WDXS31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 26S (TWENTYSIX) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.5S 111.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 372 NM NORTH-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 26S HAS MAINTAINED INTENSITY OVER THE PAST 12 HOURS IN A
MARGINAL ENVIRONMENT CHARACTERIZED BY COMPETING INFLUENCES ON
STORM STRUCTURE AND DEVELOPMENT, INCLUDING FAVORABLY STRONG WESTWARD 
OUTFLOW ALOFT AND PASSAGE OVER VERY WARM WATER SUPPORTING THE CYCLONE 
AS PERSISTENT EASTERLY VERTICAL WIND SHEAR AND ENTRAINMENT OF DRIER 
AIR INTO THE EASTERN PORTION OF THE CIRCULATION HOLD THE SYSTEM IN 
CHECK. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP 
CONVECTION SHEARED TO THE WESTERN PERIPHERY OF A NEARLY FULLY EXPOSED 
LOW-LEVEL CIRCULATION. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON AN EXPOSED CENTER EVIDENT IN VISIBLE SATELLITE 
IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH 
CONFIDENCE BASED ON A CONSENSUS OF SUBJECTIVE DVORAK AND AUTOMATED 
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE AND OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED OVER WESTERN AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   CIMSS SATCON: 36 KTS AT 062324Z
   CIMSS ADT: 37 KTS AT 062300Z
   CIMSS AIDT: 35 KTS AT 070010Z
   CIMSS D-MINT: 28 KTS AT 062323Z
   CIMSS D-PRINT: 29 KTS AT 070010Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG WESTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT WITHIN THE EASTERN PORTION OF
THE CIRCULATION

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE FORECAST TRACK HAS SHIFTED ABOUT
30 NM TO THE SOUTH OF THE PREVIOUS FORECAST BASED ON RECENTLY 
OBSERVED STORM MOTION. HOWEVER, THERE ARE NO SIGNIFICANT CHANGES TO 
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC 26S WILL CONTINUE TO TRACK ALONG THE
NORTHWESTERN PERIPHERY OF THE CURRENT STEERING RIDGE THROUGH THE
ENTIRETY OF THE 48 HOUR FORECAST PERIOD. OFFSETTING ENVIRONMENTAL
INFLUENCES INCLUDING FAVORABLE WESTWARD OUTFLOW ALOFT AND PASSAGE
OVER WARM WATER AND UNFAVORABLE EASTERLY VERTICAL WIND SHEAR AND
DRIER AIR ENTRAINMENT ARE EXPECTED TO PERSIST IN THE NEAR-TERM, 
LEADING THE SYSTEM TO HOLD ITS PEAK INTENSITY AT THE WARNING 
THRESHOLD OF 35 KNOTS. HOWEVER, BY TAU 48, LOWER ALONG-TRACK SEA 
SURFACE TEMPERATURES AND SUSTAINED DRIER AIR ENTRAINMENT ARE EXPECTED 
TO EXERT SUFFICIENT INFLUENCE TO CAUSE DISSIPATION. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK FORECASTS ARE IN GOOD
AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO, WITH THE
GUIDANCE ENVELOPE BRACKETED BY THE NAVGEM ON THE SOUTHERN EDGE AND
GFS AND GEFS ON THE NORTHERN EDGE AND A 150 NM SPREAD BETWEEN
THESE SOLUTIONS AT TAU 48. THE REMAINDER OF THE GUIDANCE IS TIGHTLY
PACKED AROUND THE CONSENSUS AND THE CURRENT FORECAST, WHICH IS
PLACED WITH MEDIUM CONFIDENCE. MODEL INTENSITY FORECASTS ARE
TIGHTLY PACKED AND THE CONSENSUS HAS BEEN FAIRLY CONSISTENT OVER
THE PAST SEVERAL RUNS, LENDING HIGH CONFIDENCE TO THE CURRENT
INTENSITY FORECAST.

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