WDPS31 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05P (FIVE) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.8S 176.2E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 132 NM WEST-SOUTHWEST OF SUVA, FIJI
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WITH DRY AIR CLEARING
OUT THE CONVECTIVE BLOWOFF ENOUGH TO REVEAL THE LOW LEVEL INFLOW
STRUCTURE ON THE WEST SIDE OF THE CIRCULATION. DEEP CONVECTION IS
FLARING TO THE EAST OF THE ASSESSED LLCC POSITION, JUST SOUTHWEST
OF VITI LEVU. A 090445Z SSMIS 89GHZ MICROWAVE IMAGE SHOWED THE
ASYMMETRIC NATURE OF THE SYSTEM TO GOOD EFFECT, WITH A SMALL BALL
OF CONVECTION EAST OF THE LLCC, WITH A BAND OF WEAKER CONVECTION
EXTENDING EQUATORWARD ALONG THE EASTERN PERIPHERY. THE INITIAL
POSITION IS ASSESSED WITH LOW CONFIDENCE IN LIGHT OF THE OBSCURED
NATURE OF THE LLCC AND THE LACK OF A DISTINCT CENTER FEATURE IN THE
MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 30 KNOTS IS ASSESSED
WITH MEDIUM CONFIDENCE, BASED ON AVAILABLE AGENCY CURRENT INTENSITY
ESTIMATES OF T2.0 FROM BOTH PGTW AND KNES, WHILE SLIGHTLY BELOW THE
PHFO ESTIMATE OF T2.5 AND THE OBJECTIVE AUTOMATED FIXES. AS
MENTIONED ABOVE, A SIGNIFICANT PLUG OF MID-LEVEL DRY AIR PUSHING IN
FROM THE WEST IS HINDERING CONSOLIDATION AND DEVELOPMENT OF A
STRONG CONVECTIVE CORE.

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

CURRENT STEERING MECHANISM: SOUTHWEST PERIPHERY OF A
NEAR-EQUATORIAL RIDGE (NER) TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   PHFO: T2.5 - 35 KTS
   CIMSS SATCON: 38 KTS AT 090206Z
   CIMSS ADT: 35 KTS AT 090540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT OVER WESTERN PERIPHERY. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   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: TROPICAL CYCLONE 05P IS FORECAST TO CONTINUE
TRACKING SOUTHEASTWARD OVER THE NEXT 12 HOURS ALONG THE
SOUTHWESTERN PERIPHERY OF A DEEP NER CENTERED TO THE NORTHEAST,
WHICH HAS OVER THE PAST SIX HOURS COME TO DOMINATE THE STEERING
FLOW. BY TAU 24, THE NER WEAKENS, ALLOWING FOR A BUILDING
SUBTROPICAL RIDGE (STR) TO THE SOUTH TO ASSUME THE DOMINATE
STEERING ROLE, ALLOWING TC 05P TO TURN SHARPLY WESTWARD THROUGH
ABOUT TAU 48. SHORTLY AFTER TAU 48, A STRONG MID-LATITUDE MAJOR
SHORTWAVE TROUGH WILL MOVE QUICKLY TO THE SOUTH, BREAKING THE STR.
IN RESPONSE, TC 05P WILL TURN SHARPLY SOUTH-SOUTHEASTWARD,
ACCELERATING INTO THE BREAK IN THE STR. THE TROUGH IS EXPECTED TO
RAPIDLY PASS TO THE SOUTH, WITH A NEW STR BUILDING IN OVER NEW
ZEALAND BY TAU 120, WHICH WILL SLOW THE FORWARD SPEED OF TC 05P.
THE UPPER-LEVEL ENVIRONMENT IS EXTREMELY COMPLEX, WITH THE SYSTEM
CURRENTLY RESIDING AT THE EQUATORWARD POINT OF AN UPPER-LEVEL
TROUGH, WHICH IS PROVIDING SOME RELATIVELY GOOD POLEWARD AND
EASTWARD OUTFLOW. HOWEVER THE PRESENCE OF THE DRY AIR DISCUSSED
EARLIER WILL HINDER THE RATE OF INTENSIFICATION IN THE NEAR TERM.
THE ENVIRONMENT MOISTENS AFTER TAU 24, WHICH COMBINED WITH THE
RELATIVELY GOOD OUTFLOW, WILL ALLOW FOR FASTER INTENSIFICATION TO A
PEAK OF 50 KNOTS BY TAU 36. AN UPPER-LEVEL LOW IS EXPECTED TO
CUTOFF FROM THE TROUGH WITH THE NEXT 12 HOURS, AND THE LLCC WILL
MOVE UNDER THIS UPPER LOW CENTER BY TAU 36, WHICH WILL INHIBIT
FURTHER INTENSIFICATION THEREAFTER. THE SYSTEM WILL AGAIN ENCOUNTER
SIGNIFICANT DRY AIR ENTRAINMENT, INCREASING NORTHWESTERLY VWS AND
DECREASING SSTS BY TAU 96, MARKING THE BEGINNING OF SUBTROPICAL
TRANSITION, WHICH WILL COMPLETE NO LATER THAN TAU 120.  

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE, WHILE
IN AGREEMENT ON THE OVERALL SCENARIO, SHOW A LARGE DEGREE OF SPREAD
THROUGH THE FORECAST PERIOD. THE JTWC TRACK LIES WITHIN THE
GROUPING OF THE BULK OF THE GUIDANCE MEMBERS, WITH NAVGEM AND GFS
REPRESENTING THE TWO OUTLIERS ON THE EAST AND WEST RESPECTIVELY.
THE ENSEMBLE MEMBERS ARE FOR THE MOST PART CONCENTRATED ON THE
WESTERN SIDE OF THE ENVELOPE AFTER TAU 48 AND THE JTWC TRACK IS
HEDGED IN THIS DIRECTION. HOWEVER, IN LIGHT OF THE COMPLEX AND
HIGHLY DYNAMIC STEERING PATTERN, THERE IS OVERALL LOW CONFIDENCE IN
THE JTWC FORECAST. INTENSITY GUIDANCE INDICATES FAIRLY QUICK
INTENSIFICATION TO 50 KNOTS WITH THE NEXT 24 HOURS, WHICH SEEMS A
BIT TOO FAST DUE TO THE PRESENCE OF THE DRY AIR AND THE CONTINUED
DIFFICULTY IN CORE CONSOLIDATION. THEREAFTER THE BULK OF THE
GUIDANCE SUGGESTS A STEADY OR SLIGHT INTENSIFICATION THROUGH THE
REMAINDER OF THE FORECAST. THE JTWC FORECAST PEAKS AT 50 KNOTS IN
LINE WITH THE BULK OF THE GUIDANCE BUT THE RATE OF INTENSIFICATION
IS LOWER. AFTER TAU 48, THE JTWC FORECAST IS SIGNIFICANTLY LOWER
THAN ALL AVAILABLE GUIDANCE. OVERALL CONFIDENCE IN THE INTENSITY
FORECAST IS MEDIUM TO LOW.  

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