WDPS31 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.6S 155.7E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 584 NM SOUTH OF KAPINGAMARANGI
   MOVEMENT PAST 6 HOURS: WESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) IMAGERY REVEALS A 10 NM DIAMETER
EYE FEATURE OF TROPICAL CYCLONE (TC) 30P (MAILA) PROVIDING HIGH
FIDELITY FOR THE INITIAL POSITION. THE INITIAL INTENSITY OF 105 KTS
IS ASSESSED WITH MODERATE CERTAINTY, REPRESENTING A CONSENSUS OF
AGENCY DVORAK FIXES AND OBJECTIVE AUTOMATED ESTIMATES LISTED BELOW. 
THE SYSTEM EXHIBITS ALTERNATING PERIODS OF MINOR WEAKENING AND
STRENGTHENING AS EVIDENCED BY THE MEASUREMENTS OF THE EYE TEMPERATURE 
SINCE LAST WARNING, GOING FROM -16 C AT 080600Z, WARMING TO -3 C AT 
080900Z AND THEN COOLING AGAIN TO -19 C AT CURRENT TAU. ENVIRONMENTAL 
ANALYSIS REVEALS MAINLY FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW 
VERTICAL WIND SHEAR (10-15 KTS), SUFFICIENT DEEP-LAYER MOISTURE, AND A 
WELL-DEFINED WESTWARD-ORIENTED UPPER-LEVEL OUTFLOW CHANNEL. THE 
PRIMARY MITIGATING FACTOR WITH THE POTENTIAL TO ARREST THE 
INTENSIFICATION PROCESS IS A NEGATIVE OCEANIC FEEDBACK VIA AN 
UPWELLING-INDUCED COLD WAKE, A FEATURE PROMINENTLY SIMULATED BY THE 
HAFS AND HWRF COUPLED MODELS. THE PROJECTED COLD POOL IS CO-LOCATED 
AHEAD OF THE CURRENT FORECAST TRACK. AT PRESENT, THE OBSERVED 
STRUCTURAL CONDITION SUGGESTS THIS THERMODYNAMIC INHIBITOR IS NOT YET 
A DOMINANT FACTOR.

INITIAL WIND RADII BASIS: A 081053 METOP-C ASCAT PASS

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO
THE SOUTHWEST AND CENTERED OVER AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   ABRF: T5.5 - 102 KTS
   CIMSS ADT: 122 KTS AT 081130Z
   CIMSS AIDT: 108 KTS AT 081130Z
   CIMSS D-PRINT: 89 KTS AT 081230Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 30P IS EXPECTED TO MAINTAIN A SLOW (3-4
KTS) GENERALLY WESTWARD PROPAGATION OVER THE NEXT 24 HOURS.
SUBSEQUENTLY, A GRADUAL ACCELERATION TOWARD THE WEST-SOUTHWEST IS
ANTICIPATED AND DRIVEN BY THE REPOSITIONING OF A DEEP-LAYER RIDGE 
CENTERED TO THE SOUTH OF THE SYSTEM. THIS PROJECTED TRAJECTORY 
MAINTAINS TC 30P ON A COURSE JUST SOUTH OF THE PAPUAN PENINSULA, WITH 
POTENTIAL FRICTIONAL EFFECTS DRIVEN BY THE LAND INTERACTION. AFTER TAU 
72, TC MAILA WILL TURN WESTWARD AGAIN, AS THE RIDGING BUILDS FURTHER 
AND STEERS THE SYSTEM TOWARDS THE MOSTLY FLAT CAPE YORK PENINSULA,
AUSTRALIA. CONFIDENCE IN THE INTENSITY FORECAST REMAINS LOW, A
DIRECT CONSEQUENCE OF THE AFOREMENTIONED UPWELLING POTENTIAL. THE
COUPLED MODELS CONTINUE TO DEPICT A SIGNIFICANT OCEANIC COLD WAKE
(BELOW 26 C) DIRECTLY ALONG THE FORECAST PATH, WHICH WOULD TYPICALLY
LEAD TO A CESSATION OF INTENSIFICATION. HOWEVER, THE OBSERVED
PERSISTENT DEEPENING SUGGESTS THE COLD POOL MAY BE LESS EXTENSIVE
OR THAT AMBIENT SEA SURFACE TEMPERATURES ARE WARMER THAN MODELED.
GIVEN THE OTHERWISE CONDUCIVE ATMOSPHERIC AND OCEANIC PARAMETERS.
SLIGHT, BUT PERSISTENT INTENSIFICATION IS FORECAST, WITH A PEAK
INTENSITY OF APPROXIMATELY 110-115 KTS PROJECTED BETWEEN TAU 12 AND
TAU 24. THEREAFTER, A STEADY DECAY PHASE IS EXPECTED TO BEGIN,
DRIVEN BY INCREASING MID-LEVEL VERTICAL WIND SHEAR (PROJECTED TO
REACH 35 KTS AROUND TAU 72) AND THE POTENTIAL FOR LAND INDUCED
FRICTIONAL WEAKENING FROM THE OWEN STANLEY RANGE, PAPUA NEW GUINEA.

MODEL DISCUSSION: SHORT-TERM TRACK FORECAST CONFIDENCE IS ONLY
MEDIUM, WITH THE OFFICIAL FORECAST PLACED NEAR THE CENTER OF THE
MULTI-MODEL GUIDANCE ENVELOPE. THIS CONSENSUS REPRESENTS A BLEND OF
DIVERGENT DYNAMICAL SOLUTIONS, INCLUDING THE FASTEST GFS, THE
MID-RANGE ECMWF ENSEMBLE MEAN AND NAVGEM, BRACKETED BY THE SLOWEST
UKMET, GALWEM, AND DETERMINISTIC ECMWF TRACKERS. WHILE THE GENERAL
STEERING PATTERN IS AGREED UPON, SIGNIFICANT UNCERTAINTY REMAINS
CONCERNING THE RATE OF ACCELERATION FOLLOWING THE INITIAL
QUASI-STATIONARY PHASE, AS WELL AS PROXIMITY OF THE TRACK TO THE
OWEN STANLEY RANGE. AN ADDITIONAL SOURCE OF FORECAST UNCERTAINTY
ARISES FROM POTENTIAL LAND INTERACTION, WHICH COULD INDUCE TRACK
DEFLECTIONS AND ACCELERATED WEAKENING SHOULD THE CYCLONE TRACK
CLOSER TO PAPUA NEW GUINEA. REGARDING INTENSITY, THE OBSERVED
STRUCTURAL CONSOLIDATION IS CORROBORATED BY NEARLY ALL GLOBAL
DYNAMICAL GUIDANCE. HOWEVER, OFFICIAL INTENSITY FORECAST CONFIDENCE
IS LOW DUE TO THE POTENTIAL NEGATIVE INFLUENCE OF THE UPWELLING
PHENOMENON AND THE LARGE ALONG-TRACK AND CROSS-TRACK SPREAD AMONG
MODELS. ADDITIONALLY, THE MESOSCALE MODELS (HAFS AND HWRF) PREDICT
AN IMMEDIATE WEAKENING DOWN TO 60 KTS BY TAU 24, AS A RESULT OF THE
UPWELLING EFFECTS.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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