WDPN32 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR 
013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.6N 138.7E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 240 NM SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SHEARED
AND SHRINKING CENTRAL DENSE OVERCAST (CDO) FEATURE THAT IS
PRODUCING MODERATE EQUATORWARD OUTFLOW WITH TRANSVERSE BANDING. THE
WEAK RADIAL OUTFLOW OBSERVED IN THE PREVIOUS ANALYSIS HAS WANED IN
THE PRESENCE OF INCREASINGLY UNFAVORABLE VERTICAL WIND SHEAR.
ALTHOUGH PULSING CONVECTION CONTINUES NEAR THE PARTIALLY EXPOSED
LOW LEVEL CIRCULATION CENTER (LLCC), THE CLOUD TOP TEMPERATURES
HAVE SHOWN SIGNS OF WARMING. A 092303Z GMI 37 GHZ IMAGE REVEALED AN
INCIPIENT, PARTIAL MICROWAVE EYE FORMING WITHIN THE HEAVILY SHEARED
CONVECTION, AND WAS USED TO ASSESS THE POSITION WITH HIGH
CONFIDENCE. MORE RECENT SCATTEROMETRY DATA SUPPORTS THE INITIAL
POSITION. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON A BLEND OF OBJECTIVE ESTIMATES, SUPPORTED BY
AGENCY FIXES, PERSISTENCE, AND THE PARTIAL MICROWAVE EYE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN EXTENSION OF THE PACIFIC
SUBTROPICAL RIDGE

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.5 - 77 KTS
   RCTP: T4.0 - 65 KTS
   CIMSS ADT: 53 KTS AT 092030Z
   CIMSS AIDT: 49 KTS AT 092030Z
   CIMSS D-MINT: 55 KTS AT 092303Z
   CIMSS D-PRINT: 59 KTS AT 092300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-30 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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 16W WILL CONTINUE TO ENCOUNTER WARM SSTS
ALONG ITS WESTWARD TRACK BUT WILL STRUGGLE TO DEVELOP ANY FURTHER
DUE TO INCREASING VWS. THE STEERING RIDGE WILL UNDERGO SOME
VARIATIONS IN SHAPE AND STRENGTH THROUGHOUT THE FORECAST PERIOD AS
A BONIN HIGH SETS UP NEAR JAPAN, AND THIS WILL CONTINUE TO GENERATE
A SOURCE OF DRY AIR AND STRONG VWS ALONG THE POLEWARD SIDE. A
MINORITY OF MODELS INDICATE A BRIEF IMPROVEMENT IN DIVERGENCE ALOFT
WILL OCCUR NEAR TAU 36, RESULTING IN A SLIGHT INCREASE OF PODUL'S
INTENSITY. OVERALL, HOWEVER, ANY FURTHER INTENSIFICATION OF THE
SYSTEM WILL BE LIMITED BY THE INCREASINGLY UNFAVORABLE ENVIRONMENT.
A SLIGHT SOUTHWARD SHIFT IN THE TRACK FORECAST INTRODUCES POSSIBLE
LAND INTERACTION WITH TAIWAN BETWEEN TAU 72 AND TAU 96, WHICH COULD
RESULT IN GREATER UNCERTAINTIES IN THE LATER TAUS. ULTIMATELY,
PODUL IS EXPECTED TO ARRIVE IN CHINA BY TAU 96, LEADING TO A
DISSIPATION OVER LAND BY TAU 120.

MODEL DISCUSSION: THE JTWC TRACK FORECAST STICKS CLOSE TO THE
MULTI-MODEL CONSENSUS EARLY ON, BUT IS HEDGED ON THE SOUTH SIDE OF
THE CONSENSUS WITH THE BULK OF THE RELIABLE MODEL GUIDANCE.
INTERACTION WITH TAIWAN INTRODUCES LARGE UNCERTAINTIES IN THE TRACK
FORECAST, RESULTING IN LOW CONFIDENCE. THE INTENSITY AIDS ARE IN
BETTER AGREEMENT WITH THE INTENSITY PLATEAU THROUGH TAU 24. BOTH
HAFS AND COAMPS-TC INDICATE A MODEST INTENSIFICATION AFTER TAU 24,
BUT HAVE REDUCED THE MAGNITUDE OF THE PEAKS EXPECTED IN EARLIER
RUNS. BETWEEN TAU 48 AND TAU 72, MOST GUIDANCE COMES INTO AGREEMENT
WITH A GRADUAL WEAKENING TREND. THE JTWC FORECAST IS HEDGED ON THE
HIGHER SIDE OF THE CONSENSUS TO ACCOUNT FOR THE POSSIBLE PEAK AT
TAU 36, BUT THERE IS AN INCREASING LIKELIHOOD THAT THE INTENSITIES
WILL STAGNATE IN THE SHORT-TERM WITH AN EVENTUAL DECLINE THROUGH
THE END OF THE FORECAST. 

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