[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 010847
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
500 AM EDT SAT OCT 01 2016

Matthew has changed little in organization since the past advisory,
with a small eye surrounded by a central dense overcast featuring
cloud tops colder than -80C.  The eye has become a little less
distinct, suggesting at least that the hurricane is no longer
intensifying.  In addition, the raw intensity estimates from the
CIMSS ADT technique are slightly lower than they were six hours
ago.  Based on these trends, the initial intensity is reduced to
135 kt. An Air Force Reserve Hurricane Hunter aircraft is scheduled
to reach Matthew near 1200 UTC.

The initial motion is now 270/6.  Matthew remains south of a low-
to mid-level ridge over the western Atlantic.  The dynamical models
forecast this ridge to weaken over the next 72 hours as a mid- to
upper-level trough develops over the Gulf of Mexico.  This
evolution should cause Matthew to turn northwestward after 24 hours
and northward by 48-72 hours.  The guidance generally agrees with
this scenario.  However, there is a spread between the GFS forecast
of landfall in Jamaica and eastern Cuba and the ECMWF forecast
landfall in southwestern Haiti.  The guidance becomes more divergent
after 72 hours.  The GFS shows a turn toward the north-northwest,
which brings the center closer to the northwestern Bahamas and
Florida. This model is near the western edge of the guidance
envelope.  The ECMWF is near the eastern edge of the guidance
envelope and shows the center east of the Bahamas by 120 hours.
Adding to the uncertainty is the eastward shift of the Canadian
model since its previous run.  Given the uncertainty, the 96 and 120
hour forecast points are changed only slightly from the previous
forecast.  This part of the forecast track lies to the east of the
GFS, but to the west of the Canadian, ECMWF, and NAVGEM models.  It
is also a little to the west of the various consensus models.

Matthew should experience significant shear for the next 24 hours or
so, as water vapor imagery shows westerly flow blowing into the
hurricane underneath the impressive outflow pattern.  This should
cause some weakening.  After that time, the dynamical models suggest
the shear should decrease, which should allow Matthew to at least
maintain its intensity.  The new intensity forecast shows a
slightly weaker intensity than the previous advisory through 72
hours based mainly on current trends.  Subsequently, the hurricane
is likely to interact with the land masses of Jamaica, Cuba, and
Hispaniola, leading to some weakening and disruption of the
structure.  Between this and uncertainty about how much shear
Matthew will encounter north of Cuba, the new forecast shows only
modest strengthening after Matthew reaches the Atlantic north of
Cuba.  There is also the possibility of fluctuations in intensity
caused by eyewall replacement cycles at any time during the forecast
period.

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  01/0900Z 13.3N  72.8W  135 KT 155 MPH
 12H  01/1800Z 13.3N  73.6W  130 KT 150 MPH
 24H  02/0600Z 13.8N  74.5W  120 KT 140 MPH
 36H  02/1800Z 14.9N  75.1W  110 KT 125 MPH
 48H  03/0600Z 16.2N  75.7W  110 KT 125 MPH
 72H  04/0600Z 19.5N  76.0W  110 KT 125 MPH
 96H  05/0600Z 23.0N  76.0W   90 KT 105 MPH
120H  06/0600Z 26.0N  76.5W   95 KT 110 MPH

$$
Forecaster Beven
This weather bulletin was brought to you by:
www.nashvilleweather.net