WDPS31 PGTW 122100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (RUBY) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.4S 158.8E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 536 NM NORTHWEST OF NOUMEA, NEW CALEDONI
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS WELL
DEFINED SPIRAL BANDS OF DEEP CONVECTION, WRAPPING INTO A DEVELOPING
EYE FEATURE. WHILE THE LOW LEVEL CIRCULATION CENTER (LLCC) IS
CURRENTLY OBSCURED, THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON THE CONGRUENCE OF AGENCY FIX POSITIONS,
EXTRAPOLATION OF A VERY WELL-DEFINED MICROWAVE EYE FEATURE IN A
121440Z GPM 37GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 65
KNOTS HIGH CONFIDENCE BASED ON AN AVERAGE OF THE AGENCY DVORAK
CURRENT INTENSITY ESTIMATES AND NEAREST THE SATELLITE CONSENSUS
ESTIMATE. TC 03P IS RAPIDLY INTENSIFYING UNDER FAVORABLE
ENVIRONMENTAL CONDITIONS OF LOW VWS, WARM SSTS AND VERY STRONG
OUTFLOW ALOFT, PROVIDED BY A POINT SOURCE OVER TOP OF THE SYSTEM,
AND A TAP INTO DIFFLUENT POLEWARD OUTFLOW INTO THE BASE OF A DEEP
TROUGH EAST OF AUSTRALIA.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   KNES: T4.5 - 77 KTS
   ABRF: T3.5 - 55 KTS
   CIMSS SATCON: 64 KTS AT 121449Z
   CIMSS ADT: 61 KTS AT 121740Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 03P IS FORECAST TO TRACK SOUTHEASTWARD
THROUGH THE ENTIRE FORECAST PERIOD, ALONG THE SOUTHWESTERN
PERIPHERY OF THE DEEP STR CENTERED TO THE EAST. THE SYSTEM IS
EXPECTED TO SKIRT THE EASTERN COAST OF NEW CALEDONIA OVER THE NEXT
24 TO 36 HOURS BEFORE MOVING INTO THE OPEN WATERS OF THE SOUTH
PACIFIC. THE SYSTEM IS FORECAST TO STEADILY ACCELERATE ALONG THE
SOUTHEASTWARD TRACK ALONG THE STRONG GRADIENT BETWEEN THE STR AND A
DEEP, HIGH-AMPLITUDE TROUGH TO THE WEST. TC 03P IS FORECAST TO
CONTINUE TO RAPIDLY INTENSIFY FOR ANOTHER 24 HOURS, REACHING A PEAK
OF 85 KNOTS BY TAU 24. AFTER TAU 24, MID-LEVEL DRY AIR WILL BEGIN
TO ENCROACH UPON THE CORE OF TC 03P, AND COMBINED WITH STEADILY
INCREASING VWS, WILL BEGIN A LONG WEAKENING TREND THAT CONTINUES
THROUGH THE END OF THE FORECAST. BETWEEN TAU 48 AND 72, THE SYSTEM
WILL BEGIN TO FEEL THE EFFECTS OF THE STRONG MID-LATITUDE WESTERLY
FLOW AND BEGIN MOVING OVER COOLER SSTS, SUPPORTING ADDITIONAL
WEAKENING AND EROSION OF THE CONVECTIVE CORE. BY TAU 72 THE SYSTEM
WILL BEGIN SUBTROPICAL TRANSITION AS VWS INCREASES DRAMATICALLY AND
SSTS DROP PRECIPITOUSLY AND IS EXPECTED TO FULLY TRANSITION INTO A
STORM-FORCE SUBTROPICAL LOW TO THE NORTHEAST OF NEW ZEALAND. 

MODEL DISCUSSION: TRACK GUIDANCE CONTINUES TO BE TIGHTLY PACKED
THROUGH THE FORECAST PERIOD, WITH CROSS-TRACK SPREAD OF LESS THAN
100NM AT TAU 48, INCREASING TO 200NM BY TAU 96. HOWEVER,
ALONG-TRACK SPREAD INCREASES AFTER TAU 48, TO OVER 200NM AS THE
ECMWF AND NAVGEM IN PARTICULARLY BEGIN TO LAG THE REMAINDER OF THE
GUIDANCE AS THE SYSTEM STARTS SUBTROPICAL TRANSITION. GFS AND ECMWF
ENSEMBLE GUIDANCE ARE ALSO IN GOOD AGREEMENT, PARTICULARLY THROUGH
TAU 96, WITH MODEST SPREAD THEREAFTER. INTENSITY GUIDANCE IS MIXED,
WITH THE GFS AND HWRF SHOWING NEAR-TERM WEAKENING FOLLOWED BY
MODEST RE-INTENSIFICATION TO A PEAK LESS THAN 60 KNOTS. AT THE SAME
TIME HOWEVER THE GFS AND NAVGEM SHIPS GUIDANCE IS BULLISH, WITH A
PEAK BETWEEN 80-85 KNOTS. ADDITIONALLY, THE RAPID INTENSITY
PREDICTION AID (RIPA) IS CONTINUING TO BE TRIGGERED, WITH A PEAK AS
HIGH AS 105 KNOTS BY TAU 24. ALL OF WHICH INDICATES A FAIRLY HIGH
AMOUNT OF UNCERTAINTY IN THE ULTIMATE PEAK INTENSITY OF TC 03P. THE
JTWC INTENSITY FORECAST CLOSELY TRACKS THE SHIPS GUIDANCE, AND 15
KNOTS ABOVE THE CONSENSUS THROUGH THE FORECAST, 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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