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TROPICAL STORM DARBY DISCUSSION NUMBER  55
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP052016
1100 PM HST SUN JUL 24 2016
 
Bands of heavy rain with embedded strong thunderstorms have been
developing to the north through southeast of Darby's center
over the past several hours, with some of these bands causing
significant flooding impacts over the island of Oahu.  The
subjective Dvorak intensity estimates from HFO/SAB/GTW all indicated
a current intensity of 2.0/30 kt.  However, the current intensity of
Darby will be maintained at 35 kt for this advisory due to the
strong thunderstorms leading to tropical storm conditions over areas
to the north through southeast of the center. 

The initial motion vector for this advisory 325/10 kt, with Darby
becoming increasingly shallow as it is embedded in an environment 
characterized by strong southwesterly shear.  Although SHIPS
guidance reduces the shear on days 2 and 3, Darby is not expected to
survive the trek over increasingly cooler waters, and degeneration
to a post-tropical low is expected relatively soon.  Global models
indicate Darby will track toward the northwest before weakening to a
trough by day 3, and the official forecast follows closely.  The
updated track forecast follows the trajectory of the previous
closely, except for a slight westward shift in order to come in line
with the latest GFEX guidance. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/0900Z 22.4N 159.4W   35 KT  40 MPH
 12H  25/1800Z 23.3N 160.3W   30 KT  35 MPH
 24H  26/0600Z 24.4N 161.7W   30 KT  35 MPH
 36H  26/1800Z 25.6N 163.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  27/0600Z 27.1N 164.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  28/0600Z...DISSIPATED
 
$$
Forecaster Birchard
 
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