WDPS32 PGTW 312100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09P (NINE) WARNING NR 
001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0S 152.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 403 NM EAST-NORTHEAST OF CAIRNS, AUSTRALIA
   MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT, ASYMMETRICAL CIRCULATION WITH FLARING DEEP CONVECTIVE
ACTIVITY STRUGGLING TO MAINTAIN OVER THE ASSESSED LOW LEVEL
CIRCULATION CENTER (LLCC). A 311801Z SSMIS 37GHZ MICROWAVE IMAGE
DEPICTED AN AREA OF LOW EMISSIVITY WITH SHALLOW CONVECTIVE BANDING,
DISPLACED TO THE SOUTHEAST OF THE DEEPEST CONVECTION. AT FIRST
GLANCE, THIS DATA SUGGESTS THAT THE LLCC IS DISPLACED DOWN TRACK
FROM THE CONVECTIVE CORE. HOWEVER, IMAGE ARTIFACTS BRING THE WHOLE
PASS INTO QUESTION, AND A SOUTHEAST DISPLACEMENT OF THE LLCC DOES
NOT ALIGN WITH THE PGTW UPPER-LEVEL WIND ANALYSIS, NOR THE AGENCY
FIX POSITIONS. HENCE THE INITIAL POSITION IS ASSESSED WITH LOW
CONFIDENCE, HEDGED A BIT DOWN TRACK FROM THE AGENCY FIXES, TOWARDS
THE MICROWAVE INDICATED CENTER. THE INITIAL INTENSITY IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE TRIFECTA OF AGENCY FIXES, ALL AT
T2.5 (35 KNOTS) AND AN EARLIER 311156Z ASCAT-B PASS SHOWED A PATCH
OF 35 KNOT WINDS ALONG THE NORTHERN PERIPHERY OF THE CIRCULATION
CENTER. THE ENVIRONMENT IS MARGINAL, WITH MODERATE DIVERGENT
NORTHWESTERLY FLOW PROVIDING GOOD OUTFLOW INTO THE BASE OF AN
UPPER-LEVEL TROUGH TO THE SOUTH. SHEAR IS IN THE LOW TO MODERATE
RANGE. HOWEVER, THE SYSTEM LIES ALONG A TIGHT MOISTURE GRADIENT,
WITH LOW MOISTURE TO THE SOUTH AND HIGH MOISTURE ON THE NORTH SIDE,
WHICH IS INHIBITING CONSOLIDATION OF THE CONVECTIVE CORE.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   ABRF: T2.5 - 35 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TC 09S IS FORECAST TO TRACK GENERALLY
EAST-SOUTHEASTWARD THROUGH THE FIRST 36 HOURS ALONG THE SOUTHWEST
SIDE OF THE NER. AROUND TAU 48, THE STEERING ENVIRONMENT BECOMES
INCREASINGLY COMPLEX, WITH AN UPPER-LEVEL TROUGH MOVING EAST OVER
NEW CALEDONIA EXPECTED TO DEVELOP INTO A CUT-OFF LOW JUST SOUTH OF
NEW CALEDONIA, WITH A TROUGH EXTENDING EQUATORWARD. THE IMPACT OF
THIS LOW OR TROUGH ON TC 09P WILL IN GREAT EXTENT DEPEND UPON THE
ULTIMATE STRENGTH OF THE TROUGH AND HOW MUCH IT ERODES THE NER TO
THE NORTHEAST. AT THIS TIME, TC 09P IS FORECAST TO GRADUALLY TURN
SOUTHEASTWARD AFTER TAU 48, ALONG THE GRADIENT BETWEEN THE DEEP
TROUGH TO THE SOUTH AND THE NER TO THE NORTH. OVER THE NEXT 24-48
HOURS, UPPER-LEVEL OUTFLOW IS FORECAST TO DECREASE SLIGHTLY AS THE
TOUGH CURRENTLY TO THE SOUTH OF THE SYSTEM MOVES OFF TO THE EAST.
COMBINED WITH THE IMPACT OF THE SIGNIFICANT MID-LEVEL DRY AIR, WILL
CONTINUE TO INHIBIT SIGNIFICANT DEVELOPMENT THROUGH THE FIRST 48
HOURS OF THE FORECAST. BY TAU 72 HOWEVER, THE SYSTEM WILL MOVE INTO
AN AREA OF INCREASED MOISTURE, DECREASED VWS AND INCREASED OUTFLOW
ALOFT, ALLOWING FOR SLOW BUT STEADY INTENSIFICATION TO A PEAK OF 55 
KNOTS BY TAU 120. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN POOR
AGREEMENT, WITH A DRAMATIC INCREASE IN CROSS-TRACK SPREAD STARTING
AS EARLY AS TAU 24. THE GFS AND HWRF ARE THE EQUATORWARD OUTLIERS,
TAKING THE SYSTEM OVER NORTHERN OR CENTRAL VANUATU AND KEEPING THE
SYSTEM NORTH OF THE 22ND LATITUDE THROUGH THE FORECAST PERIOD. THE
UKMET AND THE EGRR REPRESENT THE POLEWARD OUTLIERS AND TURN THE
SYSTEM SHARPLY INTO THE TROUGH AFTER TAU 72, REPRESENTING A 470NM
SPREAD AT TAU 120. THE REMAINDER OF THE GUIDANCE PACKAGE LIES
ACROSS A 180NM ENVELOPE HEDGED TO THE NORTH OF THE MULTI-MODEL
CONSENSUS MEAN. ENSEMBLE GUIDANCE IS SHOWS A SIMILAR AMOUNT OF
UNCERTAINTY, WITH THE ECMWF ENSEMBLE IN A FAIRLY TIGHT CLUSTER IN
LINE WITH THE DETERMINISTIC CONSENSUS WHILE THE GFS ENSEMBLE SHOWS
GREATER SPREAD IN POTENTIAL SOLUTIONS, PARTICULARLY AFTER TAU 72.
THE JTWC FORECAST LIES ON THE NORTH EDGE OF THE INSIDE ENVELOPE IN
THE DETERMINISTIC GUIDANCE AND CLOSE TO THE ECMWF ENSEMBLE MEAN.
CONFIDENCE IS MEDIUM THROUGH TAU 72, BUT DECREASES TO LOW
THEREAFTER DUE TO THE HIGH DEGREE OF UNCERTAINTY IN THE GUIDANCE.
INTENSITY GUIDANCE ALSO SHOWS A HIGH DEGREE OF UNCERTAINTY, WITH
THE DECAY SHIPS INDICATING STEADY INTENSIFICATION THROUGH THE
FORECAST TO A PEAK OF 75 KNOTS WHILE THE HWRF SHOWS NEAR-TERM
WEAKENING FOLLOWED BY SLOW INTENSIFICATION TO A PEAK OF 60 KNOTS.
THE JTWC FORECAST CLOSELY TRACKS THE HWRF SOLUTION THROUGH THE
FORECAST PERIOD, THOUGH CONFIDENCE IS LOW AND THE SMALL SIZE OF THE
SYSTEM MEANS THAT SMALL-SCALE CHANGES TO THE OVERALL ENVIRONMENT
WILL HAVE OUTSIZED EFFECTS ON THE INTENSITY.  

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