Tropical Storm GAMMA Advisory 10月4日

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Tropical Storm Gamma Discussion Number   6
NWS National Hurricane Center Miami FL       AL252020
400 PM CDT Sat Oct 03 2020

Surface observations from the Yucatan Peninsula along with
high-resolution visible satellite imagery indicated that the center
of Gamma made landfall in the vicinity of Tulum, Mexico, shortly
before 1700 UTC.  Earlier aircraft observations and pressure
measurements from Tulum showed that the system was very near
hurricane strength when it made landfall.  A ragged eye appeared in
the visible images shortly after the center crossed the coast, but
that feature has since become obscured.  Since Gamma has likely
been slowly weakening while moving over land, the current intensity
has been set to 55 kt.  Continued gradual weakening is likely into
Sunday while the center either moves over land or interacts with
nearby land.  Some re-strengthening is expected to begin by
Monday, but the numerical guidance is not very enthusiastic about
intensification over the Gulf, probably due to the combination of
drier air and the interaction with another low pressure system to
the east.  The official intensity forecast is not much different
from the model consensus.

Gamma has been moving northwestward, but it is expected to turn
north-northwestward while moving near and into a weakness in the
subtropical ridge over the next day or so.  The global models
predict that a trough to the north of the tropical cyclone will
lift northeastward and bypass Gamma.  In a couple of days, a ridge
is forecast to build back, albeit weakly, across the Gulf of
Mexico.  This is expected to cause the system to turn westward to
southwestward over the latter part of the forecast period.  The
more reliable global models show the system meandering over the
southern Bay of Campeche in 4 to 5 days, and so does the official
forecast.


KEY MESSAGES:

1. Gamma is expected to produce heavy rainfall for several days over
portions of southeastern Mexico, the Yucatan Peninsula, Central
America, and far western Cuba.  This rainfall could result in
life-threatening flash flooding and mudslides, particularly in the
mountainous regions of southeastern Mexico and Central America.

2. Even though Gamma has moved inland, tropical storm conditions
will continue along the east coast of the Yucatan Peninsula through
this evening and are expected to spread along the north coast within
the Tropical Storm Warning area tonight and on Sunday.


FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 20.7N  87.7W   55 KT  65 MPH...INLAND
 12H  04/0600Z 21.3N  88.0W   45 KT  50 MPH...INLAND
 24H  04/1800Z 22.0N  88.2W   40 KT  45 MPH...OVER WATER
 36H  05/0600Z 22.1N  88.4W   40 KT  45 MPH
 48H  05/1800Z 22.0N  89.1W   45 KT  50 MPH
 60H  06/0600Z 21.6N  90.4W   50 KT  60 MPH
 72H  06/1800Z 21.0N  91.5W   50 KT  60 MPH
 96H  07/1800Z 20.0N  92.0W   45 KT  50 MPH
120H  08/1800Z 20.0N  93.0W   40 KT  45 MPH

$$
Forecaster Pasch