WDXS32 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (NINE) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.2S 109.2E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 668 NM NORTH-NORTHWEST OF LEARMONTH,
AUSTRALIA
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
CYCLONE 09S WITH PERSISTENT DEEP CONVECTION SLIGHTLY OFFSET 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 181332Z METOP-B ASCAT PASS REVEALED AN ASYMMETRIC 
WIND FIELD WITH GALE-FORCE WINDS CONFINED TO THE WESTERN SEMICIRCLE 
OF THE SYSTEM. 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 FROM 181332Z METOP-B SCATTEROMETER DATA 

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 SATCON: 34 KTS AT 181600Z
   CIMSS ADT: 33 KTS AT 181800Z
   CIMSS AIDT: 32 KTS AT 181800Z
   CIMSS DPRINT: 38 KTS AT 181800Z

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: 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: 09S IS FORECAST TO CONTINUE TRACKING WESTWARD
ALONG THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE SOUTH
THROUGH 36. NEAR TAU 36, THE RIDGE IS EXPECTED TO BREAK, CAUSING 
TRACK SPEEDS TO SLOW AND THE TRACK TO DIP MORE WEST-SOUTHWESTWARD. 
THE SYSTEM IS THEN EXPECTED TO CONTINUE ON A WEST-SOUTHWESTWARD 
TRACK THROUGH THE REMAINDER OF THE FORECAST PERIOD UNDER THE 
INFLUENCE OF RIDGING TO THE SOUTHEAST AND SOUTHWEST. REGARDING 
INTENSITY, 09S IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY THROUGH
TAU 36 UNDER THE EFFECTS OF THE MARGINALLY FAVORABLE ENVIRONMENT. 
THERE IS A POSSIBILITY FOR THE SYSTEM TO SLIGHTLY WEAKEN THROUGH 
THIS TIME IF THE CONVECTION BECOMES SEPARATED TOO FAR FROM THE 
CENTER. AROUND TAU 36, THE EASTERLY SHEAR IS EXPECTED TO WEAKEN 
WHICH WILL ALLOW THE VORTEX TO BECOME BETTER ALIGNED. AS A RESULT,
09S IS FORECAST TO STEADILY INTENSIFY THROUGH TAU 96. 

MODEL DISCUSSION: ONGOING COMMUNICATIONS OUTAGES AT JTWC CONTINUE TO
CAUSE THERE TO BE VERY LIMITED MODEL GUIDANCE FOR THE SYSTEM. GFS 
AND NAVGEM BOTH TRACK THE SYSTEM MUCH FURTHER IN THE POLEWARD 
DIRECTION THAN THE GOOGLE DEEPMIND AND ECMWF ENSEMBLE MEANS. THE 
JTWC TRACK FORECAST IS PLACED CLOSER TO THE LATTER MODELS WITH LOW 
CONFIDENCE. INTENSITY GUIDANCE IS IN POOR AGREEMENT WITH HAFS-A 
QUICKLY INTENSIFYING THE SYSTEM AFTER TAU 48 UP TO 95 KTS AT TAU 96. 
HWRF IS MUCH LESS AGGRESSIVE, KEEPING THE INTENSITY RATHER STAGNANT 
THROUGHOUT THE FORECAST PERIOD. THE JTWC INTENSITY FORECAST IS PLACED
CLOSE TO THE HAFS-A THROUGH TAU 48 AND THEN WITH A WEAKER RATE OF 
INTENSIFICATION THROUGH TAU 96 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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