WDPS33 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (FIFTEEN) WARNING 
NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.8S 163.3W
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 284 NM NORTHWEST OF RAROTONGA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) THAT IS
APPROACHING A MID-LATITUDE FRONTAL ZONE ON THE NORTHEASTERN FLANK
OF AN UPPER-LEVEL TROUGH. A 1929Z GMI MICROWAVE PASS AND A 2356Z
ATMS MICROWAVE PASS SHOW THAT TIGHT CONVECTIVE BANDING EXISTS NEAR
THE LLCC BUT IS ONLY WRAPPING AROUND THE NORTHERN AND EASTERN
SIDES, LIKELY DUE TO MODERATE SOUTHWESTERLY SHEAR. THE INITIAL
INTENSITY IS SET AT 40 KTS BASED ON A BLEND OF AGENCY DVORAK
ESTIMATES AND OBJECTIVE SATELLITE INTENSITY ESTIMATES FROM CIMSS.
STRONG POLEWARD OUTFLOW IS EVIDENT IN SATELLITE IMAGERY TOWARDS THE
JET STREAK TO THE SOUTHEAST OF THE CYCLONE. AITUTAKI ISLAND ABOUT
210 NM TO THE EAST-SOUTHEAST HAS BEEN OBSERVING SUSTAINED
NORTHEASTERLY WINDS OF 21-22 KT DURING THE PAST FEW HOURS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 35 KTS AT 152340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE 15P IS ACCELERATING
SOUTHEASTWARD AS IT APPROACHES A FRONTAL BOUNDARY AND UPPER-LEVEL
TROUGH TO THE SOUTH. THIS WILL INITIATE THE PROCESS OF
EXTRATROPICAL TRANSITION IN ABOUT 12 HOURS AS VERTICAL SHEAR AND
BAROCLINICITY DRAMATICALLY INCREASE. GLOBAL MODELS ARE IN GOOD
AGREEMENT THAT 15P WILL BECOME A FRONTAL CYCLONE IN ABOUT 36 HOURS.
THE INTENSITY FORECAST SHOWS POTENTIAL FOR A SLIGHT INCREASE IN
MAXIMUM WINDS TO AROUND 45 KT DUE TO BAROCLINIC ENHANCEMENT OF THE
WIND FIELD, WHICH DYNAMICAL MODELS ALSO AGREE ON.

MODEL DISCUSSION: DYNAMICAL MODELS ARE IN TIGHT AGREEMENT ON THE
TRACK AND INTENSITSY FORECASTS, AND THE JTWC FORECAST IS CLOSE TO
THE MULTI-MODEL CONSENSUS.

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