WDPS31 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02P (TWO) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 10.0S 170.8E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 484 NM NORTH-NORTHEAST OF PORT VILA,
VANUATU
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CONSOLIDATING SYSTEM WITH SPIRAL BANDS OF DEEP CONVECTION WRAPPING
INTO A PERSISTENT CLOUD STRUCTURE, OBSCURING THE LOW-LEVEL
CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON ANIMATED MSI IMAGERY. A PARTIAL 1122208Z
ASCAT-B SHOWS A SWATH OF 30-35 KNOT WINDS OVER THE NORTHEASTERN
SEMICIRCLE WITH WEAKER WINDS OVER THE CENTER AND SOUTHEASTERN
SEMICIRCLE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE IMPROVING CONVECTIVE STRUCTURE AS WELL AS A
COMBINATION OF AGENCY DVORAK INTENSITY ESTIMATES RANGING BETWEEN
T2.0 TO T2.5 AND THE AFOREMENTIONED ASCAT-B PASS, WHICH SHOWS UP TO
30-35 KNOTS ON THE NORTHEASTERN QUADRANT. THE OVERALL ENVIRONMENT
IS ASSESSED AS FAVORABLE BASED ON MODERATE RADIAL OUTFLOW, LOW TO
MODERATE (10-15 KNOTS) VERTICAL WIND SHEAR (VWS) AND WARM (29-30C)
SEA SURFACE TEMPERATURES (SSTS).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 02P IS FORECAST TO TRACK SOUTHWESTWARD AND
TRANSIT THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE EAST OF
AMERICAN SAMOA AS THE CYCLONE NEARS THE ISLAND OF FIJI.
ENVIRONMENTAL CONDITIONS OVER THE NEXT 48 HOURS WILL REMAIN
FAVORABLE, CHARACTERIZED BY WARM SEA SURFACE TEMPERATURES (SSTS)
(29-30C), MODERATE RADIAL DIVERGENCE ALOFT AND LOW-MODERATE
VERTICAL WIND SHEAR (VWS) (10-15 KNOTS). THESE FAVORABLE CONDITIONS
WILL FUEL STEADY INTENSIFICATION TO ALLOW TC 02P TO REACH A
POTENTIAL MAXIMUM INTENSITY OF 55 KNOTS, POSSIBLY HIGHER, BETWEEN
TAU 36 AND TAU 48. HOWEVER, BY TAU 72, INCREASING VWS AND DRY AIR
ENTRAINMENT WILL BEGIN TO WEAKEN THE SYSTEM. ADDITIONALLY, 02P WILL
BEGIN SUBTROPICAL TRANSITION AS THE SYSTEM CROSSES POLEWARD OF THE
26C ISOTHERM ALONG WITH HIGH VWS ASSOCIATED WITH THE SUBTROPICAL
JET. BY TAU 120, TC 02P IS EXPECTED TO TRANSITION TO AN ASYMMETRIC
WARM CORE WITH AN EXPANSIVE WIND FIELD.

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE IS IN
GOOD AGREEMENT WITH A 170NM SPREAD IN SOLUTIONS AT TAU 72, LENDING
HIGH CONFIDENCE TO THE JTWC FORECAST TRACK. THE JTWC FORECAST
FOLLOWS CLOSE TO THE MULTI-MODEL CONSENSUS THROUGHOUT THE FORECAST
PERIOD. THE INTENSITY GUIDANCE IS IN GOOD AGREEMENT WITH ALL
MEMBERS SHOWING STEADY INTENSIFICATION THROUGH TAU 48 WITH THE
POSSIBILITY FOR A HIGHER PEAK INTENSIFICATION INDICATED BY
COAMPS-TC (COTI) WHICH PEAKS NEAR 70 KNOTS BY TAU 36. AFTER TAU 48,
ALL INTENSITY MODELS SHOW A GRADUAL DECREASING INTENSITY TREND
THROUGH THE END OF THE FORECAST. THUS, THE JTWC INTENSITY FORECAST
IS PLACED WITH MEDIUM CONFIDENCE.

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