WDXS31 PGTW 072100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02S (TERATAI) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.8S 106.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 766 NM NORTHWEST OF LEARMONTH, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS FLARING DEEP 
CONVECTION SHEARED TO THE WEST OF A PARTIALLY EXPOSED LOW LEVEL 
CIRCULATION CENTER (LLCC). THE CONVECTION AT ANALYSIS TIME WAS 
HIGHLY SYMMETRICAL AND LOCATED IN CLOSE VICINITY TO THE LLCC, 
HOWEVER SUBSEQUENT IMAGERY INDICATES A VERY SHARP UPSHEAR EDGE OF 
THE CIRRUS SHIELD AND AN INCREASINGLY RAGGED, DISORGANIZED 
STRUCTURE. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE 
BASED ON THE PARTIALLY EXPOSED LLCC IN ANIMATED SHORTWAVE INFRARED 
IMAGERY. WHILE THE CONVECTIVE STRUCTURE IS NOT ALL THAT IMPRESSIVE, 
THE LOW LEVEL WIND FIELD AS MEASURED BY A SERIES OF SCATTEROMETER 
PASSES BETWEEN 071145Z AND 111516Z SHOWING 30-35 KNOT WINDS 
SURROUNDING THE LLCC. THUS THE INITIAL INTENSITY IS ASSESSED AT 35 
KNOTS, HEDGED ABOVE THE PGTW T1.5 (25-30 KTS) DVORAK CURRENT 
INTENSITY ESTIMATE FROM PGTW, WHICH IS BASED SOLELY UPON THE 
DISORGANIZED CONVECTIVE STRUCTURE. THE SYSTEM IS MOVING SOUTHWARD 
ALONG THE NORTHWESTERN PERIPHERY OF A LOW TO MID-LEVEL SUBTROPICAL 
RIDGE (STR) TO THE SOUTHEAST. THE ENVIRONMENT IS SOMEWHAT MARGINAL, 
WITH WARM (28-29C) SSTS AND GOOD POLEWARD OUTFLOW OFFSETTING 
MODERATE VWS. 

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF STR CENTERED TO 
THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE TO HIGH EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY FOR THE RE-START OF 
WARNINGS ON TC 02S.

FORECAST DISCUSSION: TROPICAL CYCLONE 02S (TERATAI) HAS RE-
INTENSIFIED TO TROPICAL STORM STRENGTH AND THUS JTWC IS RECOMMENCING 
ISSUANCE OF TROPICAL CYCLONE WARNINGS. TC 02S IS FORECAST TO TURN 
SOUTHWESTWARD OVER THE NEXT 12 HOURS, THEN CONTINUE TRACKING 
SOUTHWESTWARD THROUGH THE FORECAST PERIOD ALONG THE NORTHWESTERN 
PERIPHERY OF A LOW TO MID-LEVEL STR TO THE SOUTHEAST. BETWEEN 
071200Z AND 071800Z, THE UPPER-LEVEL SHEAR ENVIRONMENT WEAKENED TO 
THE POINT WHERE THE CORE OF THE SYSTEM WAS ABLE TO STACK VERTICALLY, 
AND CONVECTION FLARED OVER TOP OF THE LLCC. SUBSEQUENTLY, SHEAR HAS 
INCREASED ONCE AGAIN AS EVIDENCED BY THE VERY SHARP UPSHEAR 
(EASTERN) EDGE OF THE CONVECTIVE MASS, AND THE EXPOSED LLCC. GLOBAL 
MODEL FIELDS SUGGEST THE SHEAR WILL AVERAGE ABOUT 15 KNOTS FOR THE 
NEXT 24-48 HOURS. HOWEVER, THIS MODERATE SHEAR WILL COMPETE WITH, 
AND BE OFFSET BY, RELATIVELY GOOD POLEWARD OUTFLOW, RESULTING IN A 
STEADY INTENSITY THROUGH TAU 36. BEGINNING AROUND TAU 36 THE OUTFLOW 
PATTERN SHIFTS AND UPPER-LEVEL FLOW BECOMES CONVERGENT OVER TOP OF 
THE SYSTEM AND THE MID-ATMOSPHERE BEGINS TO DRY OUT, LEADING TO 
WEAKENING AND DISSIPATION NO LATER THAN TAU 48.   

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE IS IN GOOD AGREEMENT, 
WITH ALL CONSENSUS MEMBERS AGREEING ON THE SOUTHWESTWARD TRACK, 
ENSCONCED WITHIN A 100-120NM ENVELOPE, LENDING HIGH CONFIDENCE TO 
THE JTWC FORECAST TRACK. INTENSITY GUIDANCE IS IN OVERALL GOOD 
AGREEMENT, WITH THE MAJORITY OF CONSENSUS MEMBERS INDICATING A FLAT 
INTENSITY TREND, LENDING HIGH CONFIDENCE TO THE JTWC INTENSITY 
FORECAST. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: HIGH//
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