WDPS31 PGTW 052100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03P (JASPER) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 9.8S 157.5E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 149 NM WEST OF HONIARA, SOLOMON ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
CONSOLIDATING TROPICAL STORM STRENGTH CIRCULATION WITH IMPROVED
BANDING FEATURES IN ALL QUADRANTS. A 051704Z SSMIS 91GHZ MICROWAVE
IMAGE INDICATES IMPROVED DEEP CONVECTIVE BANDING THAT IS WRAPPED
AROUND THE NORTHERN SEMICIRCLE WHILE LOW LEVEL CLOUD LINES ARE
VISIBLE TO THE SOUTH OF THE LLCC. THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON PARTIALLY OBSCURED NATURE OF THE
LLCC IN EIR AND SSMIS IMAGERY. THE INITIAL INTENSITY OF 55 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY DVORAK INTENSITY
ESTIMATES AS WELL AS CIMSS AUTOMATED ESTIMATES INDICATING 45-60KTS
WITH THE MAJORITY FALLING CLOSER TO 55KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE (NER) TO THE
EAST-SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   ABRF: T3.0 - 45 KTS
   CIMSS SATCON: 46 KTS AT 051442Z
   CIMSS ADT: 43 KTS AT 051710Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 03P (JASPER) IS STILL LOITERING, NEARLY
QUASI-STATIONARY (QS) DUE WEST OF THE SOLOMON ISLANDS. OVER THE
NEXT SIX HOURS, THE NER TO THE EAST OF THE SYSTEM IS FORECASTED TO
BUILD WESTWARD AND PUSH 03P GENERALLY SOUTH-SOUTHWESTWARD. AS THE
SYSTEM PICKS UP SPEED, FAVORABLE ENVIRONMENTAL CONDITIONS,
CHARACTERIZED BY VIGOROUS OUTFLOW ALOFT, WARM SSTS AND LOW VERTICAL
WIND SHEAR (VWS) WILL RAPIDLY INTENSITY THE SYSTEM TO OVER 100KTS
BY TAU 48. AFTER TAU 48, INCREASING VWS, DECREASED OUTFLOW ALOFT
AND THE ONSET OF WESTERLY COOL DRY AIR INTO THE PERIPHERY OF THE
SYSTEM WILL GRADUALLY WEAKEN 03P. BY TAU 72, 03P WILL TRANSITION
STEERING CONTROL TO A SUBTROPICAL RIDGE (STR) DUE SOUTH OF THE
CIRCULATION. AS VWS AND OUTFLOW WORSEN, THE SYSTEM WILL FALL TO
ROUGHLY 70KTS BY TAU 96 AND AROUND 60KTS BY TAU 120 AS THE STR TO
THE SOUTH FORCES THE SYSTEM TOWARDS THE EASTERN COAST OF AUSTRALIA.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT, SHOWING A
113NM SPREAD IN SOLUTIONS BY TAU 72. DESPITE THE SOLID CROSS TRACK
AGREEMENT, ALONG TRACK SPREADING DOES INCREASE WITH TIME. FOR THIS
REASON THE JTWC FORECAST TRACK IS PLACED WITH OVERALL MEDIUM
CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS ALSO IN GOOD
AGREEMENT, WITH ALL MEMBERS INCLUDING SEVERAL RAPID INTENSIFICATION
(RI) AIDS, INDICATING A SHARP INCREASE TO JUST OVER 100KTS BY TAU
48 AND A GRADUAL DECLINE THERE AFTER. FOR THIS REASON THE JTWC
INTENSITY FORECAST IS ALSO PLACED WITH OVERALL MEDIUM CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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