WDPS32 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 19P (NINETEEN) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.5S 177.7W
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 410 NM WEST OF PAGO PAGO
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CONSOLIDATING SYSTEM EMBEDDED WITHIN THE SOUTH PACIFIC CONVERGENCE
ZONE (SPCZ) WITH A STRONG DIVERGENT POINT SOURCE ALOFT AND CYCLICAL
DEEP CONVECTION OBSCURING THE CENTER OF THE CIRCULATION. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
AFOREMENTIONED PARITALLY OBSCURED EIR. THE INITIAL INTENSITY OF 35
KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 220941Z METOP-B
ASCAT IMAGE REVEALING A STREAK OF 35KT WIND SPEEDS TO THE NORTHEAST
OF THE CIRCULATION.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: ON THE SOUTHERN EXTENSION OF A NEAR
EQUATORIAL RIDGE (NER) TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   PHFO: T2.0 - 30 KTS

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 19P WILL BE DRIVEN
SOUTHWARD ON THE WESTERN PERIPHERY OF A NEAR EQUATORIAL RIDGE. THE
SYSTEM WILL CROSS THE RIDGE AXIS BETWEEN TAU 48-72, AND CONTINUE TO
ROUND THE RIDGE SOUTHEASTWARD FOR THE REMAINDER OF THE FORECAST
PERIOD. STRONG UPPER-LEVEL DIVERGENCE AND LOW VERTICAL WIND SHEAR
WILL SUPPORT INTENSIFICATION TO A PEAK OG 75KTS BY TAU 48. AFTER
TAU 72, THE SYSTEM WILL TRACK OVER UNFAVORABLE SEA SURFACE
TEMPERATURES BELOW 26C. COUPLED WITH AN APPROACHING UPPER-LEVEL
TROUGH, SUBTROPICAL TRANISITION WILL BEGIN AND COMPLETE BETWEEN TAU
72-96 AS THE SYSTEM WEAKENS TO 55KTS AS HIGH VERTICAL WIND SHEAR
INCREASES.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL TRACK SOUTHWARD AND THEN SOUTHEASTWARD FOR THE
REMAINDER OF THE FORECAST PERIOD. THE CROSS-TRACK SPREAD BY TAU 96
IS 78NM. THE JTWC INTENSITY GUIDANCE HAS A LARGER SPREAD OF
SOLUTIONS BETWEEN A PEAK OF 65KTS (HAFS-A) TO 100KTS (HWRF).
DIFFERENT TRACK SPEEDS INFLUENCE THE VARIETY OF TIME SPENT IN
FAVORABLE CONDITIONS FOR INTENSIFICATION. THE JTWC FORECAST LIES
CLOSELY TO THE CONSENSUS MEAN.

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