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
