WTPA43 PHFO 242054
TCDCP3

TROPICAL STORM DARBY DISCUSSION NUMBER  53
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP052016
1100 AM HST SUN JUL 24 2016

Due to vertical shear affecting Darby, most of the deep convection
is mainly confined to the southeast quadrant with some isolated
thunderstorms to the northeast of the main Hawaiian Islands. The
morning mission from the 53rd Weather Reconnaissance Squadron's
WC-130J found the center of Darby to be a bit north of the previous
forecast track with maximum winds of 36 kt to the east of the
center. Based on the aircraft recon data, the initial intensity of
Darby has been maintained at 35 kt, but perhaps barely so at this
point. Additional passes through the system are ongoing and will
hopefully provide a better idea of the consistency of the current
trends.

Darby is becoming a shallow system and is moving at 315/8 kt to the
southwest of a lower and middle-level pressure ridge. The
trusted dynamical objective aids were tightly clustered showing a
northwestward track with the center of Darby passing near or over
Oahu and Kauai later today or tonight, then continuing
northwestward through 72 hours. The forecast track has been nudged
north a bit due to the shift in the initial position, but keeps
Darby moving northwestward through 72 hours.

Sea surface temperatures should be decreasing along Darby's
forecast track and vertical shear is expected to remain relatively
strong through the next couple of days. This should result in steady
weakening of the tropical cyclone. Thus, the forecast call for Darby
to remain a tropical storm through today then become a tropical
depression tonight or Monday, followed by post-tropical remnant low
status in about 72 hours. This is close to the previous forecast but
is a bit lower than intensity consensus which holds on to tropical
storm intensity a bit longer.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/2100Z 20.7N 158.0W   35 KT  40 MPH
 12H  25/0600Z 21.7N 159.1W   35 KT  40 MPH
 24H  25/1800Z 23.1N 160.4W   30 KT  35 MPH
 36H  26/0600Z 24.1N 162.1W   30 KT  35 MPH
 48H  26/1800Z 25.3N 163.8W   30 KT  35 MPH
 72H  27/1800Z 28.6N 166.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  28/1800Z 33.0N 166.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  29/1800Z...DISSIPATED
 
$$
Forecaster Kodama