ZCZC HFOTCDCP4 ALL
TTAA00 PHFO DDHHMM
 
Hurricane Norman Discussion Number  42
NWS Central Pacific Hurricane Center Honolulu HI   EP162018
500 AM HST Fri Sep 07 2018
 
Norman continues to be torn apart by 40 to 45 kt vertical wind
shear this morning, with 1200 UTC infrared imagery showing the low
level circulation center (LLCC) becoming exposed. All remaining
deep convection has been sheared to the northwest through northeast
of the LLCC. Outflow is best to the north through northeast and
almost non-existent elsewhere. Subjective Dvorak current intensity 
estimates were 4.0/65 kt from all three analysis centers, with the 
latest ADT from UW-CIMSS at 61 kt. Given this agreement and the
continuous deterioration of this system, initial intensity is set at
65 kt for this advisory.

Initial motion is 315/08 kt. The emergence of the LLCC from beneath 
layered clouds removed all doubt concerning Norman's position and 
makes motion estimates easier. This tropical cyclone continues to 
move northwest along the western flank of a ridge and toward an 
upper trough to its north. The entire track guidance envelope 
shifted to the right, with GFS now along the right side after 
running within the left third of the envelope 12 hours ago. After a 
small shift to the left through 24 hours, along GMNI, to account
for initial motion, the forecast track was shifted significantly to
the right to stay within the guidance envelope. The current track
now lies between HWRF and TVCE ensemble guidance from 36 through
120 hours.

Norman will continue to experience 40 to 50 kt of vertical wind 
shear through 48 hours. This will continue to weaken the tropical 
cyclone rather rapidly, particularly in light of the cooler sea 
surface temperatures ahead. Norman is forecast to become a remnant 
low by day 3, following the IVCN weakening curve. However, SHIPS 
intensity guidance depicts a remnant low by day 2, so this status 
may come sooner.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/1500Z 23.0N 152.6W   65 KT  75 MPH
 12H  08/0000Z 23.8N 153.6W   55 KT  65 MPH
 24H  08/1200Z 25.1N 154.7W   45 KT  50 MPH
 36H  09/0000Z 26.5N 155.4W   40 KT  45 MPH
 48H  09/1200Z 28.3N 156.0W   35 KT  40 MPH
 72H  10/1200Z 31.5N 156.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  11/1200Z 34.5N 157.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  12/1200Z 37.8N 158.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Powell
 
NNNN