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Tropical Storm Norbert Discussion Number  22
NWS National Hurricane Center Miami FL       EP192020
300 AM MDT Wed Oct 14 2020

Norbert continues to produce a concentrated area of deep convection, 
but it has been very difficult pinpointing the exact location of the 
center overnight.  Earlier ASCAT data and an 0152 UTC SSMIS 
microwave overpass suggests that the center could be a little north 
of the previous estimates, but overnight shortwave infrared imagery 
and TAFB and SAB fixes still place it closer to the southern portion 
of the convective mass.  The advisory position is a compromise 
between the various estimates, but leans toward the previous track 
out of respect for continuity.  Dvorak estimates from TAFB and SAB 
support an intensity of 35 kt, which is used as the initial wind 
speed for this advisory.  The earlier ASCAT overpass revealed some 
slightly stronger wind vectors, but these appear to have been rain 
inflated.   

The initial motion estimate is a somewhat uncertain 325/13 kt.  
Norbert is moving northwestward between a mid-level ridge over 
northern Mexico and a mid- to upper-level low to its northwest. This 
general heading should continue over the next 24 to 36 hours with 
some reduction in forward speed as Norbert begins to weaken and is 
steered by the weaker low-level flow.  The dynamical models are 
in general agreement, but there are differences in how fast and far 
north Norbert will move.  The models that maintain a deeper cyclone 
depict a more poleward motion.  The NHC track leans toward the 
southern solutions by 24 hours since Norbert is likely to weaken and 
become a more vertically shallow system by that time. 

Norbert only has a short window of opportunity in which to 
strengthen this morning.  After that time, increasing southwesterly 
shear and cooler sea surface temperatures should begin to weaken 
the tropical storm.  Norbert is likely to become a remnant low in 
24 to 36 hours as it encounters sea surface temperatures below 26C, 
moderate to strong shear, and a more stable atmosphere.  The global 
models indicate that the low will dissipate within a couple of 
days, and the NHC forecast follows suit. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  14/0900Z 22.1N 113.3W   35 KT  40 MPH
 12H  14/1800Z 23.5N 114.3W   35 KT  40 MPH
 24H  15/0600Z 24.9N 115.2W   30 KT  35 MPH
 36H  15/1800Z 26.0N 115.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  16/0600Z...DISSIPATED
 
$$
Forecaster Brown
 
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