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Tropical Depression NORBERT

Tropical Depression Norbert Discussion Number   9
NWS National Hurricane Center Miami FL       EP192020
300 PM MDT Wed Oct 07 2020

Convection has decreased in association with Norbert since the last 
advisory, with the system now comprised of a mostly-exposed swirl 
of low-level clouds. Based on the weakened cloud pattern, the 
initial intensity is reduced to 30 kt and Norbert is downgraded to 
a depression.

Daytime visible imagery shows that Norbert is south of the 
previous advisory location, and the initial motion is a somewhat 
uncertain 180/2.  Little motion is expected during the next 12 h 
or so as the cyclone is in an area of weak steering currents.  A 
west-southwestward drift is forecast from 12-36 h.  This will be 
followed by a slow motion toward the west-northwest or northwest 
for the remainder of the forecast period as a mid-level ridge 
builds to the north and northeast of Norbert.  The forecast guidance 
has shifted to the right at 96 and 120 h, so the new forecast track 
is shifted in that direction as well.  Otherwise, the new forecast, 
which lies near the various consensus models, has only slight 
changes since the previous advisory.

While Norbert is seemingly in a favorable environment of light 
vertical wind shear over warm water, none of the intensity guidance 
calls for significant strengthening.  Indeed, the GFS and ECMWF 
models call for the system to dissipate before 120 h, possibly due 
to dry air intrusions.  Given the favorable shear and sea surface 
temperatures, the official intensity forecast calls for the system 
to survive for 5 days with little change in strength in overall 
agreement with the intensity guidance. It should be noted that if 
any strong convective bursts occur, these could cause the system to 
strengthen just the little bit it needs to regain tropical storm 

INIT  07/2100Z 13.4N 107.1W   30 KT  35 MPH
 12H  08/0600Z 13.4N 107.1W   30 KT  35 MPH
 24H  08/1800Z 13.3N 107.4W   30 KT  35 MPH
 36H  09/0600Z 13.1N 107.8W   30 KT  35 MPH
 48H  09/1800Z 13.1N 108.2W   30 KT  35 MPH
 60H  10/0600Z 13.8N 108.8W   30 KT  35 MPH
 72H  10/1800Z 14.7N 109.6W   30 KT  35 MPH
 96H  11/1800Z 16.5N 111.0W   30 KT  35 MPH
120H  12/1800Z 18.0N 112.5W   30 KT  35 MPH
Forecaster Beven