ZCZC HFOTCDCP4 ALL
TTAA00 PHFO DDHHMM
 
Hurricane Norman Discussion Number  36
NWS Central Pacific Hurricane Center Honolulu HI   EP162018
500 PM HST Wed Sep 05 2018
 
It appears the 15 to 20 kt of southwesterly shear is beginning to 
impact the core of Hurricane Norman. Microwave overpasses at 2259 
and 0036 UTC appear to show the eyewall starting to break down. The 
eye has becoming indistinct, and surrounding convection has taken
on a ragged appearance in recent infrared satellite imagery as
well. Current intensity numbers from PHFO, JTWC, and SAB were all
5.5, which agree nicely with CIMSS ADT and SATCON. Thus, a current 
intensity estimate of 105 kt was used for this advisory. It should 
be noted that this is not meant to reflect intensification from the 
previous advisory, which appears to have been a bit too
conservative.

Norman looks as though it has started the anticipated
west-northwest motion. When attempting to account for trochoidal
wobbles, this new vector appears to be about 290/8. The forecast
track philosophy has not changed, with a digging trough in the
middle and upper levels north of the main Hawaiian Islands imparting
a more northwestward motion with time. The guidance spread increases
beyond 24 hours, with some of the reliable global models on the west
side of the guidance envelope. However, the consensus tracks through
120 hours, including HCCA and TVCN, continue to agree well with our
official track, so few changes were made. It should be noted that
none of the reliable guidance suggests direct impacts from Norman on
the main Hawaiian Islands. However, as the tropical cyclone will be
in our general vicinity for the next couple of days, people should
continue to monitor the progress of this system.

In addition to increasing southwesterly shear, the tropical cyclone 
is also over marginal sea surface temperatures of 26.5 to 27C.
After 48 hours, sub-26C water lies along the forecast track and
even stronger shear is anticipated. Our forecast reflects a slow 
weakening but remains near the high end of the guidance for the 
first 24 to 36 hours, then weakens Norman at a rate near the middle 
of the guidance spread afterwards, but not quite as fast as the
GFS- or ECMWF-based SHIPS indicates. Norman is forecast to become a
post-tropical remnant low in about 5 days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/0300Z 20.0N 149.2W  105 KT 120 MPH
 12H  06/1200Z 20.5N 150.3W  100 KT 115 MPH
 24H  07/0000Z 21.4N 151.4W   90 KT 105 MPH
 36H  07/1200Z 22.5N 152.4W   80 KT  90 MPH
 48H  08/0000Z 23.6N 153.4W   65 KT  75 MPH
 72H  09/0000Z 25.9N 155.4W   40 KT  45 MPH
 96H  10/0000Z 27.8N 157.4W   30 KT  35 MPH
120H  11/0000Z 29.8N 159.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster R Ballard
 
NNNN