WDPS31 PGTW 060300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.5S 154.7E
   INITIAL INTENSITY: 90 KTS
   GEOGRAPHIC REFERENCE: 683 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: EASTWARD AT 01 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 30P (MAILA) HAS TRACKED VERY SLOWLY ON AN
EASTWARD CRAWL OVER THE PAST 6 HOURS AS IT CONTINUES TO MAKE A
COUNTERCLOCKWISE LOOP. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
(MSI) DEPICTS TC 30P WITH A COMPACT INNER-CORE OF DEEP CONVECTION
AND A CLOUD-FILLED EYE FEATURE. AN APPARENT INCREASE IN
EAST-SOUTHEASTERLY VERTICAL WIND SHEAR HAS CAUSED THE LOW-LEVEL
CLOUD LINES WITHIN THE SOUTHEASTERN PERIPHERY TO BECOME EXPOSED. A
051929Z RCM-2 SAR IMAGE REVEALED A SYMMETRICAL CORE OF 85-90 KNOT
WINDS WITHIN ALL QUADRANTS. THE INITIAL INTENSITY OF 90 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SAR DATA, AGENCY
DVORAK FIXES OF T4.5-5.0, AND RECENT DPRINT ESTIMATES HOVERING
AROUND 80-90 KTS. ADT AND AIDT HAVE CONSISTENTLY BEEN TOO LOW,
LIKELY DUE TO THE COMPACT SIZE OF THE CORE OF THE SYSTEM. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON TRACKING
THE EYE FEATURE IN ANIMATED MSI. ENVIRONMENTAL ANALYSIS INDICATES
THAT 30P REMAINS IN A FAVORABLE ENVIRONMENT WITH STRONG POLEWARD
OUTFLOW ALOFT, LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR, AND
WARM (28-29 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: PERSISTENCE FROM 051929Z RCM-2 SAR DATA

CURRENT STEERING MECHANISM: A COMPETING STEERING ENVIRONMENT WITH
A NEAR-EQUATORIAL RIDGE (NER) POSITIONED TO THE NORTH AND A
SUBTROPICAL RIDGE (STR) OVER NORTHERN AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T4.5 - 77 KTS
   ABRF: T4.5 - 77 KTS
   CIMSS ADT: 61 KTS AT 060020Z
   CIMSS AIDT: 52 KTS AT 060020Z
   CIMSS D-PRINT: 85 KTS AT 060020Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

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 FORECAST TO REMAIN WITHIN A
COMPETING STEERING ENVIRONMENT, SANDWICHED BETWEEN RIDGING TO BOTH
THE NORTH AND SOUTH, THROUGH TAU 48. DURING THIS TIME, THE SYSTEM
IS EXPECTED TO CONTINUE MOVING AT A VERY SLOW PACE WITH POTENTIALLY
ERRATIC DIRECTIONALITY. AS IT STANDS, A COMPLETION OF THE
COUNTERCLOCKWISE LOOP IS FORECAST THROUGH TAU 48. AFTER TAU 48, THE
RIDGING TO THE NORTH WILL MOVE NORTHWARD, AND THE RIDGING OVER
AUSTRALIA WILL BECOME THE PRIMARY STEERING MECHANISM. THIS WILL
ALLOW FOR 30P TO ACCELERATE WEST-SOUTHWESTWARD THROUGH TAU 120.
THERE REMAINS A CONSIDERABLE AMOUNT OF UNCERTAINTY REGARDING HOW
QUICKLY THE SYSTEM WILL MOVE OUT TO THE WEST AND AT WHAT LATITUDE.
THE JTWC TRACK FORECAST CALLS FOR 30P SKIRTING THE TIP OF THE
PAPUAN PENINSULA BETWEEN TAUS 96 AND 120, THOUGH THAT IS SUBJECT TO
CHANGE. IN TERMS OF INTENSITY, 30P IS FORECAST TO CONTINUE
INTENSIFYING OVER THE NEXT 12 HOURS AS THE ENVIRONMENT REMAINS
FAVORABLE WITH LOW SHEAR, WARM SST, AND STRONG POLEWARD OUTFLOW.
AFTER TAU 12, THE UPWELLING OF COOLER WATERS WILL BEGIN TO IMPACT
THE SYSTEM DUE TO THE SLOW MOVEMENT WITHIN THE SOLOMON SEA. THIS
WILL CAUSE THE INTENSIFICATION TREND TO HALT. BY TAU 36, THE COLD
POOL WILL BEGIN TO DETERIORATE THE VORTEX AND WEAKEN THE SYSTEM
THROUGH TAU 72. BY TAU 96, ONCE THE SYSTEM HAS STARTED TO DISTANCE
ITSELF FROM THE COLD POOL, 30P WILL ATTEMPT TO RECOVER AND
REINTENSIFY. HOWEVER, IF THE SYSTEM CLIPS THE PAPUAN PENINSULA, THE
BRIEF TERRAIN INTERACTION WILL HINDER REDEVELOPMENT. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE GENERALLY AGREES
ON A TRACK EASTWARD THROUGH TAU 36 FOLLOWED BY A SLOW TURN TO THE
WEST THROUGH TAU 72. AFTER TAU 72, MODELS DIVERGE WILL VARYING
TRACK SPEEDS. THERE REMAINS TWO MAIN GROUPING OF MODELS WITH AI
MODELS AND PHYSICS-BASED MODELS. THE PHYSICS BASED MODELS DEPICT
MUCH QUICKER TRACK SPEEDS WHILE THE AI MODELS ARE SLUGGISH IN THE
WESTWARD MOVEMENT. BY TAU 120, THE GOOGLE DEEPMIND ENSEMBLE MEAN IS
JUST EAT OF THE PAPUAN PENINSULA WHILE GFS IS NEARING THE CAPE YORK
PENINSULA. THE JTWC TRACK FORECAST IS PLACED NEAR THE CONSENSUS
THROUGH TAU 72 AND THEN HEDGED BETWEEN THE GOOGLE DEEPMIND AND ECMF
ENSEMBLE MEANS THROUGH TAU 120 WITH LOW CONFIDENCE. INTENSITY
GUIDANCE IS SPLIT WITH HAFS-A AND HWRF BOTH SUGGESTING GRADUAL
WEAKENING FROM TAU 0 ONWARD. ON THE OTHER HAND, THERE ARE A HANDFUL
OF RAPID INTENSIFICATION AIDS THAT CONTINUE TO TRIGGER THROUGH TAU
24. AFTER TAU 24, MODELS AGREE ON STEADY WEAKENING THROUGH TAU 120.
THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY CLOSE TO THE RI
MODELS THROUGH TAU 24 AND THEN NEAR THE MULTI-MODEL CONSENSUS
THROUGH THE REMAINDER OF THE FORECAST PERIOD WITH LOW CONFIDENCE
DUE TO THE UNCERTAINTIES REGARDING THE TRACK. 

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