Tropical Cyclone Discussion

108
WTPZ44 KNHC 131435
TCDEP4
 
Tropical Storm Norbert Discussion Number  16
NWS National Hurricane Center Miami FL       EP142026
500 AM HST Sun Sep 13 2026
 
Norbert’s overnight burst of convection has faded since the previous
advisory, however proxy-visible satellite imagery shows that a new
convective burst appears to be developing. Water vapor imagery 
shows that there is still plenty of dry air surrounding the system. 
The latest TAFB Dvorak fix came in with an intensity of 45 kt, and 
the UW-CIMSS objective intensity estimates are in the range of 
37-43 kt. Therefore the initial intensity remains at 45 kt for this 
advisory.
 
The initial motion is estimated to be 285/10 kt. The storm is
expected to move west-northwestward to westward as it moves to the
south of a low- to mid-level subtropical ridge. The track guidance
continue to show good agreement on this general heading of the 
cyclone. The current NHC track forecast has been nudged a little 
right of the previous forecast track and remains close to the 
multi-model consensus (HCCA) and the Google DeepMind (GDMI) 
ensemble mean.
 
Some fluctuations in intensity are possible in the short term as 
Norbert remains in a marginal environment. The cyclone is contending 
with mid-level dry air intrusions and light west-southwesterly 
vertical wind shear.  After 12 h, the wind shear is expected to 
increase, which should result in a generally weakening trend. Around 
60 h, the simulated GFS and ECMWF satellite imagery shows that the 
cyclone should lose organized deep convection and it is therefore 
expected to become a post-tropical remnant low and then dissipated 
around 72 h. The current NHC intensity forecast is in line with the 
latest guidance including the HCCA and GDMI. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/1500Z 18.2N 132.7W   45 KT  50 MPH
 12H  14/0000Z 18.6N 134.4W   45 KT  50 MPH
 24H  14/1200Z 19.0N 137.0W   40 KT  45 MPH
 36H  15/0000Z 19.4N 139.7W   35 KT  40 MPH
 48H  15/1200Z 19.7N 142.4W   35 KT  40 MPH
 60H  16/0000Z 19.8N 145.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  16/1200Z...DISSIPATED