WDPS31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (JASPER) WARNING NR 
030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9S 147.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 100 NM NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS
MOSTLY MAINTAINED CONVECTIVE STRUCTURE WITH SLIGHTLY IMPROVED WRAP
AND BANDING OVER THE LAST SIX HOURS. CONVECTIVE TOPS ALONG THE
SOUTHERN QUADRANT HAVE WARMED AND OUTFLOW HAS REMAINED MINIMAL. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A
PARTIAL LOW LEVEL FEATURE IN THE 120417Z AMSR2 89GHZ IMAGE. THE
INITIAL INTENSITY IS ALSO PLACED WITH MEDIUM CONFIDENCE AND HELD
SLIGHTLY HIGHER THAN AGENCY AND AUTOMATED DVORAK ESTIMATES TO
REFLECT THE SLIGHT IMPROVEMENT IN WRAP AND BANDING. ANALYSIS
INDICATES THE ENVIRONMENT IS MARGINALLY FAVORABLE WITH LOW VWS AND
WARM SST OFFSET BY MINIMAL OUTFLOW AND COOL DRY AIR INTRUSION.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.0 - 45 KTS
   ABRF: T3.0 - 45 KTS
   CIMSS SATCON: 43 KTS AT 120417Z
   CIMSS ADT: 43 KTS AT 120530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TC JASPER WILL TRACK MORE WESTWARD UNDER THE
STEERING STR TO THE SOUTH AND MAKE LANDFALL OVER CAPE YORK
APPROXIMATELY 63NM NORTH-NORTHWEST OF CAIRNS AROUND TAU 18. THE
MARGINALLY FAVORABLE ENVIRONMENT WILL MAINTAIN ITS CURRENT
INTENSITY AT BEST UP TO TAU 12. AFTERWARD LAND INTERACTION AND DRY
AIR INTRUSION WILL GRADUALLY THEN RAPIDLY WEAKEN IT TO DISSIPATION
BY TAU 48 AS IT TRACKS ACROSS FURTHER INLAND. THE REMNANTS OF TC
JASPER IS EXPECTED TO EXIT INTO THE GULF OF CARPENTARIA BY TAU 72. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH THE
MAIN PACK GRADUALLY AND EVENLY SPREADING TO A MERE 62NM BY TAU 48.
NAVGEM IS THE SOLE LEFT OF TRACK OUTLIER. THE JTWC TRACK FORECAST
IS LAID WITH HIGH CONFIDENCE JUST TO THE RIGHT OF CONSENSUS TO
OFFSET NAVGEM. 

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