WTPA42 PHFO 040859

TCDCP2



TROPICAL STORM OHO DISCUSSION NUMBER   5

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP072015

1100 PM HST SAT OCT 03 2015



IT APPEARS THAT THE INTERPLAY BETWEEN OHO AND STRONG WESTERLY WINDS

SOUTH AND SOUTHWEST OF THE CYCLONE IS PREVENTING SIGNIFICANT

ORGANIZATION THIS EVENING. THE MOST WIDESPREAD AND VIGOROUS

CONVECTION IS DISPLACED WELL SOUTHEAST OF THE CENTER...BUT CURVED

BANDS OF CONVECTION HAVE RE-DEVELOPED CLOSER TO THE CENTER IN THE

NORTHERN SEMICIRCLE OVER THE PAST COUPLE OF HOURS. DVORAK CURRENT

INTENSITY ESTIMATES FROM PHFO AND PGTW INDICATED 2.5/35 KT WHILE SAB

OBTAINED 1.5/25 KT. THE INITIAL INTENSITY FOR THIS ADVISORY WILL

REMAIN 35 KT...PARTIALLY DUE TO THE RENEWED CONVECTION.



THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS 050/04 KT.

OHO IS EMBEDDED IN AN AREA OF WEAK STEERING FLOW...SOUTH OF A WEAK

MID-LEVEL RIDGE THAT EXTENDS WESTWARD FROM A HIGH IN THE EASTERN

PACIFIC. NORTH OF THIS RIDGE AND NORTH OF HAWAII...A PERSISTENT

LONG WAVE TROUGH ALOFT FEATURES A DISTANT CLOSED LOW THAT IS IN THE

PROCESS OF WEAKENING. THE EXPECTATION IS FOR OHO TO MOVE SLOWLY

TOWARD THE NORTHEAST OVERNIGHT...INFLUENCED BY THE STRONG WESTERLY

WINDS TO THE SOUTH. A TURN TOWARD THE NORTHWEST IS FORECAST ON

SUNDAY...TEMPORARILY STEERED BY THE MID-LEVEL RIDGE AS THE SYSTEM

SLOWLY RE-GAINS ORGANIZATION AND VERTICAL DEPTH. ON SUNDAY NIGHT AND

MONDAY...A VIGOROUS NEW SHORTWAVE WILL DIG SOUTHWARD INTO THE

LONGWAVE TROUGH TO THE NORTH...ERODING THE RIDGE AND WEAKENING

STEERING CURRENTS TO NEAR ZERO. AS THE TROUGH DIGS FURTHER

SOUTH...THE EXPECTATION IS THAT INCREASING SOUTHWESTERLY STEERING

FLOW WILL TAKE OHO MORE RAPIDLY TOWARD THE NORTHEAST ON DAYS 4 AND

5. THE UPDATED FORECAST IS SIMILAR TO THE PREVIOUS...BUT INDICATES A

MORE RAPID NORTHEASTERLY MOTION IN THE LATER FORECAST PERIODS. THE

DAY 5 POSITION IS SIGNIFICANTLY MORE NORTHEAST THAN THE PREVIOUS...

TO BE CLOSER TO THE TVCN AND GFEX CONSENSUS. THIS GUIDANCE HAS SHIFTED

TO THE NORTHEAST DUE TO THE INPUT FROM THE LATEST ECMWF RUN...WHICH

HAS OHO ABOUT 900 MILES FARTHER NORTHEAST ON DAY 5 THAN THE GFS.



LIGHT SHEAR...SUFFICIENTLY WARM SEA SURFACE TEMPERATURES AND A

MOIST ATMOSPHERIC ENVIRONMENT ARE PROJECTED ALONG THE FORECAST

TRACK. THUS THE INTENSITY FORECAST CONTINUES TO CALL FOR STEADY

INTENSIFICATION...WITH OHO STILL EXPECTED TO BECOME A MINIMAL

HURRICANE. AS THE SHEAR INCREASES DUE TO THE DIGGING TROUGH ALOFT IN

THE LATER PERIODS...A WEAKENING TREND IS INTRODUCED. AN EARLIER

ASCAT PASS INDICATED THAT TROPICAL STORM FORCE WINDS EXTENDED WELL

SOUTHEAST OF THE CENTER...AND THIS FORECAST MAINTAINS FAIRLY LARGE

RADII IN THE SOUTHERN SEMICIRCLE. AS OHO BECOMES INCREASINGLY

ORGANIZED OVER THE NEXT COUPLE OF DAYS...AND IS ABLE TO SEPARATE

FROM THE PERSISTENT AND STRONG EL NINO-RELATED LOW-LEVEL WESTERLIES

NEAR THE EQUATOR...THE ASSOCIATED WIND FIELD IS FORECAST TO

CONTRACT.



THE 53RD WEATHER RECONNAISSANCE SQUADRON HAS BEEN TASKED TO FLY THIS

SYSTEM IN SUPPORT OF CPHC OPERATIONS. INITIAL FLIGHTS INTO THE

SYSTEM ARE PLANNED FOR SUNDAY EVENING AND MONDAY MORNING. THE G-IV

AIRCRAFT IS ALSO HEADING TO HAWAII TO FLY SYNOPTIC MISSIONS...WITH

HIGH-ALTITUDE FLIGHTS PLANNED FOR SUNDAY AND MONDAY MORNINGS...IN

ORDER FOR THE DATA TO BE UTILIZED BY AFTERNOON MODEL RUNS.





FORECAST POSITIONS AND MAX WINDS



INIT  04/0900Z 13.3N 154.2W   35 KT  40 MPH

 12H  04/1800Z 13.7N 154.2W   40 KT  45 MPH

 24H  05/0600Z 14.2N 154.4W   45 KT  50 MPH

 36H  05/1800Z 14.7N 154.2W   55 KT  65 MPH

 48H  06/0600Z 15.0N 153.8W   60 KT  70 MPH

 72H  07/0600Z 16.0N 151.5W   65 KT  75 MPH

 96H  08/0600Z 18.6N 150.0W   65 KT  75 MPH

120H  09/0600Z 24.0N 147.0W   60 KT  70 MPH



$$



FORECASTER BIRCHARD