Tropical Cyclone Discussion

984
WTPZ44 KNHC 130248
TCDEP4
 
Tropical Storm Norbert Discussion Number  14
NWS National Hurricane Center Miami FL       EP142026
500 PM HST Sat Sep 12 2026
 
Satellite imagery indicates that Norbert's convective organization 
has degraded during the past several hours. The convective mass over 
and north of the circulation center has diminished in coverage, with 
cloud-top temperatures also warming. This appears to be due, at 
least in part, to some mid-level dry air becoming entrained into the 
circulation along with some southwesterly vertical wind shear. An 
earlier scatterometer pass showed an asymmetric system with peak 
winds just above 40 kt located over the northern semicircle. The 
subjective Dvorak intensity estimate from TAFB and objective 
estimates from UW-CIMSS remain in decent agreement, ranging from 35 
to 50 kt. Given these data and the decreased organization, the 
initial intensity is lowered to 40 kt.

Norbert's initial motion is estimated to be westward, or 280/10 kt. 
The storm remains positioned south of a subtropical ridge extending 
westward from northern Mexico, which should steer Norbert on a 
general west-northwestward to westward track for the remainder of 
the forecast period. The track guidance remains in fairly good 
agreement, and the NHC track forecast is largely unchanged, 
reflecting a blend of the previous forecast and the latest 
multi-model consensus (HCCA) and Google DeepMind ensemble, which lie 
slightly north of the previous track.

The track will bring the cyclone deeper into a hostile environment 
dominated by strong westerly vertical wind shear and dry mid-level 
air. These environmental conditions will induce a steady weakening 
trend by 36 h. Model guidance unanimously reflects this hostile 
setup showing Norbert opening into a trough of low pressure east of 
Hawaii by middle portion of next week. Consequently, the updated NHC 
intensity forecast accelerates the decay timeline, degenerating 
Norbert to a remnant low by 72 h and dissipating it by 96 h.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/0300Z 17.9N 130.5W   40 KT  45 MPH
 12H  13/1200Z 18.3N 132.0W   40 KT  45 MPH
 24H  14/0000Z 18.7N 134.2W   40 KT  45 MPH
 36H  14/1200Z 19.1N 136.6W   35 KT  40 MPH
 48H  15/0000Z 19.3N 139.4W   35 KT  40 MPH
 60H  15/1200Z 19.4N 142.0W   35 KT  40 MPH
 72H  16/0000Z 19.3N 144.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  17/0000Z...DISSIPATED