241
WTPZ44 KNHC 120250
TCDEP4

Tropical Storm Norbert Discussion Number  10
NWS National Hurricane Center Miami FL       EP142026
500 PM HST Fri Sep 11 2026

Satellite imagery indicates that the convective organization
associated with Norbert has changed little over the past several
hours. A well-defined curved band of deep convection continues to
wrap into the circulation around the western semicircle from the
north, although cloud-top temperatures within the band have warmed
slightly during the past few hours. The latest subjective Dvorak
intensity estimate from TAFB maintains T3.5/55 kt, which harmonizes
well with the objective intensity estimates from UW-CIMSS ranging
between 45 and 55 kt. Given these data and only modest changes in
the convective structure, the initial intensity is held at 55 kt.

The initial motion is west-northwestward, or 285/10 kt. This general
westward to west-northwestward motion is expected to persist through
the weekend as a low- to mid-level subtropical ridge remains
positioned north of the cyclone. Thereafter, confidence on Norbert`s
general motion is reduced as track models diverge significantly, as
the evolution of the mid-level ridge plays a vital role in the track
forecast over the next several days. The GFS shows the ridge
shifting eastward, causing Norbert to generally prevail westward,
while remaining on the north side of the guidance envelope. On the
other hand, the ECMWF showcases the aforementioned ridge building
southward, steering Norbert more southwestward. The consensus aids
sit snug in between these two solutions. The NHC track forecast
sides largely with the previous forecast, which lies near the Google
DeepMind ensemble mean.

Environmental conditions appear favorable for some strengthening,
and Norbert is forecast to become a hurricane within the next 24 h.
Thereafter, Norbert`s intensity is expected to remain relatively
consistent, shuffling 5 to 10 kt difference throughout the forecast
period. This will depend ultimately on the track, as discussed
above. A more northward track, more in line with the GFS, would find
Norbert in a less favorable environment, where increasing vertical
shear would weaken the system considerably. Conversely, the more
southern track similar to the ECMWF, would bring Norbert into a more
favorable environment with less vertical wind shear, allowing
Norbert to potentially strengthen. Given the competing scenarios
thereafter, little change has been made to the previous intensity
forecast, with some weakening still indicated early next week. The
NHC intensity forecast is generally an update to the previous
advisory.


FORECAST POSITIONS AND MAX WINDS

INIT  12/0300Z 17.2N 126.6W   55 KT  65 MPH
 12H  12/1200Z 17.4N 127.9W   60 KT  70 MPH
 24H  13/0000Z 17.8N 129.8W   65 KT  75 MPH
 36H  13/1200Z 18.2N 131.5W   65 KT  75 MPH
 48H  14/0000Z 18.5N 133.3W   65 KT  75 MPH
 60H  14/1200Z 18.7N 135.5W   55 KT  65 MPH
 72H  15/0000Z 18.6N 137.3W   55 KT  65 MPH
 96H  16/0000Z 18.0N 141.9W   55 KT  65 MPH
120H  17/0000Z 16.3N 146.1W   55 KT  65 MPH

$$
Forecaster Pierce/Gibbs