WDPS31 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (JASPER) WARNING NR 
031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.5S 147.3E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 121 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE
SYSTEM HAS A WEAKENED CONVECTIVE STRUCTURE WITH DECREASED WRAP AND
BANDING OVER THE LAST SIX HOURS. THE RAGGED LOW LEVEL CIRCULATION
HAS ALSO BECOME PARTIALLY EXPOSED. CONVECTIVE TOPS ALONG THE SOUTH
AND SOUTH-SOUTHWESTERN PORTIONS OF THE LOW-LEVEL CIRCULATION HAS
CONTINUED TO WARM, WHILE OVERALL OUTFLOW HAS REMAINED MINIMAL. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON DEFINED
LOW-LEVEL CYCLONIC CIRCULATION OBSERVED ON THE WILLIS ISLAND RADAR
LOOP BETWEEN 1130-1200Z. THE INITIAL INTENSITY IS PLACED WITH
MEDIUM CONFIDENCE AND HELD ALONG AUTOMATED DVORAK ESTIMATES TO
REFLECT DECREASING CONVECTIVE STRUCTURES AROUND LOW-LEVEL
CIRCULATION AND TILTED VERTICAL STRUCTURE TO THE EAST. ANALYSIS
INDICATED THE ENVIRONMENT IS MARGINAL WITH LOW VWS AND WARM SST
OFFSET BY CONTINUED MINIMAL OUTFLOW AND COOL DRY AIR INTRUSION.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: MID-LEVEL SUB-TROPICAL RIDGING TO THE
SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T2.5 - 35 KTS
   ABRF: T3.0 - 45 KTS
   CIMSS SATCON: 42 KTS AT 120930Z
   CIMSS ADT: 33 KTS AT 121130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK POLEWARD

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 JASPER WILL PROGRESS MORE WESTWARD UNDER
THE STEERING STR TO THE SOUTH AND MAKE LANDFALL IN THE VICINITY OF
PORT DOUGLAS, APPROXIMATELY 74NM NORTH-NORTHWEST OF CAIRNS AROUND
TAU 18. THE MARGINAL ENVIRONMENT WILL MAINTAIN ITS CURRENT
INTENSITY AT BEST UP TO TAU 12. AFTERWARD, LAND INTERACTION AND
CONTINUED DRY AIR INTRUSION WILL INCREASE AND RAPIDLY WEAKEN JASPER
TO DISSIPATION BY TAU 48 AS IT PROGRESSES FURTHER INLAND. THE
REMNANTS OF TC JASPER IS EXPECTED TO CONTINUE WESTWARD AND EXIT
INTO THE GULF OF CARPENTARIA BY TAU 72.   

MODEL DISCUSSION: NUMERICAL MODELS ARE IN CLOSE AGREEMENT WITH THE
MAIN PACK GRADUALLY AND EVENLY SPREADING TO 109NM BY TAU 48. THE
JTWC TRACK FORECAST IS LAID WITH HIGH CONFIDENCE ON TOP OF THE
CONSENSUS.   

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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