000
WTNT44 KNHC 281502
TCDAT4

TROPICAL STORM MATTHEW DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
1100 AM AST WED SEP 28 2016

Surface observations and data from an Air Force Reserve
reconnaissance aircraft indicate that the tropical wave passing
through the Windward Islands has acquired a closed circulation.  The
aircraft found peak flight-level winds of 64 kt, and SFMR surface
winds of around 50 kt over the northern portion of the circulation.
As a result, advisories are being initiated on a 50-kt tropical
storm. The current lack of inner core structure suggests that
further strengthening should be limited today, but environmental
conditions consisting of warm water and low shear ahead of Matthew
favor intensification throughout the remainder of the forecast
period. The NHC intensity forecast is more conservative than the
statistical guidance, but follows the trends of the global models
in deepening the system.

Since the center has very recently formed, the initial motion
estimate is a highly uncertain 275/18 kt.  A strong deep-layer ridge
over the western Atlantic should steer Matthew westward across the
eastern Caribbean during the next few days, and the track guidance
is tightly clustered through 72 hours.  After that time, the
tropical cyclone will be approaching the western portion of the
ridge and a northwestward turn is expected, although there are
significant differences among the track models as to when the turn
takes place and how sharp it will be.  The GFS takes the cyclone
northwestward much faster than the ECMWF with more troughing
developing over the eastern Gulf of Mexico.  For now, the NHC track
lies near a consensus of the faster GFS and slower ECMWF.


FORECAST POSITIONS AND MAX WINDS

INIT  28/1500Z 13.4N  60.7W   50 KT  60 MPH
 12H  29/0000Z 13.6N  63.2W   50 KT  60 MPH
 24H  29/1200Z 13.9N  66.4W   55 KT  65 MPH
 36H  30/0000Z 13.9N  69.0W   60 KT  70 MPH
 48H  30/1200Z 13.8N  71.2W   65 KT  75 MPH
 72H  01/1200Z 13.5N  74.2W   70 KT  80 MPH
 96H  02/1200Z 14.8N  75.6W   80 KT  90 MPH
120H  03/1200Z 17.5N  76.5W   90 KT 105 MPH

$$
Forecaster Brown