WDXS31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05S (FINA) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.8S 131.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 170 NM NORTH-NORTHEAST OF DARWIN,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 05S (FINA) HAS CONTINUED TO TRACK EASTWARD
UNDER THE INFLUENCE OF THE NEAR-EQUATORIAL RIDGE (NER) WITH
INCREASED DEEP CONVECTION OVER THE PAST 6 HOURS AS DEPICTED BY
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY. CONVECTIVE
CLOUD TOP TEMPERATURES AROUND THE CENTER HAVE CONTINUED TO COOL AND
THE ENVIRONMENT HAS REMAINED FAVORABLE FOR CONTINUED DEVELOPMENT
WITH WEAK RADIAL OUTFLOW, MODERATE VERTICAL WIND SHEAR (15-20 KTS),
AND WARM SEA SURFACE TEMPERATURES (30 C TO 31 C). THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EIR IMAGERY AND
AGENCY FIXES. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL NEAR-EQUATORIAL RIDGE
(NER) POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   ADRM: T3.0 - 45 KTS
   CIMSS SATCON: 47 KTS AT 181701Z
   CIMSS ADT: 53 KTS AT 181730Z
   CIMSS AIDT: 42 KTS AT 181730Z
   CIMSS D-MINT: 45 KTS AT 181611Z
   CIMSS D-PRINT: 49 KTS AT 181830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: WEAK RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE FINA WILL CONTINUE TO TRACK
EASTWARD OVER THE NEXT 24 HOURS WITH A PEAK INTENSITY OF 65 KTS
FORECASTED BETWEEN TAU 24 AND TAU 36 BEFORE COMPETING STEERING
MECHANISMS WILL CAUSE THE SYSTEM TO SLOW AND BEGIN ITS INITIAL
RECURVE TO THE SOUTHWEST. AROUND TAU 48 THE SUBTROPICAL RIDGE TO
THE SOUTH WILL DOMINATE THE STEERING PATTERN, CAUSING TC FINA
TO BEGIN TRACKING SOUTHWEST THROUGH THE REMAINDER OF THE FORECAST
PERIOD. AT THIS TIME, TC FINA WILL ENCOUNTER HIGHER VERTICAL WIND
SHEAR AND DRY AIR ENTRAINMENT AS THE SYSTEM BEGINS TRACKING TO THE
SOUTHWEST, WHICH WILL INITIATE A WEAKENING TREND AS TC FINA SCRAPES
THE NORTHERN COASTLINES OF THE NORTHERN TERRITORY AND WESTERN
AUSTRALIA. A SMALL WINDOW OF REINTENSIFICATION IS EXPECTED BETWEEN
TAU 96 AND TAU 120 AS THE VORTEX REEMERGES OVER THE TIMOR SEA WITH
EXPECTED 50 KT INTENSITIES.

MODEL DISCUSSION: MULTI MODEL GUIDANCE PORTRAYS A CROSS-TRACK
SPREAD OF UP TO 120 NM WITH THE WIDEST DIFFERENCE COMING BETWEEN
TAU 36 AND TAU 60 AS THE MODELS STRUGGLE TO RESOLVE THE HANDOFF OF
STEERING MECHANISMS BETWEEN THE NEAR-EQUATORIAL RIDGE AND
SUBTROPICAL RIDGING TO THE EAST AND SOUTH. NAVGEM TAKES THE SYSTEM
FURTHEST EAST WHILE GFS AND UKMO REMAIN MORE RESERVED, TAKING
SHARPER TURNS THAT KEEP TROPICAL CYCLONE FINA FIRMLY IN THE CENTRAL
TIMOR SEA. THE JTWC FORECASTED TRACK IS PLACED WITH THE MULTI-MODEL
CONSENSUS THROUGH TAU 36 AND BETWEEN THE MULTI MODEL CONSENSUS AND
NAVGEM FOR THE REMAINDER OF THE FORECAST PERIOD. INTENSITY GUIDANCE
ALSO VARIES IN MAXIMUM INTENSITY PEAKS AND THE BEGINNING OF THE
INITIAL WEAKENING PHASE, WITH GUIDANCE REFLECTING A SPREAD OF 50
KTS AFTER TAU 48. THE JTWC OFFICIAL FORECAST REMAINS CLOSE TO THE
MULTI MODEL CONSENSUS THROUGHOUT THE FORECAST. 

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