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Hurricane Norma Discussion Number  10
NWS National Hurricane Center Miami FL       EP172023
900 PM MDT Thu Oct 19 2023

The eye of Norma is no longer evident on conventional geostationary 
satellite imagery, but could still be seen on a recent SSMI/S 
microwave pass.  Deep convection remains very strong near the 
estimated center with some cloud tops colder than -80 deg C.  A few 
convective banding features are evident over the northern portion 
of the circulation, and upper-level outflow is still strong over 
most sectors of the system.  The current intensity is set at 105 kt 
for this advisory, which is a blend of various subjective and 
objective satellite estimates.  This is in best agreement with a 
recent AI-based objective Dvorak estimate from UW-CIMSS.  

For the next couple of days, Norma's environment will be 
characterized by increasing south-southwesterly vertical wind 
shear, associated with a broad upper-level trough near the Baja 
California peninsula, along with a drier mid-level air mass.  These 
factors should cause gradual weakening while the system nears 
southern Baja California Sur, but it is likely that Norma will still 
be a hurricane when it moves near or over that area.  The official 
intensity forecast is on the higher side of the model guidance 
during the early part of the forecast period, but close to the 
corrected model consensus, HCCA at 48 hours and beyond.

Although the center fixes are a little more uncertain than earlier 
today, the initial motion does not appear to have changed much and 
is around 350/6 kt.  Over the next few days, Norma is expected to 
move between a mid-level high to its east and a trough to the 
northwest and north.  The track guidance models, especially the 
more reliable ones, have come into a little better agreement, and 
the NHC forecast track is close to the simple dynamical model 
consensus.  This is also close to the previous official forecast.

 
Key Messages:
 
1. A Hurricane Warning is in effect for the far southern portion of
the Baja California peninsula, where Norma is expected to bring
hurricane conditions on Saturday when it passes near or over the
area.

2. Heavy rains from Norma will begin to impact the far southern 
portions of California Baja Sur on late Friday, continuing through 
Sunday  This rainfall may produce flash and urban flooding, along 
with possible mudslides in areas of higher terrain.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0300Z 18.2N 108.1W  105 KT 120 MPH
 12H  20/1200Z 19.2N 108.6W  100 KT 115 MPH
 24H  21/0000Z 20.6N 109.2W   90 KT 105 MPH
 36H  21/1200Z 22.1N 109.5W   85 KT 100 MPH
 48H  22/0000Z 23.2N 109.4W   65 KT  75 MPH
 60H  22/1200Z 23.8N 109.0W   60 KT  70 MPH
 72H  23/0000Z 24.4N 108.1W   50 KT  60 MPH
 96H  24/0000Z 25.3N 106.5W   30 KT  35 MPH...INLAND
120H  25/0000Z...DISSIPATED
 
$$
Forecaster Pasch
 
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