[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 032035
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  23
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
500 PM EDT MON OCT 03 2016

Matthew's structure has not changed much today.  The most recent Air
Force Hurricane Hunter aircraft mission found peak SFMR winds of 124
kt on their last pass through the northeastern eyewall, and a peak
flight-level wind of 118 kt.  Based on a blend of these data, the
initial intensity is held at 120 kt for this advisory. The central
pressure has been steady around 940 mb for much of the day.
Matthew's satellite presentation remains impressive, with a 15 n mi
wide eye surrounded by convective tops of -80C or colder and
excellent outflow, especially poleward.  Little change in intensity
is expected during the next couple of days, with the exception of
some possible weakening due to land interaction with Haiti and
eastern Cuba.  However, there could be fluctuations in intensity due
to eyewall cycles that are difficult to predict. While Matthew is
expected to be a little weaker once it moves into the Bahamas as the
shear increases somewhat and the ocean heat content decreases a
little, it is expected to remain a dangerous hurricane through the
next 5 days, as shown by the global models. The new NHC intensity
forecast is close to or a little above the latest intensity
consensus through 4 days and is closest to the GFDL model at day 5.

Matthew is now moving a little to the east of due north, or 010/06.
The short term track forecast reasoning remains unchanged, as the
hurricane will move generally northward for the next 24 to 36 hours
around the western periphery of the Atlantic subtropical ridge.  The
new NHC track forecast during this time has been nudged eastward
toward the latest multi-model consensus aids, and continues to show
the core of the dangerous hurricane moving near or over the
southwestern peninsula of Haiti tonight and near or over eastern
Cuba on Tuesday.

At 48 hours and beyond, the GFS has trended sharply westward, and
now is in agreement with the UKMET and ECMWF in showing the western
extent of the Atlantic subtropical ridge nosing north of Matthew
across the Carolinas in 3-4 days.  This results in Matthew taking a
more northwesterly track across the Bahamas, and closer to the
Florida peninsula during this time.  The UKMET is farthest west,
with a track over the east coast of Florida and into South Carolina
in 4-5 days.  The GFS, ECMWF, and the GFDL model are a little
farther east and remain close to but offshore of Florida.  The GFDL
and GFS are close to southeastern North Carolina by day 5, while the
ECMWF is slower. The new NHC track forecast has been adjusted
significantly westward at days 3-5, and now lies near the middle of
the guidance envelope and close to the ECMWF/GFS blend.  While there
remains significant uncertainty in the track of Matthew in the long
range, the threat to Florida and the southeastern U.S. coast has
increased.

KEY MESSAGES:

1.  Matthew is likely to produce devastating impacts from storm
surge, extreme winds, heavy rains, flash floods, and/or mudslides in
portions of the watch and warning areas in Haiti, Cuba, and the
Bahamas.  Please consult statements from the meteorological services
and other government officials in those countries.

2.  Direct hurricane impacts are possible in Florida later this
week.  Tropical storm and/or hurricane watches could be issued
sometime tonight or early tomorrow for portions of the Florida
peninsula and the Florida Keys.

3.  Tropical storm or hurricane conditions could affect portions of
Georgia, South Carolina, and North Carolina later this week or this
weekend, even if the center of Matthew remains offshore.  It is too
soon to specify what, if any, direct impacts Matthew might have on
the remainder of the U.S. east coast.  At a minimum, very dangerous
beach and boating conditions are likely along much of the U.S. east
coast later this week and weekend.

FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 16.3N  74.7W  120 KT 140 MPH
 12H  04/0600Z 17.4N  74.6W  120 KT 140 MPH
 24H  04/1800Z 19.2N  74.4W  120 KT 140 MPH
 36H  05/0600Z 21.0N  74.7W  115 KT 130 MPH
 48H  05/1800Z 22.8N  75.5W  110 KT 125 MPH
 72H  06/1800Z 26.0N  78.0W  105 KT 120 MPH
 96H  07/1800Z 29.5N  79.0W  100 KT 115 MPH
120H  08/1800Z 33.0N  78.0W   90 KT 105 MPH

$$
Forecaster Brennan
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