WDXS31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (TWENTYNINE) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.4S 73.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 268 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE (TC) 29S WITH AN EXPANDING CENTRAL DENSE OVERCAST AND SPIRAL
BANDS OF DEEP CONVECTION WRAPPING INTO THE CENTER. 29S HAS 
CONSOLIDATED CONSIDERABLY OVER THE PAST FEW HOURS; A 020110Z SSMIS 
91GHZ IMAGE REVEALS A SLIGHTLY ELONGATED BUT COMPACT CIRCULATION WITH 
DEEP CONVECTION SURROUNDING THE CORE. ENVIRONMENTAL ANALYSIS REVEALS A 
HIGHLY FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW (5-10 KTS) VERTICAL 
WIND SHEAR, HIGH (29-30 C) SEA SURFACE TEMPERATURES, AND ROBUST NEAR-
RADIAL OUTFLOW. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE 
BASED ON A 012239Z SSMIS 91GHZ IMAGE AND THE AFOREMENTIONED 020110Z 
91GHZ SSMIS IMAGE. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH 
HIGH CONFIDENCE BASED ON A PARTIAL 011957Z AMSR2 WIND SPEED IMAGE 
REVEALING 30-35KTS OUTSIDE RAIN CONTAMINATED REGIONS, THE CIMSS DPRINT 
AUTOMATED INTENSITY ESTIMATE, AND AGENCY SUBJECTIVE DVORAK FIXES 
LISTED BELOW.

INITIAL WIND RADII BASIS: NORTHEASTERN AND SOUTHEASTERN QUADRANT
WIND RADII BASED ON A PARTIAL 011957Z AMSR2 WIND SPEED IMAGE.

CURRENT STEERING MECHANISM: A DEEP LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE SOUTHEAST OF THE SYSTEM

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   FMEE: T2.5 - 35 KTS
   CIMSS D-PRINT: 33 KTS AT 020000Z
   CIMMS D-MINT: 30 KTS AT 020110Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

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 29S IS FORECAST TO TRACK ALONG THE
NORTHWESTERN PERIPHERY OF THE STEERING STR CENTERED TO ITS
SOUTHEAST FOR THE NEXT 48 HOURS. BETWEEN TAU 48-72, 29S WILL BEGIN
TRANSITING SOUTHWARD AS IT APPROACHES THE RIDGE AXIS. 29S IS
FORECAST TO ROUND THE RIDGE AXIS AROUND TAU 72 AND ACCELERATE
SOUTHEASTWARD, BEGINNING SUBTROPICAL TRANSITION (STT) NO LATER THAN
TAU 96. STT IS FORECAST TO BE COMPLETE BY TAU 120, AS 29S ENTERS
INTO A HOSTILE ENVIRONMENT CHARACTERIZED BY UNFAVORABLE SEA SURFACE
TEMPERATURES, DRY AIR, AND INCREASING VERTICAL WIND SHEAR AS THE
STORM BEGINS TO INTERACT WITH THE UPPER-LEVEL JET. REGARDING
INTENSITY, 29S IS FORECAST TO STEADILY INTENSIFY THROUGH TAU 12,
WITH A PERIOD OF RAPID INTENSIFICATION (RI) EXPECTED FROM TAU 12-36. 
29S IS EXPECTED TO CONTINUE INTENSIFYING PAST TAU 36, ALBEIT AT A
SLOWER RATE, UNTIL IT PEAKS AT APPROXIMATELY THE SAME TIME IT
ROUNDS THE RIDGE AXIS. THE PEAK INTENSITY IS FORECAST TO BE 80 KTS
AT TAU 48-72, HOWEVER, A PEAK INTENSITY HIGHER THAN 80 KTS IS
ANTICIPATED NEAR TAU 60, WHICH IS UNABLE TO BE REFLECTED ON THE
JTWC FORECAST. AFTER TAU 72, 29S IS FORECAST TO STEADILY WEAKEN AS
IT TRACKS INTO AN UNFAVORABLE ENVIRONMENT AND UNDERGOES STT.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH THE FIRST 72 HOURS OF THE FORECAST, WITH ALL
RELIABLE MODELS DEPICTING A SOUTH-SOUTHWEST TRACK THROUGH TAU 72. 
AROUND TAU 72 AND FOR THE REMAINDER OF THE FORECAST PERIOD, MODEL 
GUIDANCE DIVERGES SLIGHTLY AS 29S ROUNDING THE RIDGE AXIS AND 
UNDERGOING STT INTRODUCES UNCERTAINTY TO TRACK SPEED. AS A RESULT, THE 
JTWC TRACK FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE. RELIABLE
INTENSITY AIDS ARE IN GENERALLY GOOD AGREEMENT IN A PERIOD OF
SIGNIFICANT INTENSIFICATION WITHIN THE NEXT 48 HOURS, THERE IS
DISAGREEMENT IN THE RATE OF INTENSIFICATION, AND THEREFORE THE PEAK
INTENSITY. TWO JTWC RI AIDS, HWRF, AND GFS INDICATE THE POSSIBILITY
OF RI, WHILE HAFS-A REMAINS MORE CONSERVATIVE. ALL INTENSITY
GUIDANCE SUPPORTS AN INTENSITY OF AT LEAST 75 KTS AT TAU 60,
HOWEVER, THE RI AIDS AND HWRF EXCEED A 100KT PEAK INTENSITY AT TAU
60. ALL INTENSITY MODELS ARE IN AGREEMENT IN A STEADY WEAKENING
TREND FROM TAU 60-72 THROUGH THE END OF THE FORECAST PERIOD. THE
JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE MULTI-MODEL
CONSENSUS WITH OVERALL MEDIUM CONFIDENCE.

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