618
WTPZ44 KNHC 102046
TCDEP4

Tropical Storm Norbert Discussion Number   5
NWS National Hurricane Center Miami FL       EP142026
200 PM PDT Thu Sep 10 2026

Norbert`s structure can be described as a shear pattern, with the
low-level center near the western edge of the main convective area,
which has persisted for a while with very cold cloud tops.  The
TAFB intensity estimate is still 35 kt, but the objective estimates
have creeped up slightly, now in the 37-42 kt range.  Based on
those estimates, and the persistent nature of the deep convection,
the initial intensity estimate has been increased to 40 kt.

The tropical storm is moving westward, or 270/12 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 slightly faster toward the west than the previous
official forecast and closely follows the latest HFIP Corrected
Consensus model (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 24 hours, and SHIPS guidance forecasts
mid-level relative humidity values between 60 and 70 percent, which
are sufficiently moist enough for strengthening.  Most of the model
guidance does not show a large amount of strengthening and keeps
Norbert at tropical storm strength through the next 5 days. The
Google DeepMind Ensemble Mean, HCCA, and COAMPS-TC models peak
Norbert as a Category 1 hurricane in about 3 days before bringing it
back down to tropical storm strength by day 4 with continued
weakening into day 5.  The new NHC forecast brings Norbert up to 65
kt by day 3, following the above models, and is higher than all of
the available intensity guidance at days 4 and 5.  Given the spread
in the guidance, the confidence in the intensity forecast is below
average.

FORECAST POSITIONS AND MAX WINDS

INIT  10/2100Z 16.5N 120.5W   40 KT  45 MPH
 12H  11/0600Z 16.5N 122.5W   45 KT  50 MPH
 24H  11/1800Z 16.5N 124.9W   50 KT  60 MPH
 36H  12/0600Z 16.6N 127.1W   55 KT  65 MPH
 48H  12/1800Z 17.0N 129.0W   60 KT  70 MPH
 60H  13/0600Z 17.6N 130.7W   60 KT  70 MPH
 72H  13/1800Z 18.0N 132.4W   65 KT  75 MPH
 96H  14/1800Z 18.4N 136.1W   60 KT  70 MPH
120H  15/1800Z 18.3N 139.7W   60 KT  70 MPH

$$
Forecaster Hagen