WDXS31 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10S (HAYLEY) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.1S 119.4E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 279 NM NORTHWEST OF BROOME, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 10S (HAYLEY) WITH A HIGHLY COMPACT LOW-LEVEL CIRCULATION
CENTER (LLCC) THAT IS OBSCURED BY PERSISTENT DEEP CONVECTION. A
281405Z METOP-C ASCAT IMAGE REVEALED THAT THE EXTENT OF 34 KNOT
WINDS IS EXTREMELY SMALL (AROUND 30 NM) AND IS VERY SYMMETRICAL.
THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS
OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. ENVIRONMENTAL ANALYSIS
INDICATES THAT 10S IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY
MODERATE POLEWARD AND EQUATORWARD OUTFLOW ALOFT, LOW (5-10 KTS)
VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: PERSISTENCE FROM THE 281405Z METOP-C
ASCAT PASS

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A
NEAR-EQUATORIAL RIDGE (NER) CENTERED OVER THE BANDA SEA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   APRF: T3.0 - 45 KTS
   CIMSS SATCON: 40 KTS AT 281753Z
   CIMSS ADT: 51 KTS AT 281800Z
   CIMSS AIDT: 40 KTS AT 281800Z
   CIMSS D-MINT: 37 KTS AT 281703Z
   CIMSS D-PRINT: 43 KTS AT 281800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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 FORECAST TO TRACK SOUTHEASTWARD,
ALONG THE SOUTHWESTERN PERIPHERY OF THE NER CENTERED OVER THE BANDA
SEA THROUGH TAU 24. NEAR TAU 24, 10S IS FORECAST TO TURN EASTWARD
AS IT ROUNDS THE SOUTHERN EXTENT OF THE NER. LANDFALL ALONG THE TIP
OF THE DAMPIER PENINSULA IS FORECAST TO OCCUR BETWEEN TAU 36 AND 48
WITH A FINAL LANDFALL JUST AFTER TAU 48. AFTER THE FINAL LANDFALL,
10S IS EXPECTED TO CONTINUE TRACKING EASTWARD THROUGH THE REMAINDER
OF THE FORECAST PERIOD. REGARDING INTENSITY, 10S IS FORECAST TO
RAPIDLY INTENSIFY OVER THE NEXT 24 HOURS AS THE SYSTEM BEGINS TO
TAP INTO AN ENHANCED POLEWARD OUTFLOW CHANNEL DUE TO AN UPPER-LEVEL
TROUGH TO THE SOUTH. A PEAK INTENSITY IS FORECAST TO BE AROUND 75
KTS NEAR TAU 24. AFTER TAU 24, NORTHEASTERLY SHEAR IS EXPECTED TO
QUICKLY INCREASE, CAUSING 10S TO WEAKEN AS IT APPROACHES THE
KIMBERLEY COAST. AFTER THE SYSTEM MAKES A FINAL LANDFALL, TERRAIN
INTERACTION WILL ERODE THE VORTEX AND CAUSE IT TO WEAKEN BELOW 35
KTS AROUND TAU 72.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH THE EXCEPTION OF NAVGEM, WHICH TRACKS THE VORTEX
MUCH FURTHER NORTH THAN THE REMAINDER OF GUIDANCE. DISCOUNTING
NAVGEM, THERE IS A 65 NM CROSS-TRACK SPREAD AT TAU 48. AFTER TAU
48, MODELS SLIGHTLY DIVERGE, PARTICULARLY IN THE ALONG-TRACK
DIRECTION. THE GOOGLE DEEPMIND AND EC-AIFS MODELS ARE THE FASTEST
WHILE THE GFS AND ECMWF ENSEMBLE MEANS ARE THE SLOWEST. AT TAU 72,
ALONG-TRACK SPREAD INCREASES TO AROUND 120 NM, CAUSING THERE TO BE
SLIGHT UNCERTAINTY REGARDING TRACK SPEEDS NEAR THE END OF THE
FORECAST PERIOD. THE JTWC TRACK FORECAST IS PLACED SLIGHTLY SOUTH
OF THE CONSENSUS, TO OFFSET NAVGEM, WITH MEDIUM CONFIDENCE.
INTENSITY GUIDANCE AGREES ON INTENSIFICATION THROUGH TAU 24 WITH
WEAKENING AFTERWARD. HOWEVER, MULTIPLE RAPID INTENSIFICATION (RI)
AIDS ARE TRIGGERED THIS MODEL RUN, CAUSING THERE TO BE SOME
INHERENT UNCERTAINTY. A TIGHT GROUPING OF THE RI AIDS, HAFS-A,
HWRF, AND COAMPS-TC CREATE A SMALL RANGE OF PEAK INTENSITIES FROM
70-80 KTS AT TAU 24. THE JTWC INTENSITY FORECAST FOLLOWS SUIT, AND
CALLS FOR A PEAK INTENSITY OF 75 KTS AT TAU 24. ALL MODELS THEN
AGREE ON WEAKENING THROUGH TAU 72, AND THE JTWC INTENSITY FORECAST
FOLLOWS THE CONSENSUS THROUGH THE REMAINDER OF THE FORECAST PERIOD.


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