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Tropical Depression Eighteen-E Discussion Number 13
NWS National Hurricane Center Miami FL EP182021
900 AM CST Sun Nov 07 2021
The depression's convective pattern remains quite disorganized
this morning. Although there are several blobs of convection and
areas of colder cloud tops, there is no evidence of curved banding
in both convection satellite and recent microwave data. It is
difficult to tell if the circulation has become any better defined
since the ASCAT overpass last evening. Hopefully the ASCAT
instrument will provide a better assessment of the system's
structure and strength later today. Subjective and objective Dvorak
intensity estimates are in the 30-35 kt range, and given the lack
of organization and earlier scatterometer data, the initial wind
speed is held at 30 kt.
The center of the depression has been difficult to locate this
morning, but recent fixes and continuity from the previous advisory
suggest it is moving westward or 275/12 kt. A deep-layer ridge to
the north of the depression should continue to steer it westward to
west-northwestward during the next several days. The model envelope
has trended a little farther north this cycle, but the NHC forecast
remains similar to the previous advisory, along the southern edge
of the envelope closest to the GFS, HWRF, and HMON solutions.
The depression is forecast to remain in low wind shear conditions
during the next several days, but a drier and more stable airmass
just to the north is likely to limit intensification. The NHC
forecast is unchanged from the previous advisory and still shows
the system reaching tropical storm status within the next couple
of days. By 72 hours, the vertical shear is predicted to increase
and the mid-level humidity in the surrounding environment is
forecast to decrease. These negative factors should cause
weakening and degeneration of the system to a remnant low by 96
hours, and dissipation by day 5. This is supported by the GFS and
ECMWF models which weaken the system within the ITCZ after midweek.
FORECAST POSITIONS AND MAX WINDS
INIT 07/1500Z 8.2N 101.4W 30 KT 35 MPH
12H 08/0000Z 8.7N 103.3W 30 KT 35 MPH
24H 08/1200Z 9.2N 105.7W 30 KT 35 MPH
36H 09/0000Z 9.5N 108.1W 35 KT 40 MPH
48H 09/1200Z 9.8N 110.6W 35 KT 40 MPH
60H 10/0000Z 10.1N 113.0W 35 KT 40 MPH
72H 10/1200Z 10.1N 115.4W 30 KT 35 MPH
96H 11/1200Z 10.2N 120.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 12/1200Z...DISSIPATED
$$
Forecaster Brown
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