WDPS33 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 12P (TWELVE)
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9S 162.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 350 NM WEST-NORTHWEST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: EASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 12P (TWELVE) REVEALING A PARTIALLY EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH PERSISTENT DEEP CONVECTION OFFSET TO 
THE EAST OF THE ASSESSED LLCC OVER THE PAST SIX HOURS. A 072212Z 
METOP-B SCATTEROMETRY IMAGE REVEALED A FAIRLY ELONGATED CENTER OF 
CIRCULATION OF WEST-SOUTHWEST TO EAST-NORTHEAST ORIENTATION WITH 
HIGHEST OBSERVED WINDS IN THE SOUTHERN SEMICIRCLE OF TC 12P. A 
072208Z AMSR2 89GHZ SATELLITE MICROWAVE IMAGE CAPTURED FORMATIVE LOW 
LEVEL BANDING WRAPPING INTO A CONSOLIDATING LLCC WITH THE DEEP 
CONVECTION 60NM NORTHEAST. THE INITIAL POSITION IS PLACED WITH MEDIUM 
CONFIDENCE BASED ON THE AFOREMENTIONED SCATTEROMETRY AND MICROWAVE 
IMAGES. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM 
CONFIDENCE BASED ON THE AFOREMENTIONED SCATTEROMETRY DATA, AS WELL AS 
THE SUBJECTIVE INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NER TO THE NORTHEAST AND EXTENSION OF
THE STR TO THE SOUTH-SOUTWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   PHFO: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 12P IS FORECAST TO TRACK EAST-SOUTHEASTWARD
THROUGH TAU 12 AND THEN SOUTHEASTWARD THROUGH TAU 96. WARM (29-30C)
SEA SURFACE TEMPERATURES, INCREASING DIVERGENCE ALOFT, AND LOW TO
MODERATE (10-15KTS) VERTICAL WIND SHEAR (VWS) ARE ANTICIPATED TO 
ALLOW FOR GRADUAL INTENSIFICATION THROUGH TAU 48.  AFTER TAU 48, HIGH
(ABOVE 30 KTS) VWS AND DEGRADATION OF DIVERGENCE ALOFT ARE
ANTICIPATED TO CAUSE A GRADUAL INTENSITY DOWNTREND AS THE SYSTEM
TRACKS SOUTHEASTWARD TO TAU 96. EXPERIENCING THE STEERING INFLUENCE
OF A DEEP LAYER STR TO THE SOUTHEAST AT TAU 96, THE SYSTEM IS
ANTICIPATED TO TURN SHARPLY TO A WESTWARD TRACK AND MAINTAIN
THROUGH TAU 120.

MODEL DISCUSSION: GLOBAL NUMERICAL MODEL GUIDANCE IS IN GOOD
AGREEMENT THAT TC 12P WILL TRACK EAST-SOUTHEASTWARD THROUGH TAU 12
AND THEN SOUTHEASTWARD THROUGH TAU 96. THE TRACK CONSENSUS DISPLAYS
GOOD AGREEMENT BY TAU 72, WITH A NEGLIGIBLE ALONG-TRACK SPREAD AND
A CROSS-TRACK SPREAD OF 98NM. A GRADUAL RISE IN INTENSITY TO A PEAK
OF NEAR 50KTS BETWEEN TAU 36 AND TAU 48 IS OBSERVED IN MULTIPLE
GLOBAL MODELS. BETWEEN TAU 48 AND 96, MODEL GUIDANCE SUGGESTS A STR
BUILDS AHEAD OF TC 12P PROJECTED TRACK AND RECURVES THE TC NEAR TAU
96, CAUSING THE SYSTEM TO TURN WESTWARD AND MAINTAIN A WESTWARD
TRACK THROUGH TAU 120. THOUGH GLOBAL NUMERICAL GUIDANCE IS IN GOOD 
AGREEMENT REGARDING INTENSITY, THE JTWC INTENSITY CONSENSUS MEMBERS 
SHOW A LARGE DIVERGENCE BETWEEN OTHER MEMBERS (STATISTICAL-DYNAMICAL 
AND COUPLED MODELS), WITH A MAX INTENSITY SPREAD OF 55KTS EVIDENT AT 
TAU 72, CONTRIBUTING TO AN INTENSITY FORECAST CONFIDENCE OF LOW FROM 
TAU 00 TO TAU 120.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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