WDPS31 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 15P (JUDY) 
WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.4S 172.4E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 350 NM EAST OF NOUMEA, NEW CALEDONIA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH TIGHTLY WRAPPING
LOW LEVEL CLOUD LINES EXPOSED IN THE WESTERN SEMICIRCLE. A MUCH
NEEDED 012207Z ASCAT-B SCATTEROMETRY PASS REVEALED A SYMMETRIC
CIRCULATION WITH TWO PRIMARY FIELDS OF HIGHER WINDS TO THE WEST AND
EAST OF THE LLCC. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE PARTIALLY EXPOSED NATURE IN MSI. THE
INITIAL INTENSITY OF 90 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON ALL AGENCY DVORAK INTENSITY ESTIMATES AND CIMMS AUTOMATED
ESTIMATES REFLECTING T5.5-T6.0 RANGE DUE TO CONSTRAINTS WHILE THE
CURRENT INTENSITY ESTIMATES ARE CLOSER TO 90 KTS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
EAST-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   KNES: T6.0 - 115 KTS
   PHFO: T5.5 - 102 KTS
   CIMSS SATCON: 102 KTS AT 012026Z
   CIMSS ADT: 107 KTS AT 012330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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: TC 15P (JUDY) IS FORECAST TO CONTINUE ON ITS
SOUTHEASTWARD TRACK AS IT PROGRESSES ALONG THE OUTER PERIPHERY OF
THE STR TO THE EAST-NORTHEAST. AS 15P TRANSITS POLEWARD, IT WILL BE
IN AN INCREASINGLY HOSTILE ENVIRONMENT CHARACTERIZED BY STRONGER
VWS, AND INCREASING DRY AIR ENTRAINMENT, THESE FACTORS WILL
CONSPIRE TO WEAKEN THE SYSTEM TO AROUND 70 KTS BY TAU 24. AFTER TAU
24, THE SYSTEM WILL BEGIN ITS SUBTROPICAL TRANSITION (STT) AND A
FURTHER DECREASE IN INTENSITY TO 55 KTS IS ANTICIPATED AS THE
SYSTEM CROSSES THE 26 C ISOTHERM. BY TAU 36, 15P WILL CONTINUE ITS
STT AND WILL CONTINUE TO FEEL THE EFFECTS OF DRY AIR ENTRAINMENT
FROM THE NORTHWEST BEING WRAPPED INTO THE CENTER. BY TAU 48, 15P
WILL HAVE WEAKENED TO AROUND 50 KTS AND BECOME FULLY SUBTROPICAL.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT THAT 15P
WILL TRANSIT POLEWARD OF THE STR AND BY TAU 48 THE SYSTEM WILL
ACCELERATE EAST-SOUTHEASTWARD AS A SUBTROPICAL SYSTEM. THERE IS A
SLIGHT SPREAD IN MODEL OUTPUT BY TAU 48 RESULTING IN AN OVERALL
MEDIUM CONFIDENCE IN THE TRACK FORECAST. RELIABLE MODEL INTENSITY
GUIDANCE IS IN GOOD AGREEMENT WITH ALL MEMBERS INDICATING A
WEAKENING TREND THROUGH THE FORECAST PERIOD. FOR THIS REASON THE
JTWC INTENSITY FORECAST IS PLACED WITH HIGH CONFIDENCE.

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