WDXS32 PGTW 210300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (NINE) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.4S 104.4E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 440 NM EAST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED SATELLITE IMAGERY SHOWS TROPICAL CYCLONE 09S (NINE)
DEEPENED DURING ITS DIURNAL MAXIMUM PERIOD.  DVORAK ASSESSMENTS
FROM BOTH ABOM AND JTWC ROSE DURING THE PERIOD AND THE INTENSITY
ASSESSMENT IS RAISED TO 45KTS BASED ON THE JTWC DVORAK AND A PACK
OF CIMSS OBJECTIVE ASSESSMENTS, WITH SATCON THE HIGHEST AT 48KTS
AND THE LOWEST BEING THE MICROWAVE BASED DMINT AT 36KTS. THE SYSTEM
IS FIXED BETWEEN TWO LARGE GLOBES OF DEEP CONVECTION WITH
OVERSHOOTING TOPS THAT ARE SHOWING EARLY SIGNS OF CONSOLIDATING AND
ROTATING AROUND EACH OTHER.  WE SHALL SEE, HOWEVER, AS THE SYSTEM
HAS BEEN CYCLING OVER THE PAST THREE DAYS, PEAKING NEAR THE 00Z HOUR
ONLY TO WANE AGAIN AS THE SUN RISES OVER THE EASTERN INDIAN OCEAN.
A MOSAIC OF SCATTEROMETRY PASSES BETWEEN 14Z AND 15Z SHOW TROPICAL
CYCLONE NINE AS A RELATIVELY SMALL BUT WELL-ORGANIZED AND SYMMETRIC
SYSTEM. TC 09S IS SUPPORTED BY CONSTRUCTIVE INTERFERENCE BETWEEN A
NEGATIVE PHASE OF THE SOUTHERN INDIAN OCEAN DIPOLE, THE WEAKLY
NEGATIVE ENSO CYCLE, AND THE CONVECTIVE PHASE OF THE MADDEN JULIAN
OSCILLATION (MJO), WHICH HAS BEEN MAKING AN EXCELLENT ENVIRONMENT
FOR TROPICAL CYCLONE DEVELOPMENT AND INTENSIFICATION OVER THE COCOS
ISLAND REGION OVER THE PAST FORTNIGHT. BUT ALAS, THE IOD HAS
PEAKED AND IS BECOMING LESS NEGATIVE AND THE CONVECTIVE PHASE OF
THE MJO IS SHIFTING INTO THE MARITIME CONTINENT, SO THE PEAK PERIOD
OF IDEAL CONDITIONS HAS PASSED AND THE ENVIRONMENT IS BECOMING LESS
FAVORABLE.  ANIMATED WATER VAPOR IMAGERY SHOWS ROBUST EQUATORWARD
OUTFLOW OVER THE NORTHEAST QUADRANT AND EXCELLENT OUTFLOW OVER THE
SOUTHWEST QUADRANT.  DRIER AIR EXISTS UPSTREAM OF THE CURRENT
POSITION. EASTERLY VERTICAL WIND SHEAR MAXES OUT IN THE MID-LEVELS
AT 15-20KTS BUT IN THE OVERALL COLUMN IT AVERAGES ONLY 10KTS, AND
THE SYSTEM IS TRACKING IN ALMOST THE SAME DIRECTION AS THE SHEAR.
THE PRIMARY FORCES WORKING AGAINST IT ARE UPWELLING AND DRY AIR,
BOTH OF WHICH ARE WELL UPSTREAM OF THE CURRENT POSITION. THE
SOUTHERN INDIAN OCEAN MONSOON TROUGH IS DIS-JOINTED, WITH A BREAK
OCCURRING NEAR 95E AND THE TROUGH OVER THE CENTRAL INDIAN OCEAN SET UP
FURTHER EQUATORWARD, ALSO HINTING THAT THE STORM IS MOVING INTO A
MORE HOSTILE ENVIRONMENT.

INITIAL WIND RADII BASIS: PERSISTENCE FROM EARLIER ASCAT PASSES AT
201431Z AND 201511Z. 

CURRENT STEERING MECHANISM: THE EXTREME NORTHWESTERN FLANK OF THE
SUBTROPICAL RIDGE, WHICH IS ANCHORED IN AN ANTICYCLONE 15S 110E. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   APRF: T2.5 - 35 KTS
   CIMSS SATCON: 48 KTS AT 202233Z
   CIMSS ADT: 57 KTS AT 202030Z
   CIMSS D-MINT: 45 KTS AT 202232Z
   CIMSS D-PRINT: 45 KTS AT 202300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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: TROPICAL CYCLONE NINE WILL CHUG SLOWLY ALONG A
WESTWARD BEARING IN THE SOUTHERN HEMISPHERE MONSOON TROUGH AND
INTENSIFY STEADILY, TOPPING OUT AT LOW TYPHOON STRENGTH. THE SLOW
MOVEMENT OF THE SYSTEM WILL INDUCE UPWELLING, WITH COUPLED MODELS
SHOWING THE EFFECTS BEGINNING TO WEAR ON THE SYSTEM BEGINNING NEAR
TAU 48. 700-300MB MOISTURE PROGS SHOW DRIER AIR WRAPPING AROUND TO
THE EQUATORWARD SIDE OF THE SYSTEM BY TAU 72, BUT THE SAME MODELS
SHOW THE CORE STILL MANAGING TO COCOON ITSELF AND FIGHT OFF THE
WORST OF THE EFFECTS THROUGH THE END OF THE FORECAST. SO ALTHOUGH THE
SYSTEM SHOULD BEGIN A DOWNTREND IN INTENSITY NEAR TAU 72, ALL
GUIDANCE INDICATES THE SYSTEM WILL SURVIVE BEYOND THE END OF THE
FORECAST PERIOD AND BRING GALE FORCE WINDS TO THE COCOS ISLANDS FOR
CHRISTMAS. 


MODEL DISCUSSION: TRACK GUIDANCE IS TIGHT IN BEARING BUT THERE IS A
CONSIDERABLE ALONG-TRACK SPREAD THOUGH TAU 72. THE JTWC TRACK
FORECAST LEANS TOWARDS THE ECMWF ENSEMBLE. BEYOND TAU 72,
CROSS-TRACK AND ALONG TRACK SPREAD BECOME SO WIDE THAT CLIMATOLOGY, 
HISTORICAL TRACKS, AND VOODOO ARE THE PREFERRED BASELINES. INTENSITY
GUIDANCE IS CONSISTENT IN SHOWING A SLOPE OF INTENSIFICATION INTO
THE 48 TO 72 HOUR PERIOD, THEN A STEADY DOWNSLOPE THEREAFTER. THE
JTWC FORECAST STAYS CLOSE TO THE INTENSITY MEAN, WHICH IS JUST
BELOW THE CLIMATOLOGICAL MEAN OF ONE T-NUMBER A DAY. THE HIGHEST
GUIDANCE IS THE HAFS-A, WHICH GOES UP TO 90KTS AT TAU 72, BUT THE
HAFS-A TRACK BREAKS OFF FROM THE PACK AND MEANDERS AFTER TAU 48. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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