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Tropical Depression Norbert Discussion Number  11
NWS National Hurricane Center Miami FL       EP192020
300 AM MDT Thu Oct 08 2020
 
Norbert was very close to becoming a remnant low overnight. A recent 
burst of deep convection to the southeast of the partially exposed 
low-level center was sufficient to keep Norbert as a tropical 
depression for this advisory. Water vapor imagery indicates the 
depression is still battling dry mid-level air on the northern 
periphery of the circulation. The initial intensity has been lowered 
to 25 kt based on a 04 UTC ASCAT-B overpass that showed max winds of 
25 kt in the southwest quadrant of Norbert.  
 
Norbert is presently drifting east-southeastward under weak 
steering currents, and the cyclone may continue meandering 
erratically for the next 6-12 h. Then, Norbert is forecast to move 
slowly west-southwestward or westward through 48 h. Thereafter, a 
mid-level ridge is expected to build to the north and northeast of 
Norbert, which should steer the system northwestward at a slightly 
faster speed. The NHC forecast track is shifted slightly to the 
right of the previous one based on the guidance consensus aids 
including TVCE and HCCA.

Although drier mid-level air continues to impinge on the northern 
side of Norbert's circulation, the depression remains in an 
otherwise favorable environment of high oceanic heat content and 
light vertical wind shear. If Norbert can survive the slight 
increase in deep-layer shear depicted by the SHIPS guidance during 
the next 24 h, improving environmental conditions thereafter could 
allow Norbert to at least remain a depression for several days. 
Alternatively, moderate shear and additional dry air intrusions 
could cause Norbert to degenerate into a remnant low at almost 
any time. The NHC intensity forecast assumes the first scenario and 
keeps Norbert as a 25-30 kt depression for the next several days. By 
96-120 h, GFS simulated satellite imagery suggests the cyclone will 
be devoid of convection as it moves into a drier mid-level 
environment. Thus, the official forecast depicts a transition to 
remnant low status by day 4.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/0900Z 13.2N 106.3W   25 KT  30 MPH
 12H  08/1800Z 13.0N 106.2W   25 KT  30 MPH
 24H  09/0600Z 13.0N 106.5W   25 KT  30 MPH
 36H  09/1800Z 13.2N 107.0W   30 KT  35 MPH
 48H  10/0600Z 13.5N 107.6W   30 KT  35 MPH
 60H  10/1800Z 14.4N 108.2W   30 KT  35 MPH
 72H  11/0600Z 15.3N 108.6W   30 KT  35 MPH
 96H  12/0600Z 16.0N 109.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  13/0600Z 16.5N 110.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Reinhart/Zelinsky
 
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