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Potential Tropical Cyclone Sixteen-E Discussion Number 1
NWS National Hurricane Center Miami FL EP162023
1000 PM CDT Sat Oct 07 2023
A couple of SSMIS microwave overpasses this evening show that
the disturbance (EP99) located a couple of hundred miles south of
Acapulco, Mexico, is becoming better organized. There is evidence
of some curved banding over the southwestern portion of the
system. While the disturbance does not have enough organization to
be a classified as a tropical cyclone, it is expected to develop
into one within the next day or so, and the forecast track brings it
near the southern coast of Mexico within the next 36 to 48 hours.
Therefore, Potential Tropical Cyclone advisories are being initiated
in order to issue a Tropical Storm Watch for a portion of the
southern coast of Mexico. The initial intensity of the disturbance
is set at 25 kt, which is supported by a couple of earlier ship
observations.
Since the system is still in its formative stage, the initial motion
estimate is a somewhat uncertain 310 degrees at 6 kt. The system
is forecast to move northwestward overnight, but it should turn
north-northwestward on Sunday between a mid-level ridge to its east
and Tropical Storm Lidia to its west. This motion should bring the
center of the system near the southern coast of Mexico in about 48
hours. The GFS is much faster than the remainder of the global
model guidance and takes the center ashore in a little more than 24
hours, while the ECMWF and UKMET models are about 12 to 24 hours
slower. The NHC track forecast is near the various consensus aids,
accounting for the variations in forward speed.
The disturbance is located within a moist atmosphere and over SSTs
of 29-30 degrees C. However, the upper-level environment is not as
conducive as there is currently moderate to strong vertical wind
shear over the system. The shear is forecast to relax during the
next day or two, and this should allow the system to develop into a
tropical cyclone and strengthen into a tropical storm before it
reaches the southern coast of Mexico. The NHC intensity forecast
shows a peak that is similar to the latest HFIP corrected consensus
aid. After landfall, rapid weakening is expected, and the system
is forecast to dissipate by 72 hours.
Key Messages:
1. The disturbance is expected to become a tropical storm before it
approaches the coast of southern Mexico on Monday. A tropical storm
watch has been issued for a portion of the southern coast of Mexico.
2. Heavy rains from this system will likely produce flash and urban
flooding, along with possible mudslides in areas of higher terrain
across the states of Guerrero and Michoacan.
FORECAST POSITIONS AND MAX WINDS
INIT 08/0300Z 13.9N 100.1W 25 KT 30 MPH...POTENTIAL TROP CYCLONE
12H 08/1200Z 14.7N 100.7W 30 KT 35 MPH...TROPICAL CYCLONE
24H 09/0000Z 15.6N 101.2W 35 KT 40 MPH
36H 09/1200Z 16.4N 101.4W 40 KT 45 MPH
48H 10/0000Z 17.3N 101.4W 45 KT 50 MPH
60H 10/1200Z 18.5N 101.2W 30 KT 35 MPH...INLAND
72H 11/0000Z...DISSIPATED
$$
Forecaster Brown
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