WDPN32 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (NINE) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.4N 124.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 406 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS VASTLY
IMPROVED CONVECTIVE ORGANIZATION THAT IS FULLY OBSCURING THE LOW
LEVEL CIRCULATION CENTER (LLCC) BENEATH. A FORTUITOUS 240651Z SSMIS
89GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS A NEARLY COMPLETE
MICROWAVE EYE WITH A TIGHT, ROBUST CONVECTIVE BAND FIGHTING TO
OVERPOWER THE UP SHEAR SIDE OF THE CIRCULATION. SWITCHING BETWEEN
THE 37GHZ AND 89GHZ MICROWAVE IMAGES REVEALS LITTLE TO NO
DISPLACEMENT OF THE CIRCULATION CENTERS WITH HEIGHT, INDICATING
FAVORABLE CONDITIONS OF RI DUE TO REDUCED VERTICAL WIND SHEAR. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND
SSMIS IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON THE NEARLY COMPLETE MICROWAVE EYE IN
SSMIS IMAGERY AND DVORAK INTENSITY ESTIMATES BREAKING CONSTRAINTS
TO T3.0, WHILE MOST AUTOMATED INTENSITY ESTIMATES HAVE YET TO
REFLECT THE ONGOING RI AND ARE THEREFOR MUCH LOWER.

INITIAL WIND RADII BASIS: 240100Z SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 32 KTS AT 240530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
   OTHER FACTORS: LIKELY IMMINENT ONSET OF RAPID INTENSIFICATION
(RI)

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: TS 09W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD UNDER THE FADING INFLUENCE OF A STR TO THE EAST.
AFTER TAU 12, THIS EASTWARD STR COMPLETELY BREAKS DOWN AND IS
REPLACED BY A NEW STR TO THE WEST, CENTERED OVER THE SOUTH CHINA
SEA. AS THIS TRANSFER HAPPENS, THE SYSTEM WILL MAKE A SHARP
EQUATORWARD TURN AND MAINTAIN THAT COURSE UNTIL TAU 72. AFTER
PASSING EQUATORWARD OF 18N, A NEAR EQUATORIAL RIDGE (NER) BUILDS
DUE SOUTH OF THE SYSTEM, HALTING ALL FORWARD PROGRESS AND SHARPLY
TURNING THE SYSTEM POLEWARD. BY TAU 96 AND THROUGH TAU 120, THIS
NER FORCES 09W POLEWARD AND EVENTUALLY WESTWARD TOWARDS THE LUZON
STRAIT. IN TERMS OF INTENSITY, 09W IS LIKELY UNDERGOING RAPID
INTENSIFICATION (RI) AS WE SPEAK. AS SLIGHT NORTHERLY SHEAR WAS THE
ONLY LIMITING FACTOR, NEW SSMIS IMAGERY TOGETHER WITH CIMSS
ATMOSPHERIC MOTION VECTORS (AMVS), SUGGEST THIS IS NO LONGER THE
CASE. BY TAU 24, FUELED BY SOUP-LIKE SEA SURFACE TEMPERATURES, HIGH
OHC VALUES AND HIGHLY FAVORABLE ATMOSPHERIC CONDITIONS, 09W WILL
QUICKLY ACHIEVE TYPHOON STRENGTH AND CONTINUE TO INTENSITY TO AN
ESTIMATED 115KTS BY TAU 72. AS THE SYSTEM EXECUTES THE COMPLICATED
BARREL ROLE THAT WILL TRACK IT TOWARDS THE LUZON STRAIGHTS, THERE
IS A CHANCE FOR A DURATION OF NEAR QUASI-STATIONARY (QS) MOVEMENT
NEAR TAUS 80-96. A PERIOD OF QS MAY LIMIT FURTHER INTENSIFICATION
DUE TO UPWELLING OF COOLER WATERS, BUT THIS EFFECT WOULD QUICKLY BE
NEGATED ONCE POLEWARD MOTION IS ONCE AGAIN ACHIEVED. AS IT STANDS,
JTWC IS FORECASTING A PEAK INTENSITY NEAR 120KTS BY TAU 96, WHICH
IS MAINTAINED THROUGH TAU 120.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT
CONSIDERING THE COMPLICATED NATURE OF THE STEERING PATTERN
THROUGHOUT THE FORECAST. MEMBER GUIDANCE IS BEST THROUGH TAU 72,
WITH ALL MEMBERS TAKING THE SAME GENERAL TRACK THAT JTWC HAS
FORECAST. AFTER TAU 72 HOWEVER, MEMBER GUIDANCE QUICKLY DIVERGES AS
MODELS EXECUTE THEIR TURNS AT DIFFERENT TIMES AND IN SOME CASES
DIFFERENT DIRECTIONS TOWARDS THE LUZON STRAITS. FOR THESE REASON
THE JTWC TRACK FORECAST IS PLACED INITIALLY WITH MEDIUM CONFIDENCE
AND WITH LOW CONFIDENCE THEREAFTER. RELIABLE MODEL INTENSITY
GUIDANCE IS IN GOOD AGREEMENT WITH ALL MEMBER INDICATING RI THROUGH
TAU 48 AND A CONTINUED CLIMB THROUGH TAU 96 AFTER WHICH GENERAL
STAGNATION THROUGH THE FORECAST PERIOD. THERE IS A ROUGHLY 35KT
SPREAD IN THE GUIDANCE BY TAU 120. FOR THIS REASON THE JTWC
INTENSITY FORECAST IS PLACED INITIALLY WITH HIGH CONFIDENCE AND
WITH MEDIUM CONFIDENCE THEREAFTER.

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