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Tropical Depression Twenty-Three-E Discussion Number 1
NWS National Hurricane Center Miami FL EP232018
1000 AM CDT Fri Oct 19 2018
Two distinct areas of low pressure formed late yesterday within a
sprawling area of disturbed weather that stretched from Central
America westward over the eastern Pacific waters south of Mexico.
The easternmost low south of Guatemala is small and has spun up
quickly, with deep convection continuing to burst near the center of
circulation. Microwave data, first-light visible images, and
valuable radar data from Guatemala also show a tight core and
increasing convective bands. Maximum winds are set at 30 kt,
slightly above last evening's ASCAT pass and a T1.5 Dvorak
classification from TAFB, given the system's well-developed
structure.
The depression is located over warm waters (28-29 degrees Celsius)
and in a light-shear environment. These conditions should support
further strengthening, and the depression's small size may allow for
intensification higher than what is indicated by the intensity
models. For this first advisory, the NHC intensity forecast is near
the top end of the guidance envelope and levels off the maximum
winds in 3-5 days when there could be an increase in shear.
Since the low formed recently, the depression's current motion is
uncertain. However, microwave fixes indicate that it hasn't moved
much since last evening, and the initial motion estimate is slowly
west-northwestward, or 300/2 kt. A strong mid-level ridge spanning
across the Gulf of Mexico and northern Mexico should steer the
cyclone generally westward for the next 3 days or so. After day 3,
the ridge is expected to retreat eastward a bit, and the cyclone
should begin to turn northwestward between the ridge and another
low pressure system to the west. The track models are in good
agreement on this general scenario, but there is not agreement on
how close the system could get to the coast of Mexico during the
forecast period. Therefore, interests along the southern and
southwestern coast of Mexico should monitor the progress of this
system during the next few days. Regardless of how close it gets
to the coast, heavy rainfall, with possible life-threatening flash
flooding, is expected over portions of El Salvador, Guatemala, and
southeastern Mexico during the next few days.
FORECAST POSITIONS AND MAX WINDS
INIT 19/1500Z 13.3N 91.9W 30 KT 35 MPH
12H 20/0000Z 13.7N 93.2W 35 KT 40 MPH
24H 20/1200Z 13.5N 94.2W 40 KT 45 MPH
36H 21/0000Z 13.3N 94.9W 45 KT 50 MPH
48H 21/1200Z 13.3N 96.1W 50 KT 60 MPH
72H 22/1200Z 13.8N 99.5W 50 KT 60 MPH
96H 23/1200Z 16.0N 103.0W 55 KT 65 MPH
120H 24/1200Z 19.0N 105.5W 55 KT 65 MPH
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Forecaster Berg
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