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Tropical Depression Norbert Discussion Number  15
NWS National Hurricane Center Miami FL       EP192020
300 AM MDT Fri Oct 09 2020
 
Norbert is clearly struggling to remain a tropical depression. The 
low-level center is exposed in recent satellite imagery, likely due 
to a combination of east-southeasterly vertical wind shear and dry 
mid-level air in the surrounding environment. The nearest deep 
convection is located roughly 50 miles south of the center, and it 
is very poorly organized. Unfortunately, overnight ASCAT passes 
missed the center of Norbert, but a partial overpass of the eastern 
semicircle revealed 20 kt winds. A blend of the UW-CIMSS objective 
estimate and the TAFB subjective Dvorak estimate supports an 
intensity of 25 kt, which may be generous given the lack of 
sustained convection near the cyclone's center.

Vertical wind shear is taking its toll on Norbert, and the latest 
SHIPS guidance suggests the deep-layer shear will increase over the 
next 24-48 h. Thus, Norbert is unlikely to survive the five-day 
forecast period. If new convection doesn't develop soon, it could 
degenerate into a remnant low as early as today. The latest NHC 
forecast explicitly calls for dissipation by 72 h. Norbert is 
starting to drift northwestward, and this general motion should 
continue over the next couple of days as a weak mid-level ridge 
builds to the northeast of the depression. The NHC track forecast 
closely follows the consensus aids and remains very close to the 
previous forecast.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  09/0900Z 13.2N 106.0W   25 KT  30 MPH
 12H  09/1800Z 13.4N 106.3W   25 KT  30 MPH
 24H  10/0600Z 13.9N 106.9W   25 KT  30 MPH
 36H  10/1800Z 14.4N 107.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  11/0600Z 14.7N 107.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  11/1800Z 14.9N 107.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  12/0600Z...DISSIPATED
 
$$
Forecaster Reinhart/Zelinsky
 
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