WDPN31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 16W (SIXTEEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.5N 112.1E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 236 NM EAST-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
WHAT WAS PREVIOUSLY IDENTIFIED AS TWO VORTICITY MAXIMA IN THE SOUTH
CHINA SEA HAVE CONTINUED CONSOLIDATING INTO ONE SYSTEM OVER THE LAST 
SIX HOURS AS DEPICTED IN A CIMSS 850MB VORTICITY ANALYSIS PLACING THE 
PRIMARY VORTICITY MAXIMA IN THE VISCINITY OF THE BEST TRACK POSITION 
WITH A LOBE EXTENDING SOUTHWESTWARD. ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY DEPICTS STRONG SOUTHWESTERLY SUPPORT TO AN ELONGATED 
REGION OF TURNING SOUTHEAST OF HAINAN. CONVECTION HAS BUILT IN THE 
REGION SPANNING FROM THE SOUTHWEST TO THE NORTHEAST, AND STRONG 
POLEWARD OUTFLOW IS APPARENT INTO DIFFLUENT EASTERLY UPPER-LEVEL FLOW. 
THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON THE 
AFOREMENTIONED TURNING IN ANIMATED EIR. THE INITIAL INTENSITY OF 25 
KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON THE AGENCY AND OBJECTIVE 
FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   RJTD: T1.5 - 25 KTS
   CIMSS ADT: 31 KTS AT 181300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   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: TROPICAL DEPRESSION (TD) 16W WILL TRACK
WESTWARD THROUGHOUT THE FORECAST PERIOD WHILE STEERED BY A STR TO
THE NORTH. THE SYSTEM WILL MAKE LANDFALL BETWEEN TAU 24-36 WHERE
ELEVATED TOPOGRAPHY IN VIETNAM WILL INITIATE WEAKENING. THE SYSTEM
WILL REMAIN IN MODERATELY FAVORABLE CONDITIONS FOR INTENSIFCATION
FOR THE FIRST 24 HOURS OF THE FORECAST. THE PRIMARY MITIGATING
FACTOR FOR INTENSIFICATION WILL BE VERTICAL WIND SHEAR THAT WILL
INCREASE TO 15-20KTS BETWEEN TAU 12-24. BETWEEN TAU 24-36, THE
SYSTEM WILL MAKE LANDFALL AND DISSIPATE BY TAU 48.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
REGARDING THE OVERALL TRACK DIRECTION WITH ONLY TWO OUTLIERS: ECMWF, 
WHICH TRACKS NEARLY DUE WEST-NORTHWEST STARTING AT TAU 0, AND UKMET 
WHICH QUICKLY RECURVES AFTER TAU 12. THE JTWC TRACK FORECAST LIES MUCH 
MORE CLOSELY TO GFS, GSM, HAFS-A, AND HWRF. THE INTENSITY GUIDANCE 
AGREES THAT THE INTENSITY WILL PEAK BETWEEN 35-40KTS AT TAU 24 BEFORE 
RAPIDLY DECLINING AFTER LANDFALL.

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