WDXS32 PGTW 190300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (NINE) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.5S 108.9E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 659 NM NORTH-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE 09S WITH PERSISTENT DEEP CONVECTION DISPLACED TO THE 
WEST OF THE LOW-LEVEL CIRCULATION CENTER (LLCC). THE VORTEX CONTINUES 
TO HAVE SIGNIFICANT WESTWARD TILT WITH HEIGHT DUE TO THE MODERATE 
EASTERLY SHEAR. AN 182312Z GMI 89 GHZ MICROWAVE IMAGE REVEALED 
DEFINED LOW-LEVEL CLOUD LINES WRAPPING INTO THE EXPOSED LLCC, 
SUPPORTING THE INITIAL POSITION WITH HIGH CONFIDENCE. THE INITIAL 
INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY 
DVORAK FIXES AND CIMSS OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. 
ENVIRONMENTAL ANALYSIS INDICATES THAT 09S IS IN A MARGINALLY 
FAVORABLE ENVIRONMENT CHARACTERIZED BY WEAK OUTFLOW ALOFT, 
MODERATE (15-20 KTS) EASTERLY VERTICAL WIND SHEAR, DRY AIR TO THE 
EAST, AND WARM (28-29 C) SEA SURFACE TEMPERATURES.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: NORTHERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) POSITIONED TO THE SOUTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   APRF: T2.5 - 35 KTS
   CIMSS ADT: 33 KTS AT 190000Z
   CIMSS AIDT: 29 KTS AT 190000Z
   CIMSS DPRINT: 32 KTS AT 190000Z
   CIMSS DMINT: 35 KTS AT 182316Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK RADIAL
   OTHER FACTORS: DRY AIR OVER THE EASTERN PERIPHERY 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 09S IS FORECAST TO CONTINUE TRACKING GENERALLY 
WESTWARD ALONG THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE TO 
THE SOUTH THROUGHOUT THE FORECAST PERIOD. NEAR TAU 36, THE 
SUBTROPICAL RIDGE IS EXPECTED TO BREAK, HOWEVER, STEERING INFLUENCE 
IS EXPECTED TO REMAIN WESTWARD AS RIDGING QUICKLY BUILDS BACK IN TO
THE SOUTHWEST. REGARDING INTENSITY, 09S IS FORECAST TO MAINTAIN ITS 
CURRENT INTENSITY THROUGH TAU 24 UNDER THE EFFECTS OF THE MARGINALLY 
FAVORABLE ENVIRONMENT. THERE IS A DISTINCT POSSIBILITY FOR THE SYSTEM 
TO SLIGHTLY WEAKEN THROUGH THIS TIME IF THE CONVECTION BECOMES 
SEPARATED TOO FAR FROM THE CENTER. AROUND TAU 24, THE EASTERLY SHEAR 
IS EXPECTED TO WEAKEN WHICH WILL ALLOW THE VORTEX TO BECOME MORE 
VERTICALLY ALIGNED. AS A RESULT, 09S IS FORECAST TO STEADILY 
INTENSIFY THROUGH TAU 96 TO AROUND 70 KTS. 

MODEL DISCUSSION: ONGOING COMMUNICATIONS OUTAGES AT JTWC CONTINUE TO
CAUSE THERE TO BE VERY LIMITED MODEL GUIDANCE FOR THE SYSTEM. OF NOTE,
THE GFS AND ITS ENSEMBLE MEAN TRACKS THE SYSTEM FURTHER POLEWARD THAN 
THE GOOGLE DEEPMIND AND ECMWF ENSEMBLE MEANS. THE JTWC TRACK FORECAST 
IS PLACED CLOSER TO THE LATTER MODEL GROUPING WITH LOW CONFIDENCE. 
INTENSITY GUIDANCE IS IN POOR AGREEMENT WITH HAFS-A QUICKLY 
INTENSIFYING THE SYSTEM AFTER TAU 48 UP TO OVER 100 KTS AT TAU 96.  
HWRF IS MUCH LESS AGGRESSIVE, PEAKING THE SYSTEM AT AROUND 65 KTS. 
THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE HAFS-A THROUGH 
TAU 48 AND THEN CLOSER TO HWRF THROUGH TAU 120 WITH LOW CONFIDENCE.

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