WTPA42 PHFO 060246

TCDCP2



TROPICAL STORM OHO DISCUSSION NUMBER  12

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP072015

500 PM HST MON OCT 05 2015



ALTHOUGH STILL OBSCURED...VISIBLE SATELLITE LOOP...A 2358 UTC AMSUB

PASS...AND EXTRAPOLATION OF EARLIER AIRCRAFT DATA SHOW THE LLCC

REMAINS NEAR THE NORTHEAST EDGE OF DEEPEST CONVECTION. SHEAR HAS

DECREASED SINCE THIS MORNING AND IS NOW 10 KT OR LESS ACCORDING TO

UW-CIMSS AND SHIPS ANALYSES...SO THE LLCC IS LIKELY WITHIN 20 NM OF

THE APPARENT UPPER LEVEL ROTATION. THAT SAID...EVERY HOUR WITHOUT

FRESH AIRCRAFT DATA INCREASES FIX UNCERTAINTY. SUBJECTIVE DVORAK

SATELLITE INTENSITY ESTIMATES RANGE FROM 3.0...45 KT...FROM

JTWC...TO 3.5...55 KT...FROM PHFO AND SAB. UW-CIMSS ADT WAS 3.4...53

KT. A 2009 UTC ASCAT PASS SHOWED A SWATH OF 50 KT WINDS 30 NM SE OF

THE LLCC. EARLIER RECONNAISSANCE AIRCRAFT FOUND 55 KT SURFACE WINDS

IN THE SAME GENERAL AREA VIA SFMR. GIVEN THE INCREASED SATELLITE

INTENSITY ESTIMATES NOW MATCHING EARLIER AIRCRAFT FINDINGS...WE

WILL MAINTAIN OHO AT A 55 KT INITIAL INTENSITY.



SATELLITE ANIMATION SHOWS OHO CONTINUES TO MOVE NORTHEASTWARD...BUT

FORWARD MOTION MAY HAVE SLOWED SLIGHTLY SINCE THIS MORNING.

STEERING REMAINS RATHER WEAK...WITH A DIGGING TROUGH NORTH OF THE

MAIN HAWAIIAN ISLANDS HAVING SLIGHTLY MORE INFLUENCE OVER THIS

SYSTEM THAN AN ERODING MID-LEVEL RIDGE TO THE EAST. FORWARD MOTION

MAY HAVE SLOWED AS DECREASING SHEAR ALLOWED THE UPPER AND LOWER

CIRCULATION CENTERS TO MORE STRONGLY RECOUPLE. WHATEVER CHANGES

OCCURRED SINCE THIS MORNING...TRACK GUIDANCE REMAINS VERY TIGHTLY

PACKED...DEPICTING CONTINUED MOTION TOWARD THE NORTHEAST THROUGH

FIVE DAYS. THE CURRENT FORECAST TRACK CLOSELY FOLLOWS THE PREVIOUS

ONE...WITH THE FORECAST POSITION AT DAY FIVE NUDGED SLIGHTLY TO THE

RIGHT TO KEEP THE ENTIRE TRACK WITHIN THE CONSENSUS GUIDANCE

ENVELOPE.



SHIPS DEPICTS SHEAR INCREASING DRAMATICALLY AFTER 24

HOURS...RISING TO NEAR 50 KT BY 96 HOURS AS OHO MOVES OVER

21C WATER AND COOLER. HOWEVER...WITHIN THIS SHRINKING STRENGTHENING

WINDOW...SHIPS GUIDANCE BUILDS A COMPELLING CASE FOR AN INTENSITY

INCREASE TO MARGINAL HURRICANE STRENGTH. HWRF AND GFDL ALSO DEPICT

STRENGTHENING...BUT TO UNLIKELY INTENSITIES UP TO 84 KT.

HOWEVER...IN A NOD TO THIS GUIDANCE TREND...WE NOW FORECAST OHO WILL

BRIEFLY BECOME A HURRICANE AT 24 HOURS...FOLLOWED ALMOST IMMEDIATELY

BY WEAKENING AS MOUNTING SHEAR BEGINS TO TAKE ITS TOLL. OHO WILL

LIKELY END ITS LIFECYCLE AS A POST-TROPICAL/EXTRATROPICAL LOW OFF

THE PACIFIC NORTHWEST COASTLINE OF THE US MAINLAND AT 96 AND 120

HOURS.



AIRCRAFT FROM THE 53RD WEATHER RECONNAISSANCE SQUADRON ARE SCHEDULED

TO FLY INTO OHO THIS EVENING...AND POSSIBLY TUESDAY MORNING. THE

NOAA G-IV AIRCRAFT HAS COMPLETED ITS SYNOPTIC SAMPLING MISSION

AROUND OHO...AND ITS DATA HAS BEEN UTILIZED IN THE NEXT MODEL

INITIALIZATION.





FORECAST POSITIONS AND MAX WINDS



INIT  06/0300Z 15.0N 153.6W   55 KT  65 MPH

 12H  06/1200Z 15.8N 152.7W   60 KT  70 MPH

 24H  07/0000Z 17.3N 151.1W   65 KT  75 MPH

 36H  07/1200Z 19.7N 149.2W   60 KT  70 MPH

 48H  08/0000Z 22.9N 147.1W   55 KT  65 MPH

 72H  09/0000Z 29.8N 142.5W   50 KT  60 MPH

 96H  10/0000Z 36.6N 136.8W   40 KT  45 MPH...POST-TROP/EXTRATROP

120H  11/0000Z 43.3N 130.5W   30 KT  35 MPH...POST-TROP/EXTRATROP



$$

FORECASTER POWELL