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TROPICAL DEPRESSION THREE-C DISCUSSION NUMBER   1
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP032015
1100 AM HST THU AUG 20 2015
 
Satellite imagery showed that a tropical disturbance southeast of
the main Hawaiian Islands has developed sufficient persistent deep
convection around a closed circulation to be considered a tropical
depression. Therefore...advisories are being initiated on Tropical
Depression Three-C. This is the sixth tropical cyclone in the
Central NORTH Pacific basin for the 2015 season. Dvorak intensity
estimates from the fix agencies came in at 30 KT from PHFO and
SAB...AND 25 KT FROM JTWC. THE initial intensity WILL BE 30 KT for
this FORECAST PACKAGE.

The depression is moving AT 280/14 kt. THE LOW CONFIDENCE OF THE
CENTER POSITIONS OVER THE PAST 12 TO 24 HOURS MAKES THIS MOVEMENT
UNCERTAIN. Objective aids are tightly lined up with a general
WEST TO west-northwest motion through TWO days as Three-C moves
south of a MID-LEVEL ridge building westward. IN ABOUT THREE DAYS...
a weakness is forecast to develop in the ridge which would result in
a SLOWING OF FORWARD MOTION AND A gradual TURN TOWARD THE NORTH OR
NORTH-northeast. THE MAIN DYNAMICAL aids differ on the LOCATION of
the turn WITH THE HWRF AND GFS ON THE EAST SIDE OF THE ENVELOPE AND
THE ECMWF ON THE WEST SIDE. THE TIMING OF THE TURN WILL DEPEND
GREATLY ON WHEN THE WEAKNESS IN THE RIDGE OCCURS. THE LONGER IT
TAKES...THE FARTHER WEST THE CYCLONE WILL MOVE BEFORE MAKING THE
TURN AND THIS ASPECT OF THE FORECAST CONTAINS A HIGH AMOUNT OF
UNCERTAINTY. THE FORECAST CLOSELY FOLLOWS THE DYNAMIC CONSENSUS
THROUGH THE PACKAGE WITH THE TROPICAL CYCLONE APPROACHING
THE WEST SIDE OF THE MAIN HAWAIIAN ISLANDS IN FIVE DAYS. 

TROPICAL DEPRESSION THREE-C IS MOVING OVER VERY WARM WATER...OVER
29C...BASED ON THE LATEST ANALYSIS. THERE APPEARS TO BE SOME
EASTERLY SHEAR IMPACTING THE SYSTEM BASED ON THE FLATTENING OF THE
HIGH LEVEL CLOUDS ON THE EAST SIDE AND THE CIMSS 1800 UTC SHEAR
ANALYSIS SHOWING MORE THAN 20 KT. THIS SHEAR IS FORECAST TO STEADILY
DECREASE OVER THE NEXT TWO TO THREE DAYS AS THE DEPRESSION MOVES
UNDERNEATH THE UPPER LEVEL RIDGE AXIS. THE WEAKENING SHEAR AND
THE VERY WARM WATERS SHOULD ALLOW FOR STEADY DEVELOPMENT. THE
SHIPS RAPID INTENSIFICATION PARAMETER ALSO SHOWS A 47 PERCENT
PROBABILITY FOR THE 25 KT THRESHOLD. THUS...THE FORECAST CALLS FOR
THREE-C TO BECOME A TROPICAL STORM WITHIN THE NEXT 24 HOURS AND A
HURRICANE IN ABOUT TWO DAYS SOUTH-SOUTHWEST OF THE MAIN HAWAIIAN
ISLANDS. THIS IS IN LINE WITH THE IVCN CONSENSUS.

U.S AIR FORCE RESERVE WEATHER RECONNAISSANCE ASSETS ARE IN THE
PROCESS OF DEPLOYING TO HAWAII AND A WC-130J IS SCHEDULED TO MAKE AN
INITIAL PASS THROUGH THREE-C FRIDAY EVENING.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/2100Z 11.0N 150.2W   30 KT  35 MPH
 12H  21/0600Z 12.1N 152.0W   40 KT  45 MPH
 24H  21/1800Z 12.9N 154.8W   45 KT  50 MPH
 36H  22/0600Z 13.7N 158.0W   60 KT  70 MPH
 48H  22/1800Z 14.9N 160.8W   70 KT  80 MPH
 72H  23/1800Z 17.4N 163.4W   80 KT  90 MPH
 96H  24/1800Z 19.6N 163.0W   85 KT 100 MPH
120H  25/1800Z 21.0N 162.0W   85 KT 100 MPH
 
$$
Forecaster Kodama
 
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