WDPS31 PGTW 060300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 10P (NAT)        
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.6S 161.3W
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 682 NM WEST OF PAPEETE, TAHITI
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 22 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED
LOW-LEVEL CIRCULATION (LLC) WITH DIMINISHED DEEP CONVECTION SHEARED
OVER THE EASTERN QUADRANT OF THE LLC. A 060013Z AMSR2 89 GHZ
MICROWAVE IMAGE REVEALS TIGHTLY CURVED DEEP CONVECTIVE BANDING OVER
THE NORTHERN AND EASTERN SEMICIRCLES, WITH THE LLC LOCATED ALONG
THE WESTERN EDGE OF THE CORE CONVECTION. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI AND THE AMSR2
MICROWAVE IMAGE. UPPER-LEVEL CONDITIONS REMAIN MARGINALLY FAVORABLE 
WITH LOW TO MODERATE NORTHWESTERLY VERTICAL WIND SHEAR OFFSET BY 
STRONG POLEWARD OUTFLOW. THE INITIAL INTENSITY IS ASSESSED AT 40 KTS 
AND IS HEDGED JUST BELOW THE SUBJECTIVE DVORAK INTENSITY ESTIMATES, 
BASED ON THE CONVECTIVE STRUCTURE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) POSITIONED
TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   PHFO: T3.0 - 45 KTS
   NFFN: T3.0 - 45 KTS
   CIMSS SATCON: 46 KTS AT 052020Z
   CIMSS ADT: 51 KTS AT 052340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 10P IS FORECASTED TO
TRACK EAST-SOUTHEASTWARD ALONG THE SOUTHERN PERIPHERY OF THE NER
THROUGH TAU 48. AFTER TAU 48, TC 10P WILL TURN EASTWARD TO EAST-
NORTHEASTWARD TOWARDS TAHITI AS THE NER REORIENTS. THE SYSTEM IS 
EXPECTED TO GRADUALLY INTENSIFY TO A PEAK INTENSITY OF 50 KTS BY
TAU 24 DUE TO THE STRONG POLEWARD OUTFLOW AND VERY WARM SST VALUES
(30-31 C). AFTER TAU 24, THE SYSTEM WILL WEAKEN QUICKLY DUE TO AN 
INCREASE IN VERTICAL WIND SHEAR (25-35 KTS) AND DRY AIR ENTRAINMENT. 

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 
80 NM CROSS-TRACK SPREAD AT TAU 72. THE 051800Z ECMWF AND GFS 
ENSEMBLES INDICATE A SIMILAR SPREAD IN SOLUTIONS AND SUPPORT THE JTWC 
FORECAST TRACK WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN FAIR 
AGREEMENT WITH A 15 KT SPREAD IN PEAK INTENSITY VALUES, WITH COAMPS-TC 
(NAVGEM VERSION) INDICATING A PEAK INTENSITY OF 55 KTS AT TAU 24. 

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