropical ridge late in the period appears to be
sensitive to the track and strength of the mid/upper-level low
currently centered over the Ohio Valley.  The ECMWF shows a weaker
ridge, which allows Matthew to move farther east, while the GFS has
a stronger ridge and takes Matthew more north-northwestward.  Given
the uncertainty and variability seen in the handling of these
features from cycle to cycle, the NHC forecast continues to lie in
between the two scenarios, and maintains continuity with the
previous official forecast.  The new NHC track is well east of the
latest GFS by day 5, but lies west of the consensus aids.  Needless
to say, confidence in the details of the track forecast at days 4
and 5 is quite low.

It is important to remind users that average NHC track forecast
errors are around 175 miles at day 4 and 230 miles at day 5.
Therefore, it is too soon to rule out possible hurricane impacts
from Matthew in Florida.

FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 13.4N  73.4W  125 KT 145 MPH
 12H  02/0000Z 13.6N  73.9W  120 KT 140 MPH
 24H  02/1200Z 14.5N  74.6W  115 KT 130 MPH
 36H  03/0000Z 15.7N  75.2W  110 KT 125 MPH
 48H  03/1200Z 17.1N  75.5W  110 KT 125 MPH
 72H  04/1200Z 20.5N  75.5W   95 KT 110 MPH...INLAND
 96H  05/1200Z 24.0N  76.0W   95 KT 110 MPH...OVER WATER
120H  06/1200Z 26.5N  76.5W  100 KT 115 MPH

$$
Forecaster Brennan
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