WDPN32 PGTW 092100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (PODUL) WARNING NR 
012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.5N 140.2E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 207 NM SOUTH-SOUTHWEST OF IWO TO
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LLCC WITH LOW LEVEL CLOUD LINES APPARENT ON THE POLEWARD
SIDE. A DEEP CONVECTIVE PLUME SHEARED TO THE SOUTH IS PRODUCING
WEAK RADIAL OUTFLOW AND MODERATE EQUATORWARD OUTFLOW WITH
TRANSVERSE BANDING EVIDENT THROUGHOUT. THE CDO PRESENTS AN OVERALL
UNIFORM APPEARANCE WITH LITTLE TREND IN THE CLOUD TOP TEMPERATURES
OVER THE PAST SIX HOURS. A 1649UTC AMSR2 IMAGE INDICATED THE
STRONGEST SURFACE WINDS IN THE SOUTHEAST QUADRANT AND WRAPPING
ALONG THE EASTERN PERIPHERY, THOUGH THE VELOCITIES ARE SUSPECT DUE
TO THE ICE CONTAMINATION NOTED EARLIER. THE INITIAL INTENSITY OF 55
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A COMBINATION OF
AGENCY SUBJECTIVE AND OBJECTIVE INTENSITY AIDS.

INITIAL WIND RADII BASIS: SAR DATA 

CURRENT STEERING MECHANISM: WESTERN EXTENSION OF THE PACIFIC
SUBTROPICAL RIDGE

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 48 KTS AT 091556Z
   CIMSS ADT: 53 KTS AT 091730Z
   CIMSS AIDT: 48 KTS AT 091730Z
   CIMSS D-MINT: 58 KTS AT 091651Z
   CIMSS D-PRINT: 63 KTS AT 091830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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: TS 16W WILL MAINTAIN A WESTWARD TRAJECTORY
WITH A SLIGHT ACCELERATION IN THE FORWARD SPEEDS AS A BONIN HIGH
DEVELOPS AND ESTABLISHES CONTROL OF THE STEERING. THE VERTICAL WIND
SHEAR HAS RECENTLY INCREASED AND WILL CONTINUE TO INCREASE THROUGH
TAU 36, WHICH IS ONE OF THE MAIN FACTORS WORKING AGAINST
INTENSIFICATION. DESPITE THAT, THE SYSTEM IS EXPECTED TO REACH PEAK
INTENSITY AT TAU 36. AFTER THAT TIME, DRY AIR FROM THE NORTH WILL
BECOME MORE OF A FACTOR AS THE BONIN HIGH SETS UP. THIS DRYING
TREND WILL JEOPARDIZE THE INTEGRITY OF THE VORTEX AND LEAD TO A
GRADUAL DECLINE AS IT MAKES LANDFALL IN CHINA AFTER TAU 96,
DISSIPATING BY TAU 120.

MODEL DISCUSSION: TRACK AIDS ARE IN TIGHT AGREEMENT THROUGH TAU 72
WITH THE WESTWARD TRACK BUT DIVERGE INTO A WIDER SPREAD THEREAFTER.
THE JTWC FORECAST LIES SLIGHTLY SOUTH OF THE CONSENSUS DUE TO THE
HIGHER SKILL MODELS ALSO LYING SOUTH OF THE MEAN. THE INTENSITY
AIDS DIVERGE ON THE OVERALL TREND FOR THE FIRST 72 HOURS, WITH
OCEAN-COUPLED MODELS INDICATING INTENSIFICATION AND THE BULK OF
GUIDANCE KEEPING THE INTENSITY RELATIVELY FLATLINED UNTIL A GRADUAL
DECAY COMMENCES AFTER TAU 72. DETERMINISTIC MODELS SHOW A SLIGHT
OSCILLATION OF THE SURFACE PRESSURE DURING THE PERIOD OF
UNCERTAINTY. THE JTWC FORECAST ACCOUNTS FOR THE UNCERTAINTY BY
KEEPING THE INTENSITY FORECAST ON THE HIGHER SIDE OF THE CONSENSUS
THROUGH TAU 48.

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