“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”National Weather Service on Oct. 3, 2015