WDXS31 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (TWENTYNINE) 
WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.5S 122.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 265 NM NORTH OF BROOME, AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 29S WITH SLIGHTLY ELONGATED LOW-LEVEL CIRCULATION
CENTER (LLCC), PARTIALLY OBSCURED BY THE DEEP CONVECTION. THE
INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE
EXTRAPOLATION FROM A 132230Z F16 SSMIS MICROWAVE IMAGERY SUITE, IN
CONJUNCTION WITH THE VISIBLE IMAGERY LOOP. THE INITIAL INTENSITY OF
40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A PERSISTENT
CONVECTIVE STRUCTURE, AS WELL AS THE AGENCY DVORAK AND OBJECTIVE
INTENSITY ESTIMATES LISTED BELOW. ENVIRONMENTAL CONDITIONS REMAIN
FAVORABLE FOR DEVELOPMENT, WITH WARM (29-30 C) SEA SURFACE
TEMPERATURES (SST), ABUNDANT MOISTURE THROUGHOUT THE COLUMN,
MODERATE POLEWARD AND EQUATORWARD OUTFLOW AND LOW VERTICAL WIND
SHEAR (5-10 KTS).

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED OVER
WESTERN AUSTRALIA

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 48 KTS AT 132330Z
   CIMSS ADT: 49 KTS AT 132330Z
   CIMSS AIDT: 37 KTS AT 132330Z
   CIMSS D-MINT: 26 KTS AT 132230Z
   CIMSS D-PRINT: 29 KTS AT 132330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: MULTIPLE RAPID INTENSIFICATION (RI)
WERE TRIGGERED DURING THE MOST RECENT RUN

FORECAST DISCUSSION: TC 29S IS EXPECTED TO MOVE WEST-SOUTHWESTWARD
OVER THE NEXT 12-24 HOURS BEFORE TURNING WEST, INFLUENCED BY THE
SUBTROPICAL RIDGE (STR) TO THE SOUTH. AROUND TAU 48, A PASSING LONG
WAVE TROUGH IS FORECAST TO DISRUPT THE RIDGE, ALTERING THE STEERING
ENVIRONMENT. THIS WILL CAUSE THE SYSTEM TO SLOW DOWN AND BEGIN A
TURN TOWARD THE AUSTRALIAN COASTLINE BY TAU 96. CONDITIONS ARE
EXPECTED TO IMPROVE FURTHER, WITH MID-LEVEL SHEAR DECREASING,
ALLOWING FOR RAPID INTENSIFICATION, AS SUGGESTED BY MULTIPLE RI
AIDS (DTOP, RICN AND FRIA) AND SUPPORTED BY THE COMPACT NATURE OF
THE SYSTEM. TC 29S IS PROJECTED TO PEAK AT 100-105 KTS BETWEEN TAUS
48 AND 72. AFTER THIS POINT, AS A LONG WAVE TROUGH PASSING TO THE
SOUTH BEGINS INTERACTING WITH THE SYSTEM, RAPID WEAKENING IS
EXPECTED DUE TO INCREASING WESTERLY SHEAR AND A DRIER ENVIRONMENT.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT THROUGH
THE INITIAL 48 HOURS, AS WITNESSED BY IMPROVED CROSS-TRACK SPREAD
OF 55 NM AND AN ALONG-TRACK SPREAD OF 90 NM. BEYOND TAU 48 HOWEVER,
MODEL DIVERGENCE INCREASES SIGNIFICANTLY, WITH CROSS-TRACK SPREAD
EXCEEDING 350 NM BY TAU 120. FORECAST UNCERTAINTY REMAINS HIGH
THROUGHOUT THE REMAINDER OF THE FORECAST. UKMET AND GALWEM CONTINUE
TO PREDICT THE SYSTEM TRACKING NORTH OF THE CONSENSUS AND EXECUTING
A SHARP EASTWARD U-TURN, WHILE OTHERS FAVOR A GRADUAL SOUTHWARD
TURN AROUND TAU 72, FOLLOWED BY MOVEMENT TOWARD THE AUSTRALIAN
COAST. GIVEN THE LARGE MODEL SPREAD AND UNCERTAINTY IN THE TIMING
OF THE TROUGH PASSAGE, THE LONG-TERM TRACK FORECAST HAS LOW
CONFIDENCE, WHILE THE SHORT-TERM FORECAST IS ASSESSED WITH MEDIUM
CONFIDENCE. THE JTWC FORECAST TRACK GENERALLY FOLLOWS THE
MULTI-MODEL CONSENSUS, LEANING TOWARD THE MAJORITY OF THE
SOLUTIONS. IN TERMS OF INTENSITY, MOST MODELS CONTINUE TO AGREE ON
RAPID OR NEAR-RAPID INTENSIFICATION THROUGH TAU 60, FOLLOWED BY
RAPID WEAKENING. THE MOST CONSERVATIVE MODELS ARE STILL
DETERMINISTIC GFS AND STATISTICAL-DYNAMICAL MODELS, WHICH SUGGEST
PEAK INTENSITY OF 70-85 KTS, WHILE HAFS REMAINS THE MOST
AGGRESSIVE, FURTHER INCREASING THE PREDICTED MAXIMUM WINDS TO
150-155 KTS, OCCURRING BETWEEN TAUS 48 AND 60. AS A RESULT OF THE
HUGE GUIDANCE SPREAD, THE JTWC INTENSITY FORECAST HAS MEDIUM
CONFIDENCE THROUGH THE FIRST 72 HOURS, AND LOW CONFIDENCE
THEREAFTER, AND IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS.


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