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
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
$$
Forecaster Birchard
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP052016
1100 PM HST SUN JUL 24 2016
Bands of heavy rain with embedded strong thunderstorms have been
developing to the north through southeast of Darby's center
over the past several hours, with some of these bands causing
significant flooding impacts over the island of Oahu. The
subjective Dvorak intensity estimates from HFO/SAB/GTW all indicated
a current intensity of 2.0/30 kt. However, the current intensity
will be maintained at 35 kt for this advisory due to the strong
thunderstorms leading to tropical storm conditions over areas to the
north through southeast of the center.
The initial motion vector for this advisory 325/10 kt, with Darby
becoming increasingly shallow as it is embedded in an environment
characterized by strong southwesterly shear. Although SHIPS
guidance reduces the shear on days 2 and 3, Darby is not expected to
survive the trek over increasingly cooler waters, and degeneration
to a post-tropical low is expected relatively soon. Global models
indicate Darby will track toward the northwest before weakening to a
trough by day 3, and the official forecast follows closely. The
updated track forecast follows the trajectory of the previous
closely, except for a slight westward shift in order to come in line
with the latest GFEX guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0900Z 22.4N 159.4W 35 KT 40 MPH
12H 25/1800Z 23.3N 160.3W 30 KT 35 MPH
24H 26/0600Z 24.4N 161.7W 30 KT 35 MPH
36H 26/1800Z 25.6N 163.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 27/0600Z 27.1N 164.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 28/0600Z...DISSIPATED
$$
Forecaster Birchard