WDPS31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24P (TWENTYFOUR) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9S 150.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 286 NM EAST-NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY HAS DEPICTED
TROPICAL CYCLONE 24P BECOMING ELONGATED OVER THE PAST 6 HOURS. DEEP
CONVECTION HAS REMAINED DISPLACED FAR TO THE WEST OF THE LOW-LEVEL
CIRCULATION CENTER (LLCC). A 041117Z METOP-C ASCAT PASS REVEALED
THE STRETCHED WIND FIELD WITH TROUGHING EXTENDING SOUTHEASTWARD AND
WESTWARD FROM THE CENTER. THE INITIAL POSITION AND INTENSITY ARE
BOTH PLACED WITH HIGH CONFIDENCE BASED ON THE ASCAT PASS.
ENVIRONMENTAL ANALYSIS INDICATES A MARGINAL ENVIRONMENT DUE TO WEAK
POLEWARD OUTFLOW ALOFT, MODERATE (15-20 KTS) EASTERLY VERTICAL WIND
SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: 041117Z METOP-C ASCAT SCATTEROMETER DATA

CURRENT STEERING MECHANISM: A COMBINED INFLUENCE FROM A SUBTROPICAL
RIDGE (STR) POSITIONED OVER CENTRAL AUSTRALIA AND RIDGING TO THE
EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   ABRF: T2.0 - 30 KTS
   CIMSS ADT: 30 KTS AT 041200Z
   CIMSS AIDT: 34 KTS AT 041200Z
   CIMSS D-MINT: 31 KTS AT 040916Z
   CIMSS D-PRINT: 30 KTS AT 041200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 24P IS FORECAST TO TRACK SOUTHWESTWARD OVER
THE NEXT 48 HOURS UNDER THE COMBINED INFLUENCE OF THE SUBTROPICAL
RIDGE POSITIONED OVER CENTRAL AUSTRALIA AND RIDGING TO THE EAST.
24P IS FORECAST TO MAKE LANDFALL SOUTH OF CAIRNS AT AROUND 060600Z.
THE RIDGE TO THE EAST IS EXPECTED TO BUILD AND BECOME THE PRIMARY
STEERING MECHANISM AFTER THE SYSTEM MAKES LANDFALL, CAUSING THE
VORTEX TO TURN MORE POLEWARD THROUGH THE END OF THE FORECAST
PERIOD. 24P IS FORECAST TO MARGINALLY INTENSIFY TO AROUND 40 KTS AS
IT APPROACHES THE QUEENSLAND COAST. ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO REMAIN MARGINAL WITH WEAK OUTFLOW AND MODERATE EASTERLY
SHEAR HINDERING ANY SIGNIFICANT DEVELOPMENT. AFTER LANDFALL,
TERRAIN INTERACTION WILL QUICKLY ERODE THE SYSTEM WITH DISSIPATION
EXPECTED TO OCCUR NO LATER THAN TAU 72. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN MODERATE
AGREEMENT WITH THE EXCEPTION OF TWO OUTLIERS, GALWEM AND UKMET,
WHICH BOTH TRACK THE VORTEX SIGNIFICANTLY FURTHER NORTHWARD THAN
THE REMAINDER OF GUIDANCE. DISCOUNTING THE TWO OUTLIERS, THERE IS A
CROSS-TRACK SPREAD OF AROUND 90 NM AT TAU 48, WHICH OPENS UP TO 160
NM AT TAU 72. THE JTWC TRACK FORECAST IS PLACED NEAR THE GOOGLE
DEEPMIND AND ECMWF ENSEMBLE MEANS WITH MEDIUM CONFIDENCE. INTENSITY
GUIDANCE AGREES ON A GENERALLY STEADY INTENSITY THROUGH TAU 36
BEFORE WEAKENING. THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO
THE CONSENSUS WITH HIGH CONFIDENCE. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH//
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