WDPN31 PGTW 131500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (SIXTEEN) WARNING 
NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.8N 166.2E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 391 NM SOUTH OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A MIDGET
SYSTEM WITH FLARING CENTRAL CONVECTION THAT IS OFFSET NORTHWARD
FROM AN OBSCURED LOW LEVEL CIRCULATION (LLC). THE CONVECTIVE
PATTERN HAS BEGUN TO CURL, FORMING A NOTCH AROUND THE LOW LEVEL
CIRCULATION; HOWEVER, FORMATIVE BANDS REMAIN SHORT AND FRAGMENTED
AND THE DEGREE OF WRAP IS STILL THE SAME. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE NOTCH FEATURE. THE
INITIAL INTENSITY IS BASED ON AN OVERALL ASSESSMENT OF AGENCY AND
AUTOMATED DVORAK ESTIMATES AND REFLECTS THE OVERALL SUSTAINED 6-HR
CONVECTIVE PATTERN. THE SYSTEM IS IN A MARGINAL ENVIRONMENT
CHARACTERIZED BY STRONG POLEWARD OUTFLOW AND VERY WARM SSTS OFFSET
BY MEDIUM TO STRONG VWS. THE CYCLONE IS TRACKING ALONG THE SOUTHERN
PERIPHERY OF A DEEP LAYERED SUBTROPICAL RIDGE TO THE NORTH.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T1.0 - 25 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 43 KTS AT 131140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   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 REMAIN ON A WESTWARD TRACK UNDER
THE STR UP TO TAU 72; AFTERWARD, IT WILL TURN MORE
WEST-NORTHWESTWARD AS IT BEGINS TO ROUND THE WESTERN EDGE OF THE
STR. THE MARGINAL CONDITIONS, EXACERBATED BY INCREASING VWS AND THE
SUBSIDING EFFECT AS THE SYSTEM CLOSES IN ON A TUTT CELL TO THE
NORTHWEST, WILL TEMPER ANY MEANINGFUL OR SUSTAINED INTENSIFICATION
UP TO TAU 48. AFTERWARD, DECREASING VWS WILL ALLOW FOR GRADUAL
INTENSIFICATION TO 50KTS AT TAU 96 AFTER IT PASSES JUST TO THE
SOUTH OF GUAM, THEN RAPIDLY TO TYPHOON INTENSITY OF 65 KTS BY TAU
120 AS IT ENTERS THE PERENNIALLY WARM AND DEEP OHC WATERS OF THE
PHILIPPINE SEA.  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH A
GRADUAL AND EVEN SPREAD TO MERE 215NM AT TAU 120, WITH THE NVGM THE
NOTABLE OUTLIER ON THE RIGHT MARGIN OF THE ENVELOPE. THE JTWC TRACK
FORECAST IS LAID WITH HIGH CONFIDENCE JUST TO THE LEFT OF THE
MODEL CONSENSUS TO OFFSET NVGM. THE CONFIDENCE IS MEDIUM FOR THE 
INTENSITY FORECAST DUE TO THE UNCERTAINTY IN THE CONVECTIVE 
STRUCTURE OF THE CYCLONE IN THE NEAR TO MID-TERM.

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