WDPS31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.7S 155.3E
   INITIAL INTENSITY: 85 KTS
   GEOGRAPHIC REFERENCE: 703 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT
CENTRAL DENSE OVERCAST (CDO) FEATURE QUASI-STATIONARY IN THE
SOLOMON SEA. OVER THE PAST SIX HOURS, ANIMATED ENHANCED INFRARED
(EIR) IMAGERY SHOWS A TRANSIENT EYE ATTEMPTING TO DEVELOP, WITH
ANOTHER ATTEMPT ONGOING AT THE PRESENT TIME. HOWEVER, THERE IS
STILL A MODERATE AMOUNT OF VORTEX TILT DUE TO PERSISTENT MODERATE
EASTERLY SHEAR (CURRENTLY ESTIMATED AT 16 KNOTS BY CIMSS). WHILE
DEEP CONVECTIVE HOT TOWERS CONSISTENTLY FORM ON THE NORTHERN SIDE
OF THE NASCENT EYE (AS DEPICTED IN RECENT MICROWAVE IMAGERY), THEY
FAIL TO ROTATE UPSHEAR DUE TO THE MODERATE SHEAR, INHIBITING
INTENSIFICATION. THUS THE SYSTEM HAS BEEN RELATIVELY STAGNANT IN
TERMS OF INTENSITY FOR THE PAST 12 HOURS. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON EXTRAPOLATION OF EARLIER
MICROWAVE IMAGERY AND THE HIGH CONGRUENCE OF AGENCY FIX POSITIONS.
THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON
A BLEND OF THE AGENCY SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES,
SUPPORTED BY THE CIMSS D-PRINT AND SATCON. OF NOTE, THE ADT AND
AIDT HAVE BEEN CONSISTENTLY UNDERESTIMATING THE INTENSITY OF TC
30P. ENVIRONMENTAL CONDITIONS ARE FAVORABLE, WITH MODERATE EASTERLY
SHEAR, WARM SSTS AND GOOD EQUATORWARD OUTFLOW. A NOTABLE NEGATIVE
FACTOR IS THE UPWELLING OF COOLER WATERS, WITH THE LATEST OHC AND
SST ANALYSES SUGGESTING THE LEADING EDGE OF THE COOLER WATER MAY
ALREADY BE REACHING THE SURFACE.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN, WITH A
SUBTROPICAL RIDGE (STR) OVER NORTHERN AUSTRALIA AND STRONG
NORTHWESTERLY GRADIENT FLOW JUST SOUTH OF THE EQUATOR. CURRENTLY,
THE NORTHWESTERLY FLOW IS SLIGHTLY PREDOMINANT. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   KNES: T5.0 - 90 KTS
   ABRF: T4.5 - 77 KTS
   CIMSS SATCON: 83 KTS AT 060600Z
   CIMSS ADT: 57 KTS AT 060530Z
   CIMSS AIDT: 61 KTS AT 060530Z
   CIMSS D-MINT: 73 KTS AT 060320Z
   CIMSS D-PRINT: 87 KTS AT 060700Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: UPWELLING OF COOLER OCEANIC WATERS REDUCING OCEAN
HEAT CONTENT.  

