WDPN31 PGTW 232100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (MINDULLE) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.1N 141.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 182 NM WEST OF ANDERSEN AFB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
CONTINUED TO CONSOLIDATE AS EVIDENCED BY IMPROVED WRAP ON THE RAIN
BANDS TO THE NORTHEAST AND SOUTHWEST FEEDING INTO AN OBSCURED LOW
LEVEL  CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON A MICROWAVE LLC FEATURE IN THE 231601Z
GCOMW AMSR2 37GHZ IMAGE. THE INITIAL INTENSITY OF 45 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON AN OVERALL ASSESSMENT OF
AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SLIGHT
IMPROVEMENT OF THE SYSTEM. ENVIRONMENTAL ANALYSIS INDICATES HIGHLY
FAVORABLE CONDITIONS WITH LOW VWS, STRONG UPPER LEVEL OUTFLOW, AND
VERY WARM SSTS IN THE PHILIPPINE SEA. THE CYCLONE IS TRACKING ALONG
THE SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED STR TO THE
NORTHEAST.

INITIAL WIND RADII BASIS: RECENT SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF THE
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 35 KTS AT 231430Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 0-5 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 20W WILL GENERALLY CONTINUE ON ITS CURRENT
TRACK UNDER THE STR UP TO TAU 96; AFTERWARD, THE SYSTEM WILL TURN
MORE NORTHWARD AS IT BEGINS TO ROUND THE WESTERN EDGE OF THE STR. 
THE FAVORABLE ENVIRONMENT WILL FUEL GRADUAL THEN RAPID 
INTENSIFICATION TO A PEAK OF 125KTS BY TAU 96 AS INCREASED POLEWARD 
OUTFLOW IS ANTICIPATED IN CONJUNCTION WITH INITIAL EXPOSURE TO THE 
STRONG WESTERLIES AHEAD OF A MIDLATITUDE TROUGH. AFTERWARD, 
INCREASING VWS WILL BEGIN TO WEAKEN THE SYSTEM, DOWN TO 115KTS BY 
TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY LOOSE AGREEMENT WITH
THE TRACK FORECAST WITH THE SPREAD REACHING 704 NM BY TAU 120 MAINLY 
CAUSED BY A TIGHT CLUSTER OF TRACKERS INCLUDING UEMN, EGRR, AND AFUM 
THAT ARE ON THE EXTREME LEFT MARGIN OF THE MODEL ENVELOPE. IN VIEW 
OF THIS, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST UP TO 
TAU 72 AND LOW CONFIDENCE AFTERWARD, PROPORTIONALLY ADJUSTED TO THE 
RIGHT OF THE MODEL CONSENSUS TO OFFSET THE LEFT OUTLIERS. THERE IS 
ALSO MEDIUM CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 72 AND 
LOW 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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