WDXS32 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (NINE) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.8S 101.2E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 254 NM EAST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 09S HAS TRACKED SOUTHWEST OVER THE PAST SIX
HOURS AS THE STEERING INFLUENCE HAS TRANSFERRED TO THE SUBTROPICAL
RIDGE FEATURE TO THE SOUTHWEST. THE GENERAL CIRCULATION HAS
CONTINUED TO WEAKEN, WITH PERSISTENT CONVECTION RELEGATED TO THE
SOUTHERN SEMICIRCLE AND ASSOCIATED WARMING CLOUD TOP TEMPERATURES
ILLUSTRATED ON ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY.
ENVIRONMENTAL ANALYSIS PORTRAYS A MARGINALLY FAVORABLE ENVIRONMENT
FOR CONTINUED DEVELOPMENT WITH SEA SURFACE TEMPERATURES RANGING
FROM 27 C TO 28 C, LOW VERTICAL WIND SHEAR (05-10 KTS), AND
MODERATE POLEWARD OUTFLOW. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON EIR IMAGERY AND A 221222Z 37 GHZ SSMIS MI. THE
INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON A CONSENSUS BETWEEN OBJECTIVE AND SUBJECTIVE ESTIMATES
CHARACTERIZING A WEAKENING TREND.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTHWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   DEMS: T2.5 - 35 KTS
   APRF: T2.0 - 30 KTS
   CIMSS SATCON: 48 KTS AT 220900Z
   CIMSS ADT: 45 KTS AT 221300Z
   CIMSS AIDT: 36 KTS AT 221300Z
   CIMSS D-MINT: 33 KTS AT 221224Z
   CIMSS D-PRINT: 35 KTS AT 221300Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TC 09S WILL CONTINUE TO TRACK PRIMARILY
WESTWARD WITH A SLIGHT NORTH AND SOUTH OSCILLATION COINCIDING WITH
THE STRENGTH OF THE PRIMARY STEERING MECHANISM, THE SUBTROPICAL
RIDGE TO THE SOUTHWEST. SOME INTENSIFICATION IS FORECASTED WITH A
PEAK INTENSITY OF 60 KTS EXPECTED NEAR TAU 72 AS THE FORECASTED
ENVIRONMENT REMAINS MARGINALLY FAVORABLE FOR CONTINUED DEVELOPMENT.
SOME UNCERTAINTY IN THE EXPECTED INTENSIFICATION EXISTS AS 09S
ALREADY DISPLAYS MODERATE SIGNS OF WEAKENING. IN ADDITION,
INTENSIFICATION IS HEAVILY DEPENDENT ON THE SUBTROPICAL RIDGE
REMAINING RELATIVELY STRONG AND KEEPING TC 09S FROM TRACKING
FURTHER SOUTHWARD. REGARDLESS OF THE TRACK, TC 09S IS FORECASTED TO
SLOWLY FILL AND WEAKEN AFTER TAU 72 DUE TO PROLONGED EXPOSURE TO A
DRIER ENVIRONMENT.

MODEL DISCUSSION: CROSS TRACK SPREAD AMONG NUMERICAL MODEL GUIDANCE
HAS INCREASED TO 90 NM AT TAU 48 WITH CONTINUED SPREADING
THEREAFTER. THE MAJORITY OF THE GUIDANCE KEEPS THE FORECASTED TRACK
PRIMARILY WESTWARD WITH GFS AND NAVGEM PERSISTENT IN THE NOW
SOUTHWEST DIRECTION OF THE CIRCULATION. THE ALONG TRACK SPREAD HAS
IMPROVED SLIGHTLY WITH THE EUROPEAN MODEL GUIDANCE SLOWING DOWN THE
SYSTEM QUICKER. THE JTWC FORECASTED TRACK REMAINS CLOSE TO THE
MULTI MODEL CONSENSUS WHICH KEEPS THE TRACK CLOSE TO THE COCOS
ISLANDS. INTENSITY GUIDANCE IS IN BETTER AGREEMENT WITH ONLY HAFS-A
AND COAMPS-TC DEPICTING INTENSITIES ABOVE 60 KTS. A MAJORITY OF THE
MODEL GUIDANCE AGREE ON A SLOW WEAKENING TREND FOLLOWING TAU 72.
THE JTWC INTENSITY FORECAST REFLECTS CLOSELY TO THE MULTI MODEL
CONSENSUS.  

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