WDPN31 PGTW 240300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (MINDULLE) WARNING 
NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.6N 140.9E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 239 NM WEST-NORTHWEST OF ANDERSEN AFB,
GUAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM
CONTINUED TO SLOWLY CONSOLIDATE AS THE CIRCULATION HAS BECOME MORE
DEFINED AND FEEDER BANDS HAVE DEEPENED AND WRAPPED TIGHTER INTO THE
CENTER. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED
ON THE EVOLVING CIRCULATION IN THE MSI LOOP. THE INITIAL INTENSITY
OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE HIGH END
OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SLIGHT
IMPROVEMENT IN 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: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 44 KTS AT 232140Z
   CIMSS ADT: 39 KTS AT 232340Z

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: MEDIUM

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 130KTS BY TAU 72 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 LOOSE AGREEMENT WITH THE
TRACK FORECAST WITH THE SPREAD REACHING 545 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 AFTER TAU 72 TO OFFSET THE LEFT
OUTLIERS. CONSEQUENTLY, 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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