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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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