WDPS31 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (RUBY) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.1S 163.8E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 176 NM NORTHWEST OF NOUMEA, NEW CALEDONIA
   MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT DEEP
CONVECTION HAS ONCE AGAIN FLARED UP OVER THE ASSESSED CENTER, AND
HAS PERSISTED THROUGH THE 2000Z HOUR. SURFACE OBSERVATIONS FROM
KOUMAC, NEW CALEDONIA, INDICATES A RAPIDLY FALLING SURFACE
PRESSURE, NOW DOWN TO 984MB AND THE FIRST OUTER BANDS ARE NOW
STARTING TO BECOME VISIBLE ON THE NEW CALEDONIA RADAR. ALL THAT TO
SAY THAT WHILE THE LOW LEVEL CIRCULATION CENTER (LLCC) IS OBSCURED,
IT APPEARS THAT THE CENTER IS IN THE PROCESS OF MAKING LANDFALL
ALONG THE NORTHWESTERN TIP OF NEW CALEDONIA AT THE 2000Z HOUR. A
131640Z SSMIS 37GHZ MICROWAVE IMAGE DEPICTED AND SMALL BUT WELL
DEFINED MICROWAVE EYE, WHILE THE 89GHZ IMAGE CONFIRMED SOME
DOWNSHEAR TILT OF THE EYE FEATURE. THE INITIAL POSITION IS ASSESSED
WITH HIGH CONFIDENCE BASED ON AN EXTRAPOLATION OF THE MICROWAVE EYE
FEATURE. THE INITIAL INTENSITY OF 60 KNOTS IS ASSESSED WITH MEDIUM
CONFIDENCE, HEDGED SLIGHTLY HIGHER THAN THE OBJECTIVE DVORAK
ESTIMATES BASED ON THE SUBJECTIVE ADT AND SATCON ESTIMATES.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 69 KTS AT 132307Z
   CIMSS ADT: 63 KTS AT 131740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: MID-LEVEL DRY AIR ENTRAINMENT

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: AS DISCUSSED EARLIER, TC 03P IS IN THE PROCESS
OF MAKING A LANDFALL ALONG THE NORTHWEST TIP OF NEW CALEDONIA. THE
FORECAST CALLS FOR A TRACK ALONG THE SPINE OF NEW CALEDONIA, OR
JUST OFF THE EASTERN SHORELINE, THROUGH TAU 12, THEN A GRADUAL TURN
TO THE SOUTH INTO THE OPEN WATERS OF THE SOUTH PACIFIC TO THE NORTH
OF NEW ZEALAND. LATE ANIMATED EIR SUGGESTS THAT THE SYSTEM MAY BE
SLOWING DOWN A BIT AS IT MOVES OVER THE ISLAND AND THIS WILL APPLY
SOME UNCERTAINTY TO THE NEAR-TERM TRACK MOTION, BUT OVERALL NO
SIGNIFICANT CHANGE IS EXPECTED TO THE FORECAST TRACK, WHICH REMAINS
CONSISTENT WITH THE PREVIOUS FORECASTS. SHEAR CURRENTLY REMAINS
LOW, AND IS BEING OFFSET BY THE STRONG, DIVERGENT POLEWARD OUTFLOW
ALOFT. SOME SLIGHT EXCURSIONS ABOVE BELOW THE CURRENT INTENSITY CAN
BE EXPECTED IN THE NEXT 12 HOURS AS THE SYSTEM INTERACTS WITH LAND,
BUT OVERALL NO CHANGE IS FORECAST IN THE INTENSITY OVER THE NEXT 24
HOURS. AFTER TAU 24 WIND SHEAR WILL STEADILY INCREASES AS THE
SYSTEM BEGINS TO INTERACT WITH THE STRONG MID-LATITUDE WESTERLY
FLOW ALOFT WHILE MOVING OVER COOLER (24-25C) WATERS. BY TAU 36, THE
SYSTEM MOVES OVER WATERS LESS THAN 24C WHILE ENCOUNTERING VERY HIGH
SHEAR VALUES WHICH WILL SERVE TO ERODE THE TROPICAL CONVECTIVE
STRUCTURE AND MARK THE START OF SUBTROPICAL TRANSITION. THE SYSTEM
WILL TRANSITION TO A STORM-FORCE SUBTROPICAL LOW TO THE NORTH OF
NEW ZEALAND BY TAU 48.  

MODEL DISCUSSION: NUMERICAL TRACK GUIDANCE IS IN EXTREMELY GOOD
AGREEMENT, WITH MINIMAL SPREAD IN BOTH THE DETERMINISTIC AND
ENSEMBLE GUIDANCE, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST
TRACK. INTENSITY GUIDANCE SHOWS A BIT MORE UNCERTAINTY, WITH HWRF
INDICATING NEAR-TERM INTENSIFICATION TO 70 KNOTS WHILE THE
REMAINDER OF THE CONSENSUS MEMBERS SHOW MARGINAL WEAKENING THROUGH
TAU 24, FOLLOWED BY A RAPID WEAKENING AS THE SYSTEM GOES
SUBTROPICAL. DUE TO THE INTERACTION WITH LAND, THE OFFSETTING
ENVIRONMENTAL PARAMETERS AND THE RAPID TRANSLATION OF THE SYSTEM
SOUTHWARD INTO INCREASINGLY MARGINAL CONDITIONS, THE HWRF SOLUTION
IS DEEMED UNREALISTIC. THE JTWC FORECAST LIES SLIGHTLY LOWER THAN
THE CONSENSUS MEAN THROUGH THE FORECAST PERIOD WITH THE MEDIUM
CONFIDENCE. 

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