WDPN31 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.3N 109.9E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 94 NM EAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A RAGGED
DEVELOPING SYSTEM IN THE SOUTH CHINA SEA WITH FLARING CONVECTION
NEAR THE CENTRAL DENSE OVERCAST (CDO) AND A FRAGMENTED FORMATIVE
BAND LOOSELY WRAPPING TOWARD THE CDO THAT IS OBSCURING THE LOW
LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A WEAK BUT DISCERNIBLE MICROWAVE LLC IN THE
171019Z SSMIS 91GHZ COLORED IMAGE. THE INITIAL INTENSITY OF 25KTS
IS BASED ON THE DVORAK ESTIMATES OF T1.5 FROM PGTW, KNES, AND RJTD
AND SUPPORTED BY A 170900Z SHIP OBSERVATION 150NM TO THE NORTHWEST.
ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW VWS
AND WARM SST TEMPERED BY WEAK RADIAL OUTFLOW AND PROXIMITY TO LAND.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: LOW REFLECTION OF A SUBTROPICAL RIDGE
(STR) TO THE EAST-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   DEMS: T1.0 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: UNDER THE STEERING INFLUENCE OF THE STR TO THE
ENE, TD 16W WILL CONTINUE TO TRACK NORTHWESTWARD TOWARD THE GULF OF
TONKIN. AFTER TAU 48, A SECONDARY, SHALLOW STR APPROACHING FROM THE
WEST WILL COMPETE FOR STEERING AND FORCE THE CYCLONE IN A
QUASI-STATIONARY (QS) MODE BEFORE SLOWLY DRIVING IT SOUTHWARD. THE
MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL A MODEST INTENSIFICATION
TO A PEAK 0F 40KTS BY TAU 48. AFTERWARD, LAND INTERFERENCE FROM
NORTHERN VIETNAM TO THE WEST AND HAINAN ISLAND TO THE EAST PLUS SST
COOLING DUE TO CYCLONIC UPWELLING DUE TO THE QS STORM MOTION WILL
GRADUALLY WEAKEN THE SYSTEM DOWN TO 25KTS BY TAU 120.  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT UP
TO TAU 48 THEN DIVERGE SIGNIFICANTLY AFTERWARD AS THE MODELS
DIVERGE ALONG AND ACROSS TRACK DURING THE QS PHASE AND SLOW SOUTHWARD 
DRIFT, LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK AND INTENSITY 
FORECASTS UP TO TAU 72, THEN LOW CONFIDENCE AFTERWARD. 

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