WTPA41 PHFO 310254

TCDCP1



TROPICAL DEPRESSION NINE-C DISCUSSION NUMBER   1

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP092015

500 PM HST WED DEC 30 2015



AN AREA OF DEEP CONVECTION ALONG THE NORTHERN FLANK OF A BURST OF

WESTERLIES ALONG AND JUST SOUTH OF THE EQUATOR HAS BECOME ORGANIZED

ENOUGH TO WARRANT ADVISORIES AS A TROPICAL DEPRESSION. THIS MAKES

NINE-C THE SIXTEENTH TROPICAL SYSTEM OF THE YEAR TO EITHER FORM

WITHIN OR PASS THROUGH THE CENTRAL NORTH PACIFIC BASIN. SATELLITE

LOOP AND A MORNING WINDSAT PASS SHOW THE LLCC IS LIKELY ELONGATED

ALONG A ROUGH EAST TO WEST AXIS...WITH THE INITIAL POSITION

REPRESENTING A COMPROMISE BETWEEN THE OLD JTWC BEST TRACK BENEATH

DEEP CONVECTION AND AN EXPOSED VORTICITY CENTER FARTHER TO THE SOUTH

AND EAST PICKED UP BY PHFO AND SAB. THAT SAID...CONFIDENCE IN THE

INITIAL POSITION IS ONLY FAIR AT BEST.



SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATES RANGE FROM 1.5...25

KT...FROM SAB TO 2.0...30 KT...FROM PHFO AND JTWC. THE EARLIER

WINDSAT PASS CONTAINED A FEW BARBS OF SLIGHTLY STRONGER WINDS...SO

WE WILL COMPROMISE BY ASSIGNING AN INITIAL INTENSITY OF 30 KT FOR

THIS ADVISORY. THE BELT OF 30 KT WINDS EXTENDS FAR TO THE NORTH OF

THIS SYSTEM...AGAINST THE CONCEPTUAL MODEL OF A TROPICAL SYSTEM AND

MORE REPRESENTATIVE OF LARGER SCALE SYNOPTIC GRADIENT FLOW. THE

WESTERLIES TO THE SOUTH OF THIS SYSTEM ARE NOTICEABLY WEAKER THAN

THE GRADIENT FLOW TO THE NORTH...LIKELY CONTRIBUTING TO THE

STRETCHED OUT APPEARANCE THIS SYSTEM HAS LATE THIS AFTERNOON.



THE FORECAST TRACK FOLLOWS BAMM GUIDANCE...WHICH LIFTS NINE-C

GRADUALLY NORTHWARD AS IT SLIDES WEST ALONG THE SOUTHERN FLANK OF

THE SUBTROPICAL RIDGE. WE KEPT MOVEMENT A BIT SLOWER ALONG THE

FORECAST TRACK THAN BAMM DEPICTED TO ACCOUNT FOR CURRENT MOTION AND

AS A NOD TO SLOWER MOTION DEPICTED IN BAMS.



WE EXPECT NINE-C WILL DEVELOP SLOWLY...IF AT ALL...DUE TO STRONG

SOUTHEASTERLY SHEAR IN THE 25 TO 30 KT RANGE DEPICTED BY SHIPS. IF

THIS SYSTEM AVOIDS DISSIPATION...IT IS FORECAST TO REACH TROPICAL

STORM STRENGTH AT 72 HOURS AS IT CROSSES WARMER WATERS ACROSS THE

WESTERN PACIFIC. THE FORECAST TRACK TAKES NINE-C WEST OF THE

DATELINE BY DAY 2.





FORECAST POSITIONS AND MAX WINDS



INIT  31/0300Z  2.8N 177.8W   30 KT  35 MPH

 12H  31/1200Z  3.2N 178.8W   30 KT  35 MPH

 24H  01/0000Z  4.2N 179.8E   30 KT  35 MPH

 36H  01/1200Z  5.0N 178.2E   30 KT  35 MPH

 48H  02/0000Z  5.6N 176.4E   30 KT  35 MPH

 72H  03/0000Z  6.5N 172.4E   35 KT  40 MPH

 96H  04/0000Z  6.7N 168.2E   40 KT  45 MPH

120H  05/0000Z  5.9N 164.0E   40 KT  45 MPH



$$

FORECASTER POWELL