WDXS31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 25S (TWENTYFIVE) 
WARNING NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.7S 113.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 652 NM NORTH-NORTHWEST OF PORT HEDLAND,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 19 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A QUICKLY
MOVING LOW-LEVEL CIRCULATION CENTER (LLCC), WITH CONVECTION
DISLOCATED WESTWARD OF THE SURFACE CENTER. THE ENVIRONMENT REMAINS
MARGINALLY UNFAVORABLE WITH HIGH VERTICAL WIND SHEAR (30+ KTS), SEA
SURFACE TEMPERATURES BETWEEN 28 C TO 29 C, AND MODERATE WESTWARD
OUTFLOW ALOFT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON AN EARLIER 042210Z RCM-1 SAR PASS AND ANIMATED MSI. THE
INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE PREVIOUSLY MENTIONED 042210Z RCM-1 SAR DATA ACCOUNTING
FOR STRONG GRADIENT WESTERLY FLOW LOCATED IN THE NORTHERN QUADRANT.

INITIAL WIND RADII BASIS: 042210Z SAR DATA 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) POSITIONED
TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   CIMSS ADT: 34 KTS AT 042030Z
   CIMSS AIDT: 32 KTS AT 042030Z
   CIMSS D-PRINT: 29 KTS AT 042300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 30+ KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 25S WILL CONTINUE ON ITS
EASTWARD TRACK UNTIL JUST BEFORE TAU 12. AFTERWARDS, TC 25S WILL
MAKE A GRADUAL PUSH SOUTHEASTWARD AS THE CIRCULATION TRACKS ALONG
THE SOUTHERN PERIPHERY OF THE NER TO THE NORTH. INTERACTION WITH
THE WIND FIELD OF A SEPARATE DEVELOPING TROPICAL CYCLONE (93S) IS
STILL EXPECTED, CAUSING A SHARPER SOUTHEASTWARD TURN AND EVENTUALLY
STALLING THE MOTION OF THE CYCLONE WEST OF BROWSE ISLAND. TC 25S IS
FORECASTED TO MAINTAIN ITS INTENSITY OVER THE NEXT 12 HOURS WHILE
CONTINUING TO BATTLE VERY STRONG AND UNFAVORABLE EASTERLY VERTICAL
WIND SHEAR, TILTING THE VORTEX WESTWARD. DRY-AIR ENTRAINMENT
FROM THE SOUTH AND WEST IS FORECASTED TO SHALLOW OUT THE SYSTEM
THROUGHOUT THE FORECAST PERIOD, INITIATING A TERMINAL WEAKENING
PHASE IN THE NEAR TERM. 25S IS EXPECTED TO DISSIPATE NEAR TAU 36,
NORTH-NORTHWEST OF THE DAMPIER PENINSULA.

MODEL DISCUSSION: CROSS-TRACK SPREAD AMONGST NUMERICAL MODEL TRACK
REMAINS UNDER 80 NM THROUGHOUT THE FORECAST PERIOD, SHOWING A
CONTINUING HIGH CONFIDENCE IN THE CONTINUED SOUTHEASTWARD TRACK.
THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL
CONSENSUS THROUGHOUT THE FORECAST PERIOD WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS SPREAD UP TO 15 KTS AT TAU 36. THE MAJORITY
OF THE GUIDANCE IS ALIGNED ON STEADY SURFACE INTENSITIES THROUGH
TAU 12, FOLLOWED BY A WEAKENING TREND THEREAFTER. THE JTWC
INTENSITY FORECAST IS PLACED NEAR THE MULTI-MODEL INTENSITY
CONSENSUS WITH HIGH CONFIDENCE. 

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