Tropical Cyclone Discussion

302
WTPZ44 KNHC 111445
TCDEP4
 
Tropical Storm Norbert Discussion Number   8
NWS National Hurricane Center Miami FL       EP142026
500 AM HST Fri Sep 11 2026
 
Norbert continues to be defined by a shield of deep convection. The
storm's organization appears to be improving as well, with GPM
microwave imagery from around 1030 UTC suggesting that Norbert's
center of circulation is located closer to the center of
convection, rather than being displaced to the west as it was last
advisory. The latest subjective Dvorak analysis from TAFB rated
Norbert at 3.5/3.5, or an intensity of 55 kt, while objective
analyses from UW-CIMSS estimated Norbert to be between 52-61 kt.
Based on a blend of these numbers, Norbert's initial intensity has 
been increased to 55 kt.
 
The initial motion is estimated to be 275/12 kt. Norbert's westward
motion continues to be guided by a low- to mid-level high pressure
system centered over the east Pacific, just to the storm's north.
Track models are in good agreement in depicting a slight turn to the
west-northwest over the weekend, due to an upper-level low weakening
the ridge slightly, before turning toward the west-southwest early
next week as the high pressure strengthens once again. Models are
split in depicting the timing and magnitude of this more southward
turn, hindering forecast confidence beyond 72 h. The latest track
forecast is little changed from the previous advisory, with any
slight adjustments made reflecting a blend of GDMI and HCCA.
 
SHIPS guidance suggests that Norbert will remain in a favorable 
environment for strengthening through much of the forecast period. 
Global models hint at drier air moving down from the East Pacific 
high and being ingested into Norbert's west flank early next week, 
which could induce some weakening. The overall trend across 
intensity guidance is to favor slight strengthening through the 
weekend, before introducing gradual weakening starting early next 
week. The latest intensity forecast generally reflects this, but 
lies on the upper end of the guidance envelope, due to the favorable 
environment Norbert is expected to be in for at least the first half 
of the forecast period.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/1500Z 16.6N 124.7W   55 KT  65 MPH
 12H  12/0000Z 16.7N 126.3W   60 KT  70 MPH
 24H  12/1200Z 17.0N 128.4W   65 KT  75 MPH
 36H  13/0000Z 17.5N 130.4W   65 KT  75 MPH
 48H  13/1200Z 18.0N 132.3W   70 KT  80 MPH
 60H  14/0000Z 18.2N 134.3W   70 KT  80 MPH
 72H  14/1200Z 18.4N 136.4W   65 KT  75 MPH
 96H  15/1200Z 18.2N 140.7W   60 KT  70 MPH
120H  16/1200Z 16.9N 144.9W   55 KT  65 MPH