WDXS32 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 09S (NINE) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.3S 105.3E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 493 NM EAST OF THE COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: WESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TROPICAL CYCLONE (TC) 09S HAS BECOME MORE COMPACT OVER THE PAST SIX
HOURS WITH A TIGHTLY WRAPPED LOW-LEVEL CIRCULATION CENTER (LLCC)
THAT HAS CONTINUED TO PRODUCE DEEP CONVECTION AS SEEN VIA ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY. CLOUD TOP TEMPERATURES
HAVE COOLED TO NEGATIVE 90 DEGREES CELSIUS. ENVIRONMENTAL
CONDITIONS REMAIN MARGINALLY FAVORABLE FOR DEVELOPMENT WITH WARM
SEA SURFACE TEMPERATURES (27 C TO 28 C) AND LOW VERTICAL WIND SHEAR
(5-10 KTS) BALANCED BY WEAK POLEWARD OUTFLOW. THE INITIAL POSITION
IS PLACED WITH MEDIUM CONFIDENCE BASED ON AGENCY FIXES. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
SUBJECTIVE AND OBJECTIVE ESTIMATES REMAINING STEADY OR DECREASING
SLIGHTLY OVER THE PAST TWELVE HOURS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUB-TROPICAL RIDGING TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   DEMS: T3.0 - 45 KTS
   APRF: T2.0 - 30 KTS
   CIMSS ADT: 59 KTS AT 201330Z
   CIMSS AIDT: 45 KTS AT 201330Z
   CIMSS D-MINT: 41 KTS AT 201154Z
   CIMSS D-PRINT: 49 KTS AT 201330Z

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

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 (TC) 09S WILL CONTINUE TO
TRACK WESTWARD UNDER THE INFLUENCE OF SUB-TROPICAL RIDGING TO THE
SOUTH. THE FORECASTED LOW VERTICAL WIND SHEAR WILL ALLOW THE SYSTEM
TO REACH A PEAK INTENSITY OF 65 KNOTS AROUND TAU 72. AFTERWARDS THE
CIRCULATION WILL STRUGGLE AGAINST A SLIGHT INCREASE IN VERTICAL
WIND SHEAR AND DRY AIR ENTRAINMENT WHICH WILL EVENTUALLY INDUCE A
SLOW WEAKENING TREND FOR THE REMAINDER OF THE FORECASTED PERIOD.
THERE IS LOW CONFIDENCE IN THE 72-120 HOUR FORECAST AS A LARGE
AMOUNT OF UNCERTAINTY REMAINS IN REGARDS TO THE ABILITY OF TC 09S
TO RETAIN SYMMETRICAL STRUCTURE AND COMPACT NATURE AMPLIFIED BY
COMPETING STEERING MECHANISMS AT THE END OF THE FORECAST PERIOD. 

MODEL DISCUSSION: MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE
CONTINUED WESTWARD TRACK OF 09S. TRACK SPEEDS REMAIN HIGHLY
VARIABLE ESPECIALLY AFTER TAU 72. THE JTWC TRACK FORECAST REMAINS
CLOSE TO THE MULTI MODEL CONSENSUS BETWEEN TAU 12 AND TAU 72 BUT IS
QUICKER THAN THE CONSENSUS FOR THE REMAINDER OF THE FORECAST
PERIOD, DRIVEN BY STRENGTHENING SUBTROPICAL RIDGE CENTERED TO THE
SOUTH-SOUTHWEST. INTENSITY GUIDANCE HAS COME INTO BETTER AGREEMENT
WITH A MAJORITY OF THE MODELS DEPICTING A STEADY RISE TO 65 KT
STRENGTH BEFORE A SLOW WEAKENING TREND AFTER TAU 72, HOWEVER
SIGNIFICANT ALONG-TRACK SPREAD WILL IMPACT THE TIMELINE OF
INTENSITY DEVELOPMENT. SOME GUIDANCE SUGGESTS THAT POTENTIAL FOR
RAPID INTENSIFICATION EXISTS, THOUGH THE INCREASING DRY AIR
ENTRAINMENT AND POOR OUTFLOW CONDITIONS MAKE THIS OUTCOME LESS
LIKELY. THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE MULTI
MODEL CONSENSUS WITH MEDIUM CONFIDENCE FOR THE FIRST 72 HOURS AND
LOW CONFIDENCE AFTERWARDS.

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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