WDXS31 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (FIVE) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.8S 94.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 1267 NM WEST-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 01 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS IMPROVED
DIFFUSE POLEWARD AND WESTWARD OUTFLOW EVIDENT IN A FORMATIVE
CENTRAL DENSE OVERCAST (CDO) FEATURE, WITH PERIODIC EXHAUST
FILAMENTS BEING THROWN OFF TO THE EQUATORWARD SIDE. DEEP CONVECTION
HAS PERSISTED IN THE SOUTHWEST QUADRANT AND IS OBSCURING THE LOW
LEVELS, THOUGH IT IS WORTH NOTING THAT THERE IS QUITE A BIT OF
PRESSURE BEING EXPERIENCED ON THE NORTHEAST SIDE. A 261851Z AMSR2
IMAGE CONFIRMED THE PRESENCE OF ELEVATED WIND VELOCITIES (30-40
KTS) IN THE SOUTHWEST QUADRANT UNDER THE PLUME OF DEEP CONVECTION.
EARLIER SCATTEROMETRY PROVIDED A SIMILAR STORY, BUT REVEALED THE
SYSTEM HAD NOT YET BECOME ORGANIZED INTO A CLOSED CIRCULATION. ONCE
THE SYSTEM COULD BE ASSESSED WITH ANIMATED VISIBLE SATELLITE IMAGERY, 
IT WAS APPARENT THE LOW LEVELS HAD DEVELOPED INTO A CLOSED CIRCULATION. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE, THE INITIAL 
INTENSITY IS ASSESSED WITH HIGH CONFIDENCE, AND THE INITIAL WIND RADII 
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED AMSR2 
DATA. AGENCY SUBJECTIVE DVORAK ESTIMATES CONCUR WITH THE INTENSITY 
ASSESSMENT.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   APRF: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: THE SYSTEM HAS FORMED ALONG A MONSOON TROUGH,
UP AGAINST A TIGHTENED PRESSURE GRADIENT TO THE SOUTH, AND
UNDERNEATH AN AREA OF UPPER LEVEL POLEWARD DIFFLUENCE. THIS EXHAUST
MECHANISM HAS AIDED IN THE LONG-AWAITED DEVELOPMENT OF A FULLY
CLOSED LOW LEVEL CIRCULATION CENTER OVER THE PAST 12 HOURS. DESPITE
UNFAVORABLE DEEP LAYERED VERTICAL WIND SHEAR OF 25-30 KTS, DUE
PRIMARILY TO DIRECTIONAL SHEAR, THE PERSISTENT DEEP CONVECTION AND
FAVORABLE POLEWARD OUTFLOW IS EXPECTED TO MAINTAIN THE ASSESSED
INTENSITY THROUGHOUT THE FORECAST PERIOD UNTIL TAU 48 WITH LITTLE
FLUCTUATION IN SUSTAINED WIND SPEEDS. BALMY TROPICAL AIR AND WARM
SEA SURFACE TEMPERATURES (SST) ARE CONTRIBUTING FAVORABLY TO THE
DEVELOPMENT AND SUSTAINMENT OF THE SYSTEM, AND SSTS WILL REMAIN
WARMER THAN 26C FOR THE DURATION OF THE FORECAST. HOWEVER, THE
OCEAN HEAT CONTENT (OHC) VALUES WILL GRADUALLY DECLINE AT EACH TAU,
AND THIS COULD BECOME AN ISSUE DUE TO THE CLIMATOLOGICALLY SLOW
TRACK SPEEDS EXPECTED. THE CURRENT STEERING MECHANISM DRIVING THE
SYSTEM SLOWLY SOUTHEASTWARD WILL BE OVERTAKEN BY A BUILDING
SUBTROPICAL RIDGE TO THE SOUTH, WHICH WILL TURN THE TRACK WESTWARD
AFTER TAU 60. INCREASING SUBSIDENCE AND LESSENING OHC VALUES WILL
BRING THE SYSTEM TO BELOW WARNING THRESHOLDS UNTO GRADUAL
DISSIPATION OVER WATER BY TAU 72.

MODEL DISCUSSION: THE TRACK FORECAST SHARES GOOD CONSENSUS
REGARDING THE INITIAL SOUTHEASTWARD DRIFT AND OVERALL TIMING OF THE
WESTWARD TURN NEAR TAU 60. HOWEVER, DUE TO VARIATIONS IN FORWARD
TRACK SPEED, THE LOCATION OF THE WESTWARD PIVOT IS UNCERTAIN; THE
GFS AND ECMWF TRACK GUIDANCE DIFFERS BY APPROXIMATELY 120 NM AT TAU
60. ENSEMBLE AND DETERMINISTIC MODELS HAVE MAINTAINED GOOD
AGREEMENT CONCERNING THE BORDERLINE NATURE OF THIS SYSTEM IN TERMS
OF THE FLATLINED INTENSITY. THE JTWC FORECAST CLOSELY MATCHES THE
INTENSITY CONSENSUS, RESULTING IN A HIGH CONFIDENCE INTENSITY
FORECAST. THE JTWC TRACK FORECAST IS PREDICTED WITH MEDIUM
CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: HIGH//
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