WTPA42 PHFO 041502

TCDCP2



TROPICAL STORM OHO DISCUSSION NUMBER   6

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP072015

500 AM HST SUN OCT 04 2015



SHOWERS AND THUNDERSTORMS HAVE BEEN STEADILY RE-DEVELOPING AND

INTENSIFYING NEAR THE CENTER OF OHO OVER THE PAST SEVERAL HOURS...

WHILE THE SYSTEM HAS BECOME INCREASINGLY SEPARATED FROM THE

DEEP CONVECTION WELL TO THE SOUTHEAST. THUS OHO IS ONCE AGAIN

TAKING ON THE APPEARANCE OF A TYPICAL TROPICAL CYCLONE...RATHER

THAN THAT OF A MONSOON DEPRESSION. DVORAK CURRENT INTENSITY

ESTIMATES ARE 2.5/35 KT FROM PGTW AND 2.0/30 KT FROM PHFO AND SAB.

THE MULTI-PLATFORM SATELLITE SURFACE WIND ANALYSES FROM RAMMB/CIRA

ANALYZED AN AREA OF 35 KT WINDS TO THE NORTHEAST OF THE

CENTER...WITH A MAX WIND OF 44 KT...WHILE SATCON AND ADT ANALYSES

FROM UW-CIMSS INDICATE AN INTENSITY NEAR 40 KT. BASED ON A BLEND OF

THIS DATA...THE INITIAL INTENSITY FOR THIS ADVISORY HAS BEEN

MAINTAINED AT 35 KT.



A COMPLEX PATTERN ALOFT CURRENTLY HAS OHO IN AN ENVIRONMENT OF

EASTERLY SHEAR...ON THE ORDER OF ABOUT 10-15 KT...ACCORDING TO

UW-CIMSS AND SHIPS ANALYSES...WITH THE CENTER ESTIMATED TO BE JUST

EAST OF THE DEEP CONVECTION. WITH OHO SOUTH OF A WEAK MID-LEVEL

RIDGE THAT EXTENDS WESTWARD FROM A HIGH IN THE EASTERN PACIFIC...AND

THE SYSTEM APPARENTLY RE-GAINING VERTICAL DEPTH...IT HAS BEEN MOVING

WEST-NORTHWESTWARD...285/06 KT...SINCE THE PREVIOUS ADVISORY. AS OHO

HAS BEEN IN AN AREA OF WEAK AND VARIABLE STEERING CURRENTS...

FORECASTING WHAT HAS BEEN AN ERRATIC MOTION OVER THE PAST 24 TO 36

HOURS HAS BEEN A CHALLENGE.



HAVING SAID THAT...THE UPDATED TRACK FORECAST CALLS FOR SLOW-MOVING

OHO TO CONTINUE MOVING TOWARD THE WEST-NORTHWEST TODAY BEFORE

TURNING TOWARD THE NORTHWEST BY TONIGHT...STEERED BY THE

AFOREMENTIONED RIDGE. A TURN TOWARD THE NORTH AND THEN NORTHEAST...

WITH AN INCREASE IN FORWARD SPEED...IS EXPECTED TO GRADUALLY

COMMENCE ON MONDAY AND CONTINUE THROUGH THE END OF THE FORECAST

PERIOD. THIS OCCURS AS A VIGOROUS SHORTWAVE TROUGH DIGS SOUTHWARD

INTO A PERSISTENT LONGWAVE TROUGH THAT IS NORTH OF HAWAII...AND

ERODES THE RIDGE. THE DIGGING TROUGH WILL BRING AN INCREASING

SOUTHWESTERLY STEERING FLOW THAT WILL ACCELERATE OHO TOWARD THE

NORTHEAST ON DAYS 4 AND 5. THE UPDATED FORECAST IS SIMILAR TO THE

PREVIOUS...AND IS CLOSE TO THE GFEX...BUT NOT AS FAST IN THE LATER

PERIODS. GREATER WEIGHT IS PLACED ON THE GFS VERSUS THE

ECMWF...WHICH INDICATES A MUCH FASTER MOTION TO THE NORTHEAST ON

DAYS 4 AND 5. THE GFS IS SLOWER WITH THE FORWARD MOTION OF OHO IN

THE LATER PERIODS AS IT INTERACTS WITH A DEVELOPING AREA OF LOW

PRESSURE TO ITS EAST. WHILE THE DEVELOPMENT OF THIS LOW MAY SEEM

SOMEWHAT SPURIOUS...LATEST SATELLITE IMAGES INDICATE PERSISTENT DEEP

CONVECTION IN AN AREA THAT THE GFS INSISTS WILL SPAWN A TROPICAL

LOW.



THE LATEST INTENSITY GUIDANCE INDICATES THAT OHO WILL HAVE A

DIFFICULT TIME BECOMING A HURRICANE...DESPITE SUFFICIENTLY WARM SEA

SURFACE TEMPERATURES ALONG THE FORECAST TRACK OVER THE NEXT COUPLE

OF DAYS. MODERATE EASTERLY SHEAR OVER THE NEXT TWO DAYS IS EXPECTED

TO BE A LIMITING FACTOR BEFORE STRONGER SOUTHWESTERLY SHEAR ON DAYS

3 TO 5 LEADS TO A WEAKENING TREND. THE INTENSITY FORECAST IS CLOSE

TO THE IVCN AND NOW DOES NOT FORECAST OHO TO BECOME A HURRICANE. AN

ASCAT PASS AROUND 0758Z INDICATED THAT ALTHOUGH STRONG WESTERLY

WINDS ARE STILL RACING BY TO THE SOUTH AND SOUTHEAST OF OHO...THESE

WINDS HAVE WEAKENED. AS OPPOSED TO WHEN OHO HAD THE APPEARANCE OF A

MONSOON GYRE YESTERDAY...THESE WINDS WILL NO LONGER BE CONSIDERED

DIRECTLY RELATED TO THE CIRCULATION OF THE CYCLONE. THEREFORE THE

LARGE TROPICAL STORM FORCE RADII IN THE SOUTHERN SEMICIRCLE THAT

WERE INDICATED IN THE PREVIOUS COUPLE OF ADVISORIES HAVE BEEN

REDUCED DRAMATICALLY.



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 THIS EVENING AND MONDAY MORNING. THE G-IV

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

HIGH-ALTITUDE FLIGHTS PLANNED FOR THE NEXT TWO DAYS.





FORECAST POSITIONS AND MAX WINDS



INIT  04/1500Z 13.5N 155.2W   35 KT  40 MPH

 12H  05/0000Z 13.8N 155.3W   40 KT  45 MPH

 24H  05/1200Z 14.3N 155.2W   45 KT  50 MPH

 36H  06/0000Z 15.0N 154.5W   50 KT  60 MPH

 48H  06/1200Z 16.0N 153.4W   55 KT  65 MPH

 72H  07/1200Z 17.6N 151.4W   60 KT  70 MPH

 96H  08/1200Z 20.5N 148.5W   55 KT  65 MPH

120H  09/1200Z 25.0N 146.0W   50 KT  60 MPH



$$



FORECASTER BIRCHARD