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 30P (MAILA) IS FORECAST
TO CONTINUE MEANDERING AROUND THE SOLOMON SEA FOR THE NEXT 36-48
HOURS IN A WEAK AND COMPETING STEERING PATTERN. CURRENTLY, THE
NORTHWESTERLY GRADIENT FLOW TO THE NORTH APPEARS TO BE SLIGHTLY
AHEAD IN TERMS OF THE PRIMARY STEERING INFLUENCE, PUSHING TC 30P
SLOWLY EAST-SOUTHEASTWARD. THE GRADIENT IS ALREADY BEGINNING TO
WEAKEN HOWEVER, AND BY TAU 36 SHOULD BE WEAK ENOUGH TO ALLOW A
GRADUAL CHANGE IN THE TRAJECTORY TC 30P, WITH THE SYSTEM EXPECTED
TO SLOWLY LOOP NORTH THEN WESTWARD BY TAU 48. AFTER TAU 48, RIDGING
BUILDING TO THE EAST OF TC 30P WILL INITIATE A KICK-OUT TOWARDS
THE WEST, THEN AFTER TAU 72, THE STR OVER AUSTRALIA IS FORECAST TO
BUILD AND MOVE EASTWARD TO A POSITION SOUTH OF TC 30P. THIS WILL
RESULT IN AN ACCELERATING TRAJECTORY TOWARDS WEST-SOUTHWEST THROUGH
TAU 120. THE SYSTEM IS FORECAST TO CLIP THE FAR SOUTHEASTERN TIP OF
PAPUA NEW GUINEA, PASSING CLOSE TO THE EASTERN APPROACHES OF MILNE
BAY AROUND TAU 96, THEN MOVING INTO THE FAR NORTHERN REACHES OF THE
CORAL SEA BY THE END OF THE FORECAST PERIOD. REGARDING INTENSITY,
THE SYSTEM HAS ONLY A SHORT WINDOW OF OPPORTUNITY TO GAIN FURTHER
INTENSITY, BEFORE SIGNIFICANTLY COOLER WATERS REACH THE SURFACE AND
CHOKE OFF ITS ENERGY SOURCE. THE FORECAST CALLS FOR A PEAK OF 95
KNOTS AT TAU 12, THEN A LEVELING OFF PERIOD, FOLLOWED BY RAPID
WEAKENING THROUGH TAU 48 AS MODELS PREDICT SEA SURFACE TEMPERATURES
COULD DROP AS LOW AS 23C IN THE COLD UPWELLED REGION. AFTER THE
SYSTEM KICKS OUT TO THE WEST AND AWAY FROM THE COLD POOL, A PERIOD
OF REINTENSIFICATION IS FORECAST, WITH A SECOND PEAK OF AROUND 90
KNOTS EXPECTED AROUND TAU 72. HOW HIGH THIS SECOND PEAK REACHES
ULTIMATELY DEPENDS ON HOW MUCH THE SYSTEM WEAKENS WHILE LOITERING
OVER THE COLD POOL, WHICH POTENTIALLY COULD BE MUCH MORE THAN
CURRENTLY FORECASTED. AS THE SYSTEM MOVES OVER THE TIP OF PAPUA NEW
GUINEA, THE VORTEX IS LIKELY TO BE SHREDDED, ALONG WITH SIGNIFICANT
INFLOW DISRUPTION, LEADING TO A SUBSTANTIAL WEAKENING. WHILE THE
SYSTEM SHOULD RECOVER ONCE IN THE CORAL SEA, FORECASTED MODERATE
SHEAR WILL KEEP A LID ON REINTENSIFICATION, THOUGH THERE IS
CONSIDERABLE UNCERTAINTY IN THIS FINAL FORECAST POINT DUE TO
UNCERTAINTY IN THE EXACT TRACK BEYOND TAU 72. 

MODEL DISCUSSION: TRACK GUIDANCE IS STEADILY COMING INTO BETTER
AGREEMENT. AT THIS POINT, THE BULK OF THE CONSENSUS MEMBERS NOW
AGREE ON A SOUTHEASTWARD TRACK THROUGH TAU 24, A COUNTER-CLOCKWISE
LOOP BACK TO THE WEST BY TAU 48 AND THEN A KICK-OUT TO THE
SOUTHWEST BY TAU 72. THE AI CONSENSUS AND EC-AIFS ARE THE ONLY TWO
OUTLIERS SHOWING A TRACK FURTHER NORTHWARD BUT EVEN THEY SHOW A
GRADUAL WESTWARD LOOP THROUGH TAU 72. CROSS-TRACK ENVELOPE SPREAD
AT TAU 72 IS 63NM EXCLUDING THE TWO AI MODELS NOTED ABOVE. THE JTWC
FORECAST IS PLACED NEAR THE CONSENSUS MEAN THROUGH TAU 72 WITH
MEDIUM CONFIDENCE. BEYOND TAU 72, SAME RELATIONSHIPS APPLY, WITH
THE AI MODELS REMAINING FAR TO THE NORTH, WHILE THE REMAINDER OF
THE GUIDANCE PACKAGE DEPICTING A SOUTHWESTWARD TRAJECTORY.
CROSS-TRACK SPREAD BETWEEN THE GALWEM AND FNV3 ON THE NORTH AND THE
ECMWF ENSEMBLE MEAN ON THE SOUTH, INCREASES TO 135NM BY TAU 120.
ALONG-TRACK SPREAD IS MORE SIGNIFICANT, INCREASING TO 330N BETWEEN
THE ECMWF (FAST, APPROACHING THE QUEENSLAND COAST) AND TH EGRR
(SLOW, NEAR MILNE BAY) BY THE END OF THE FORECAST. THE JTWC
EXTENDED FORECAST IS POSITIONED JUST NORTH OF THE CONSENSUS MEAN,
WITH LOW CONFIDENCE. INTENSITY GUIDANCE IS MIXED THROUGH THE ENTIRE
PERIOD, HIGHLY DEPENDENT UPON THE EXACT TRACK POSITION AND THE
DIFFERENCES BETWEEN THE COUPLED AND NON-COUPLED MODELS. THE COUPLED
MODELS DEPICT A PEAK INTENSITY BETWEEN TAU 12 AND TAU 24 FOLLOWED
BY BETWEEN 20-30 KNOTS OF WEAKENING BEFORE MODEST REINTENSIFICATION
BEFORE WEAKENING AGAIN FROM TAU 72 TO TAU 120. THE HAFS-A BOTTOMS
OUT AROUND 60 KNOTS AND THE HWRF AROUND 75 KNOTS. THE JTWC FORECAST
MOST CLOSELY FOLLOWS THE ECMWF AND COAMPS-TC GUIDANCE, BUT
CONFIDENCE REMAINS LOW THROUGH THE FORECAST PERIOD. 

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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