WDPS31 PGTW 080300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.0S 155.9E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 757 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 30P WITH A CLOUD-FILLED EYE IN AN ASYMMETRICAL CANOPY.
DRY AIR AND EASTERLY VERTICAL WIND SHEAR ARE EATING AWAY AT THE
STORM'S EASTERN FLANK, LEADING TO LACK OF DEEP CONVECTION AND A
HIGHLY COMPRESSED CENTRAL DENSE OVERCAST ON THE EASTERN SEMICIRCLE.
ENVIRONMENTAL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT
CHARACTERIZED BY LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM
(29-30 KTS) SEA SURFACE TEMPERATURES, AND MODERATE OUTFLOW ALOFT,
OFFSET BY POTENTIAL COLD WATER UPWELLING THE STORM HAS INDUCED
WHILE QUASISTATIONARY. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE CLOUD-FILLED EYE ON ANIMATE MSI. THE
INITIAL INTENSITY OF 115 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AUTOMATED CIMSS INTENSITY ESTIMATES AND THE AGENCY
SUBJECTIVE DVORAK FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

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


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   ABRF: T6.5 - 127 KTS
   CIMSS ADT: 122 KTS AT 080040Z
   CIMSS AIDT: 114 KTS AT 080040Z
   CIMSS D-PRINT: 102 KTS AT 080040Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 30P (MAILA) IS EXPECTED TO SLOWLY TRACK
WEST-NORTHWESTWARD FROM THE NEXT 24 HOURS WHILE IT REMAINS IN THE
RELATIVELY WEAK STEERING ENVIRONMENT OF THE NORTHEASTERN PERIPHERY
OF THE STR CENTERED OVER AUSTRALIA. AROUND TAU 36, THE STR IS
EXPECTED TO BUILD A EASTWARD EXTENSION THAT WILL CAUSE 30P TO
INCREASE TRANSLATION SPEED AND ACCELERATE SOUTHWESTWARD TOWARD CAPE
YORK FOR THE REMAINDER OF THE FORECAST PERIOD. REGARDING INTENSITY,
30P IS FORECAST TO CONTINUE A GRADUAL WEAKENING TREND FOR THE
DURATION OF THE FORECAST PERIOD, INITIALLY INDUCED BY UPWELLING IN
THE SOLOMON SEA CAUSED BY MAILA'S QUASISTATIONARY TRACK THROUGH TAU
36, THE MID-LEVEL SHEAR WILL TAKE OVER AS THE PRIMARY WEAKENING
MECHANISM FROM TAU 48 UNTIL TAU 120. TOWARDS THE END OF THE
FORECAST PERIOD (TAU 96-120), 30P WILL BEGIN TO ENTRAIN DRY AIR
INTO ITS CORE, FURTHER HASTENING WEAKENING. THE QUESTION OF WHAT
IMPACT A POTENTIAL COLD POOL WOULD HAVE ON MAILA REMAINS A CENTRAL
UNCERTAINTY SURROUNDING THE INTENSITY FORECAST; HOWEVER AT THIS
TIME, ALL INDICATORS ARE SUGGESTING COLD WATER UPWELLING WILL HAVE
A SIZEABLE IMPACT ON THE STORM'S INTENSITY WHILE IT REMAINS IN THE
SOLOMON SEA.

MODEL DISCUSSION: DETERMINISTIC TRACK MODEL GUIDANCE IS IN POOR
AGREEMENT ON OVERALL TRACK, WITH PHYSICS-BASED DETERMINISTIC MODELS
STEADILY TRACKING 30P SOUTHWESTWARD WHILE THE EXPERIMENTAL AI-BASED
MODELS DEPICT 30P REMAINING QUASISTATIONARY FOR SIGNIFICANTLY
LONGER. THIS DISCREPANCY INDUCES LARGE ALONG-TRACK SPREAD BY TAU
120. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED WITH OVERALL LOW 
CONFIDENCE. RELIABLE INTENSITY GUIDANCE ARE IN STRONG AGREEMENT THAT 
30P WILL STEADILY WEAKEN UNTIL THE END OF THE FORECAST PERIOD. 
NOTABLY, THE MESOSCALE MODELS (HAFS-A AND HWRF) DEPICT A MUCH MORE 
DRASTIC WEAKENING TREND THROUGH TAU 24. THE JTWC INTENSITY FORECAST IS
ASSESSED WITH OVERALL LOW CONFIDENCE, AS A RESULT OF THE
UNCERTAINTIES REGARDING POTENTIAL INTERACTION WITH
THE COLD POOL AND THE MAGNITUDE OF THE MID-LEVEL SHEAR THE STORM
WILL ENCOUNTER AS IT TRANSITS SOUTHWESTWARD.

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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