WDPS32 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09P (NINE) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.6S 155.7E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 735 NM WEST OF PORT VILA, VANUATU
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A WEAK,
POORLY-DISORGANIZED LOW-LEVEL CIRCULATION (LLC) WITH FLARING DEEP
CONVECTION OVER THE NORTHWEST PERIPHERY. A 021240Z GMI 89GHZ COLOR
COMPOSITE IMAGE ALSO INDICATES A WEAKLY-DEFINED LLC WITH ISOLATED
DEEP CONVECTION DISPLACED NORTHWEST. A FORTUITOUS 020851Z
SCATTEROMETER IMAGE REVEALS A DEFINED CIRCULATION WITH 10-15 KNOT
WINDS OVER THE SOUTHER N SEMICIRCLE AND A SWATH OF 25 KNOT WINDS
OVER THE NORTHERN SEMICIRCLE. DUE TO THE LACK OF ASCAT IMAGERY AND
HIGH-RESOLUTION MICROWAVE IMAGERY, THERE IS LOW CONFIDENCE IN THE
INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS
BASED ON THE KNES DVORAK ESTIMATE AND THE SCATTEROMETER DATA. TC
09P IS LOCATED UNDER AN UPPER-LEVEL COL REGION WITH COMPLEX FLOW;
DEEP CONVECTION IS FLARING UNDER THE DIVERGENT REGION OF THE COL
WHILE THE LLC IS LOCATED UNDER THE CONVERGENT REGION. POLEWARD
OUTFLOW IS RESTRICTED DUE TO THE PRESENCE OF AN UPPER-LEVEL LOW AND
TROUGH TO THE SOUTH AND SOUTHEAST. ADDITIONALLY, THERE IS 
SIGNIFICANT DRY AIR PRESENT OVER THE SOUTHERN PERIPHERY OF THE 
SYSTEM WITH MID-LEVEL DRY AIR ENTRAINMENT. SEA SURFACE TEMPERATURES 
(28-29C) AND VERTICAL WIND SHEAR REMAIN CONDUCIVE.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) POSITIONED
TO THE NORTH AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   KNES: T1.0 - 25 KTS
   CIMSS SATCON: 38 KTS AT 021109Z
   CIMSS ADT: 30 KTS AT 021140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC 09P IS FORECAST TO TRACK EASTWARD TO
EAST-SOUTHEASTWARD UNDER THE STEERING INFLUENCE OF THE NER THROUGH
TAU 72. TC 09P WILL MAINTAIN INTENSITY AT 25 KNOTS THROUGH TAU 24
DUE TO DRY AIR ENTRAINMENT AS WELL AS WEAK OUTFLOW ALOFT. AFTER TAU
24, THE SYSTEM WILL INTENSIFY SLOWLY AS POLEWARD OUTFLOW IMPROVES
AND THE CORE ENVIRONMENT MOISTENS. AFTER TAU 72, TC 09P WILL
GRADUALLY TURN SOUTHEASTWARD ALONG THE WESTERN FLANK OF A BUILDING
SUBTROPICAL RIDGE (STR) TO THE EAST. THE SYSTEM WILL PEAK AT 55
KNOTS BY TAU 96 THEN WEAKEN SLIGHTLY, HOWEVER, THIS PORTION OF THE
INTENSITY FORECAST IS UNCERTAIN DUE TO POSSIBLE DRY AIR ENTRAINMENT
AND SLIGHTLY COOLER SEA SURFACE TEMPERATURES (27-28C).  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH A
210NM SPREAD IN SOLUTIONS AT TAU 72 AND REMAIN IN FAIR AGREEMENT
THROUGH TAU 120. THE 020600Z ECMWF ENSEMBLE (EPS) STRIKE
PROBABILITY GRAPHIC SUPPORTS THE JTWC FORECAST TRACK WITH MEDIUM
CONFIDENCE. THE BULK OF THE DETERMINISTIC AND ENSEMBLE GUIDANCE
TURNS THE SYSTEM SOUTHEASTWARD BETWEEN NEW CALEDONIA AND VANUATU.
RELIABLE INTENSITY GUIDANCE SUPPORTS THE JTWC INTENSITY FORECAST
WITH HWRF INDICATING A PEAK OF ABOUT 55 KTS NEAR TAU 96 AND THE
JTWC INTENSITY CONSENSUS (ICNW) SHOWING A PEAK OF 60 KTS NEAR TAU
96. 

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