WDXS31 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (HAYLEY) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.2S 119.6E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 220 NM NORTHWEST OF BROOME, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 10S HAS CONTINUED TO STEADILY INTENSIFY OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT
DEEP CONVECTIVE BANDING WRAPPING AROUND THE CENTER OF THE VERY
COMPACT CIRCULATION. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON AN EMERGENT CENTER FEATURE EVIDENT IN MSI AND
RECENT SATELLITE POSITION FIXES FROM PGTW, DEMS, AND APRF. THE
INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A CONSENSUS OF SUBJECTIVE DVORAK AND AUTOMATED INTENSITY
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND 290352Z
OCEANSAT-3 PASS

CURRENT STEERING MECHANISM: POLEWARD EXTENSION OF DEEP LAYER
NEAR-EQUATORIAL RIDGE CENTERED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   DEMS: T3.5 - 55 KTS
   APRF: T4.0 - 65 KTS
   CIMSS SATCON: 53 KTS AT 290536Z
   CIMSS ADT: 53 KTS AT 290530Z
   CIMSS AIDT: 42 KTS AT 290530Z
   CIMSS D-MINT: 57 KTS AT 290536Z
   CIMSS D-PRINT: 53 KTS AT 290640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC 10S WILL TURN EASTWARD OVER THE NEXT 24
HOURS AS THE STEERING RIDGE TO THE NORTHEAST REORIENTS. THE SYSTEM
WILL CONTINUE TO FOLLOW THE PERIPHERAL FLOW ASSOCIATED WITH THIS
RIDGE THROUGHOUT THE FORECAST PERIOD, LIKELY MAKING LANDFALL ALONG
THE DAMPIER PENINSULA BETWEEN TAU 24 AND 36. ENVIRONMENTAL
CONDITIONS INCLUDING LOW VERTICAL WIND SHEAR, A VERY WARM SEA
SURFACE, AND MODERATE POLEWARD OUTFLOW ARE FAVORABLE FOR ONGOING
INTENSIFICATION IN THE NEAR-TERM. HOWEVER, INCREASING MID-LEVEL
VERTICAL WIND SHEAR AND ENTRAINMENT OF DRIER AIR WILL BEGIN TO
INFLUENCE THE SYSTEM BY TAU 24 AND STEADY WEAKENING IS EXPECTED
THEREAFTER DUE TO THE DETERIORATING ENVIRONMENTAL CONDITIONS AND
PASSAGE OVER LAND. THE SYSTEM WILL DISSIPATE OVER LAND BY TAU 72.

MODEL DISCUSSION: THE CURRENT JTWC FORECAST LIES WITH A GROUPING OF
CONSENSUS TRACK FORECAST MODELS THAT INCLUDES THE ECMWF, GFS AND
UKMET DETERMINISTIC SOLUTIONS AS WELL AS THE GEFS AND ECMWF
ENSEMBLE MEANS. THIS GROUPING HAS CONSISTENTLY DEPICTED A GRADUAL
EASTWARD TURN AND PASSAGE VERY NEAR OR OVER THE DAMPIER PENINSULA
FOR THE PAST SEVERAL MODEL RUNS, AND THE OBSERVED TRACK HAS BEEN
CONSISTENT WITH THESE SOLUTIONS THUS FAR. ALL OF THESE SOLUTIONS
ARE TIGHTLY PACKED UNTIL TAU 36 BUT SPREAD INCREASES IN BOTH THE
CROSS-TRACK AND ALONG-TRACK DIRECTIONS. HOWEVER, THIS DIVERGENCE
OCCURS AFTER THE SYSTEM HAS MADE LANDFALL AND DISSIPATION IS WELL
UNDERWAY. THE CURRENT FORECAST TRACK LIES CLOSE TO THE PREVIOUS
FORECAST, BRACKETED BY THE PRIMARY MODEL GROUPING. INTENSITY
FORECAST GUIDANCE SUPPORTS NEAR-TERM INTENSIFICATION FOLLOWED BY
STEADY TO RAPID WEAKENING. THE LATEST INTERPOLATED HAFS-A RUN PEAKS
THE SYSTEM AT 75 KNOTS IN 12 HOURS, BEFORE THE SYSTEM CONTENDS WITH
INCREASING MID-LEVEL VERTICAL WIND SHEAR AND CONSEQUENT
ENTRAINMENT OF DRIER AIR FROM THE SOUTHWEST. A HOST OF RAPID
INTENSIFICATION AIDS WERE ALSO TRIGGERED ON THE LATEST RUN,
SUGGESTING THE PEAK COULD POTENTIALLY EXCEED 75 KNOTS. ALTHOUGH THE
COMPACT SYSTEM IS VULNERABLE TO ENVIRONMENTAL FACTORS AND IT
APPEARS THAT AT LEAST SOME WEAKENING IS LIKELY PRIOR TO LANDFALL,
INTENSITY AT LANDFALL WILL BE HIGHLY DEPENDENT ON HOW MUCH THE
SYSTEM INTENSIFIES OVER THE NEXT 12 TO 24 HOURS AS THE TIME
REMAINING TO BEGIN WEAKENING PRIOR TO LANDFALL WILL BE SHORT.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM//
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