WDPS31 PGTW 090300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 30P (MAILA) WARNING NR 
015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 8.5S 155.1E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 741 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 30P (MAILA) WITH A SLIGHTLY RAGGED 15NM EYE AND PRESSURE
ALONG THE SOUTHEASTERN QUADRANT. THE CULPRIT FOR THE DEFORMATION
WITHIN THE SOUTHEASTERN QUADRANT IS ATTRIBUTED TO THE MODERATE
EASTERLY SHEAR ACTING ON THE SYSTEM. A PARTIAL 082305Z METOP-B
ASCAT PASS CAUGHT THE CENTER OF THE CIRCULATION, LENDING HIGH
CONFIDENCE TO THE INITIAL POSITION AND WESTERN WIND RADII. THE
INITIAL INTENSITY OF 100 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON PERSISTENCE FROM A 081917Z SEN-1 SAR IMAGE SHOWING A VMAX
PEAK OF 103 KTS. AGENCY DVORAK AND CIMSS OBJECTIVE ESTIMATES ARE
ANALYZED TO BE CURRENTLY OVERESTIMATING THE SURFACE WIND FIELD WHEN
COMPARED TO THE SAR OUTPUT. ENVIRONMENTAL ANALYSIS INDICATES THAT
30P IS CURRENTLY IN A MARGINALLY FAVORABLE ENVIRONMENT
CHARACTERIZED BY MODERATE EQUATORWARD OUTFLOW ALOFT, MODERATE
EASTERLY VERTICAL WIND SHEAR, AND WARM SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: 082305Z METOP-B ASCAT SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED OVER NORTHERN AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   ABRF: T6.0 - 115 KTS
   CIMSS ADT: 115 KTS AT 090000Z
   CIMSS AIDT: 110 KTS AT 090000Z
   CIMSS D-PRINT: 105 KTS AT 090000Z

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

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: TRACK SPEEDS HAVE BEEN SLOWED DOWN
COMPARED TO THE PREVIOUS FORECAST TO ACCOUNT FOR THE POSSIBILITY OF
FURTHER SLOW MOVEMENT WITHIN THE SOLOMON SEA OVER THE NEXT 3-4 DAYS

FORECAST DISCUSSION: TC 30P IS FORECAST TO TRACK GENERALLY
WESTWARD, ALONG THE NORTHWESTERN PERIPHERY OF THE STR OVER CENTRAL
AUSTRALIA THROUGH TAU 24. NEAR TAU 24, RIDGING IS EXPECTED TO BUILD
TO THE SOUTHEAST OF THE SYSTEM, DRIVING IT SOUTHWESTWARD THROUGH
TAU 120. A TRACK NEAR THE TIP OF THE PAPUAN PENINSULA IS FORECAST
TO OCCUR NEAR TAU 96. HOWEVER, THERE HAS STARTED TO BE SIGNIFICANT
UNCERTAINTY REVOLVING AROUND THE POTENTIAL FOR FURTHER SLOW
MOVEMENT AND DISSIPATION WITHIN THE SOLOMON SEA. THE SYSTEM IS
CURRENTLY FORECAST TO STEADILY WEAKEN THROUGH TAU 48 DUE TO A TRACK
THROUGH THE POOL OF COLD WATERS THAT WAS LEFT IN THE WAKE OF 30P.
THE TRACK BACK THROUGH THE COLD POOL, ALONG WITH THE PERSISTENT
EASTERLY VERTICAL WIND SHEAR, WILL CAUSE 30P TO WEAKEN. AS
IT STANDS, THE JTWC FORECAST CALLS FOR WEAKENING THROUGHOUT THE
ENTIRE FORECAST PERIOD AND A SLOWER MOVEMENT AFTER TAU 24 AS IT
ATTEMPTS TO TRACK OFF TO THE WEST-SOUTHWEST. THERE IS A POSSIBILITY 
THAT THE SYSTEM DISSIPATES EAST OF PAPUA NEW GUINEA IF A
SLOWER TRACK MOVEMENT OCCURS OVER THE NEXT 72 HOURS.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS NOW IN VERY
POOR AGREEMENT WITH THE ECMWF DETERMINISTIC, ECMWF ENSEMBLE MEAN,
AND THE GOOGLE DEEPMIND ENSEMBLE MEAN ALL NOW SHOWING A TRACK THAT
NEVER ESCAPES THE SOLOMON SEA. THIS HAS NOW CAUSED THERE TO BE
EXTREMELY LOW CONFIDENCE IN THE JTWC TRACK FORECAST. THE JTWC TRACK
IS PLACED NEAR THE CONSENSUS THROUGH TAU 48 AND THEN CLOSER TO THE
GFS ENSEMBLE MEAN THROUGH TAU 120. INTENSITY GUIDANCE HAS ONE
REMAINING OUTLIER IN THE COAMPS-TC, WHICH IS NOW THE ONLY MODEL
THAT SUGGESTS FURTHER INTENSIFICATION. OTHER THAN COAMPS-TC, THE
REMAINDER OF GUIDANCE SUGGESTS STEADY WEAKENING THROUGHOUT THE
ENTIRE FORECAST PERIOD. THE JTWC INTENSITY FORECAST IS PLACED NEAR
THE MULTI-MODEL CONSENSUS WITH LOW CONFIDENCE DUE TO THE POSSIBILITY 
OF AN EARLIER DISSIPATION TIMELINE. 

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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