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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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