WDPN31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BEBINCA) WARNING NR 
004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.2N 144.4E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 17 NM SOUTHWEST OF NAVSTA GUAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 14W AS CONTINUING TO SLOWLY CONSOLIDATE WITH A
PERSISTENT CENTRAL DENSE OVERCAST (CDO) POSITIONED OVER THE
LOW-LEVEL CIRCULATION CENTER (LLCC). WITH THE ASSOCIATED CDO
OBSCURING THE LLCC, LOCAL GUAM RADAR IMAGERY HAS REVEALED A DEFINED
SURFACE CIRCULATION WITH CURVED CONVECTIVE BANDING EXTENDING
SOUTHWARD FROM THE LLCC AND ISOLATED CONVECTIVE STRUCTURES WRAPPING
CYCLONICALLY THROUGH THE NORTHERN SEMICIRCLE INTO THE SYSTEM'S
WESTERN PERIPHERY. ALTHOUGH THE AFOREMENTIONED RADAR IMAGERY HAS
CONFIRMED SUPPORTIVE CURVED BANDING AROUND A CENTRAL CIRCULATION,
THE LLCC HAS REMAINED FAIRLY ELONGATED OVER THE LAST FEW HOURS.
DESPITE THIS, AN OVERALL IMPROVEMENT OF TS 14W HAS BEEN OBSERVED.
ANIMATED WATER VAPOR IMAGERY ILLUSTRATES A MODERATE UPPER-LEVEL
OUTFLOW PATTERN, WITH AN ADDITIONAL WEAK POLEWARD CHANNEL EXTENDING
TO THE NORTHEAST. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED GUAM RADAR IMAGERY
AND A 101542Z AMSR2 MICROWAVE IMAGE SHOWING CONSOLIDATING LOW-LEVEL
CLOUD BANDS INTO THE ASSESSED LLCC. THE INITIAL INTENSITY IS ASSESSED
WITH HIGH CONFIDENCE BASED ON LOCAL GUAM SURFACE OBSERVATIONS,
CIMSS OBJECTIVE INTENSITY ESTIMATES, AND THE AGENCY ESTIMATES
LISTED BELOW.

INITIAL WIND RADII BASIS: GCOMW1 AMSR2.

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) POSITIONED TO THE EAST AND NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 32 KTS AT 1130Z
   CIMSS ADT: 47 KTS AT 1900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 14W HAS INTENSIFIED TO 35 KTS OVER THE LAST
FEW HOURS AND IS FORECASTED TO STEADILY INTENSIFY TO A MODERATE
STRENGTH TROPICAL STORM INTO TAU 48 DURING THE SYSTEM'S EXPECTED
NORTHWESTWARD TRACK ALONG THE WESTERN PERIPHERY OF A DEEP-LAYER STR
TO THE NORTH AND EAST. BEGINNING AT TAU 48, A MID-LEVEL SWATH OF
DRY AIR WILL ENTRAIN INTO THE SOUTHERN SEMICIRCLE OF TS 14W,
LIMITING THE SYSTEM'S INTENSIFICATION PHASE FOR 24 HOURS. AFTER TAU
72, THE ENVIRONMENTAL CONDITIONS BECOME MORE CONDUCIVE FOR FURTHER
INTENSIFICATION THROUGH TAU 96 AS VERTICAL WIND SHEAR (VWS) REMAINS
MINIMAL OF LESS THAN 15 KTS, SEA SURFACE TEMPERATURES (SST) EXCEED 29
C, AND THE PREVIOUS PHASE OF DRY-AIR ENTRAINMENT INTO THE SOUTHERN
SEMICIRCLE COMES TO AN END. FOLLOWING TAU 72, THE SYSTEM WILL
CONTINUE TO INTENSIFY TO 90 KTS INTO TAU 96, WHILE A SLIGHT
WEAKENING PHASE IS INDICATED BY TAU 120 DUE TO ADDITIONAL IMPACTS
FROM DRY-AIR ENTRAINMENT WRAPPING COMPLETELY AROUND THE WESTERN
SEMICIRCLE OF THE SYSTEM INTO THE END OF THE FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN TIGHT
AGREEMENT THROUGH TAU 72, WITH A MAXIMUM OF AN 85 NM CROSS-TRACK
SPREAD. AFTER TAU 72, MODEL TRACK GUIDANCE DIVERGES SIGNIFICANTLY
WITH INCREASING UNCERTAINTY BETWEEN TAU 96 AND TAU 120. ALTHOUGH
THE JTWC CONSENSUS MEMBERS (CONW) GENERALLY AGREE THAT A NORTHWEST
TRACK IS EXPECTED TOWARD COASTAL CHINA, FEW MEMBERS INDICATE A
RECURVE SCENARIO TOWARD THE KOREAN PENINSULA INTO TAU 120.
PROBABILISTIC GUIDANCE FROM ECMWF (EPS) AND GFS (GEFS) ENSEMBLES
ARE IN GOOD AGREEMENT THROUGH TAU 72 THAT A NORTHWEST TRACK IS
MAINTAINED, HOWEVER, FOLLOWING TAU 72, ENSEMBLE GUIDANCE WITH GEFS
DIVERGES WITH THE AFOREMENTIONED RECURVE TOWARD THE NORTHEAST INTO
THE YELLOW SEA AND THE KOREAN PENINSULA. INTENSITY GUIDANCE REMAINS
IN HIGH CONFIDENCE THROUGH THE FIRST 72 HOURS OF THE FORECAST, AS
STEADY TO MODERATE INTENSIFICATION IS EXPECTED. AFTER TAU 72, THE
INTENSITY GUIDANCE BECOMES LESS RELIABLE AS MESOSCALE GUIDANCE
CONTINUES TO INDICATE RAPID INTENSIFICATION BETWEEN TAU 96 AND TAU
120, WHILE DETERMINISTIC MODEL GUIDANCE DOES NOT. THE JTWC
INTENSITY FORECAST IS ALIGNED MORE CLOSELY WITH THE DETERMINISTIC
MODEL GUIDANCE, AS LIMITATIONS FROM DRY-AIR ENTRAINMENT ARE EXPECTED
BETWEEN TAU 96 AND TAU 120. 

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