WDXS31 PGTW 281500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (TEN) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.6S 119.4E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 304 NM NORTH-NORTHWEST OF BROOME,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 04S HAS SLOWLY DEVELOPED OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS PERSISTENT DEEP
CONVECTION OVER A COMPACT LOW-LEVEL CIRCULATION CENTER EVIDENT IN A
280825Z SSMIS PASS. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON RECENT SATELLITE POSITION FIXES FROM PGTW,
APRF, AND DEMS AS WELL AS THE 280825Z SSMIS DATA. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE FAVORING THE
UPPER END OF THE SUBJECTIVE AND AUTOMATED INTENSITY ESTIMATES
LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP LAYER RIDGING TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   APRF: T2.5 - 35 KTS
   CIMSS ADT: 41 KTS AT 281140Z
   CIMSS AIDT: 33 KTS AT 281140Z
   CIMSS D-MINT: 33 KTS AT 280825Z
   CIMSS D-PRINT: 35 KTS AT 281230Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 IS EXPECTED TO TRACK GENERALLY POLEWARD
OVER THE NEXT 12 HOURS UNDER THE CONTINUED STEERING INFLUENCE OF
DEEP LAYER RIDGING TO THE EAST. THEREAFTER, THE SYSTEM WILL TAKE A
GRADUAL EASTWARD TURN AS RIDGING TO THE EAST REORIENTS AND A
BUILDING NEAR-EQUATORIAL RIDGE TO THE NORTH BECOMES THE DOMINANT
STEERING MECHANISM. THE SYSTEM IS EXPECTED TO CONTINUE INTENSIFYING
FOR THE NEXT 24 HOURS UNDER THE FAVORABLE INFLUENCES OF LOW
VERTICAL WIND SHEAR, PASSAGE OVER VERY WARM WATER, AND POLEWARD
OUTFLOW ENHANCED BY PASSAGE OF AN UPPER-LEVEL TROUGH TO THE SOUTH.
AFTER TAU 24, THE SYSTEM WILL ENCOUNTER INCREASING WESTERLY FLOW
ALOFT AS THE UPPER-LEVEL FLOW PATTERN SHIFTS, HALTING THE
INTENSIFICATION TREND. INCREASING SHEAR AND CONSEQUENT ENTRAINMENT
OF DRIER AIR WILL WEAKEN THE SYSTEM BEFORE IT SKIRTS OR MAKES
LANDFALL ALONG THE DAMPIER PENINSULA BETWEEN TAUS 48 AND 72. THE
UNFAVORABLE UPPER-LEVEL FLOW PATTERN AND PASSAGE OVER LAND WILL
DISSIPATE THE SYSTEM BY TAU 72.

MODEL DISCUSSION: NUMERICAL MODEL TRACK FORECAST GUIDANCE REMAINS
IN GOOD AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO. THE
CURRENT FORECAST LIES WITH A PRIMARY GROUPING OF MODELS INCLUDING
THE ECMWF DETERMINISTIC, ECMWF ENSEMBLE, GFS, GEFS, AND FGN
SOLUTIONS, AMONG WHICH THERE IS LITTLE SPREAD IN TRACK ORIENTATION
BUT NOTEWORTHY SPREAD IN FORWARD SPEED AFTER TAU 48. THUS, WHILE
THE POSSIBLE LOCATION OF LANDFALL FALLS WITHIN A NARROWER RANGE
ACCORDING TO THE LATEST MODEL GUIDANCE, THERE IS RELATIVELY MORE
UNCERTAINTY IN THE TIMING. INTENSITY FORECAST GUIDANCE IS IN VERY
GOOD AGREEMENT DURING THE LATER WEAKENING STAGE AFTER TAU 36, BUT
THE RANGE OF POTENTIAL PEAK INTENSITIES LIES BETWEEN 50 AND 85
KNOTS IN THE FORECAST PACKAGE. THE CURRENT INTENSITY FORECAST LIES 
NEAR THE MULTI-MODEL CONSENSUS WITH MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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