000
WTPZ44 KNHC 101440
TCDEP4
 
Tropical Storm Norbert Discussion Number   4
NWS National Hurricane Center Miami FL       EP142026
800 AM PDT Thu Sep 10 2026

An AMSR-3 microwave pass over Norbert and GOES-West Infrared 
satellite imagery indicate that the low-level center of Norbert is 
underneath the western side of main burst of convection associated 
with Norbert's developing core.  Moderate westerly wind shear is 
having a significant affect on the cyclone by pushing the majority 
of the convection to the east of the low-level center.  Given that 
the center is underneath the convection, gradual intensification 
seems possible in the short term.  The latest subjective Dvorak 
classification from TAFB is T2.5/35 kt, and recent objective 
intensity estimates from UW-CIMSS range from 35-40 kt. The initial 
intensity is held at 35 kt.

The initial motion estimate is westward, or 275/12 kt.  A 
well-established mid-level ridge to the north of Norbert should keep 
the cyclone moving in a direction between westward and 
west-northwestward for the next several days.  The NHC track 
forecast is similar to the previous one, and lies close to the HCCA.

The sheared structure of Norbert and the proximity of drier air to 
the west of the system suggests that only modest near-term 
strengthening should be expected. However, the shear is forecast to 
weaken over the next few days while the system moves into a 
sufficiently moist environment over waters near 28C.  Despite these 
seemingly favorable conditions, there are mixed signals in the 
guidance regarding how much strengthening may occur.  There is also 
a large spread in some of the ensemble intensity guidance.  For 
example, the Google DeepMind ensemble has a spread at day 4 that 
ranges from 30 to 120 kt.  The HAFS-A keeps it a tropical storm 
through the forecast period.  The HAFS-B briefly makes it a category 
1 hurricane within the next 60 hours before weakening the system 
back to a low-end tropical storm by day 4-5.  The NHC intensity 
forecast is similar to the previous one, showing a slightly faster 
intensification in the first 48 hours, but then a slower rate of 
strengthening thereafter.  The NHC intensity forecast still lies on 
the higher end of the guidance envelope and calls for Norbert to 
reach hurricane strength by early next week.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  10/1500Z 16.5N 119.3W   35 KT  40 MPH
 12H  11/0000Z 16.5N 121.2W   40 KT  45 MPH
 24H  11/1200Z 16.5N 123.7W   45 KT  50 MPH
 36H  12/0000Z 16.6N 125.9W   50 KT  60 MPH
 48H  12/1200Z 17.0N 127.9W   55 KT  65 MPH
 60H  13/0000Z 17.4N 129.7W   55 KT  65 MPH
 72H  13/1200Z 17.9N 131.4W   60 KT  70 MPH
 96H  14/1200Z 18.4N 134.7W   65 KT  75 MPH
120H  15/1200Z 18.3N 138.2W   65 KT  75 MPH
 
$$
Forecaster Hagen