WDPN31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BEBINCA) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9N 140.1E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 301 NM WEST-NORTHWEST OF NAVSTA GUAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
QUASI-CENTRAL DENSE OVERCAST (CDO) THAT IS FULLY OBSCURING THE LOW
LEVEL CIRCULATION CENTER. FORTUNATELY AN 111627Z AMSR2 89GHZ
MICROWAVE IMAGE REVEALS AN EXTENSIVE NETWORK OF LOW LEVEL CLOUD
LINES TO THE WEST AND SOUTH OF THE LLCC. PREVIOUS SCATTEROMETERY
PASSES INDICATED AN ELONGATED CIRCULATION THAT WAS STRUGGLING TO
CONSOLIDATE, THIS PERSISTENT CONVECTIVE CANOPY MAY BE A PREAMBLE
FOR FUTURE INTENSIFICATION. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON EIR AND AMSR2 IMAGERY. THE INITIAL
INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
AGENCY DVORAK INTENSITY ESTIMATES WHICH INDICATE 35-45KTS AND CIMSS
DPRINT WHICH SHOWS 37KTS. CIMSS ADT AND AIDT REMAIN A BIT HIGH
AT 50-57KTS, DUE IN PART TO THE INCORRECT UTILIZATION OF THE
UNIFORM CDO METHOD VIS THE SHEAR METHOD.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP LAYER
SUB-TROPICAL RIDGE (STR) ENTRENCHED IN MIDPAC. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 57 KTS AT 111910Z

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

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: TROPICAL STORM 14W (BEBINCA) IS FORECASTED TO
CONTINUE ALONG THE WESTERN PERIPHERY OF THE STR CENTERED TO THE
EAST. THIS RIDGE WILL CREATE A GRADUAL ARC IN THE FORECAST TRACK
THAT HAS PERSISTENTLY INCLUDED A CLOSE CPA TO KADENA AB, BEFORE
TRACKING INTO MAINLAND CHINA.  UNFORTUNATELY, RECENT SCATTEROMETERY
PASSES INDICATED THE CIRCULATION HAD YET TO CONSOLIDATE ITS WIND
FIELD AND WITH THE DEEP CONVECTIVE CANOPY IN PLACE, PRECISE
LOCALIZATION IS DIFFICULT. AS THE CIRCULATION MATURES AND
CONSOLIDATES, THE LLCC COULD FORM ANYWHERE ALONG THE MAJOR AXIS OF
THE CURRENT ELLIPSE EVIDENT IN THE 111217Z ASCAT-C SCATTEROMETERY
PASS. WHILE THIS SHIFT MAY ONLY BE 15-20NM, THE DOWN STREAM
IMPLICATIONS MAY BE LARGER IN MAGNITUDE. THE GOOD NEWS IS, AS
PREVIOUSLY STATED, THIS UNCERTAINTY IS FORECASTED TO BE NEGATED AS
THE SYSTEM CONTINUES INTENSIFYING. THROUGH TAU 36, THE
ENVIRONMENTAL CONDITIONS, WHILE NOT OPULENT, WILL FUEL 14W TO
AROUND 55KTS. LOW VERTICAL WIND SHEAR AND WARM SSTS WILL LARGELY
OVERPOWER THE SIDE EFFECTS OF THE UPPER LEVEL LOW SITUATED TO THE
SYSTEMS NORTHWEST, MAINLY SUBSIDENCE AND DRY AIR ENTRAINMENT.
BEYOND TAU 36, THE SYSTEM IS FORECASTED TO FINALLY ESTABLISH A DEEP
MOISTURE SIGNATURE, TOGETHER WITH LOW VERTICAL WIND SHEAR AND WARM
SSTS, 14W WILL RAPIDLY ACHIEVE TYPHOON STATUS AND BEYOND, REACHING
95KTS BY TAU 72. AS THE SYSTEM IS FORCED FURTHER WESTWARD BY THE
STR, 14W WILL PEAK IN INTENSITY NEAR 110-115KTS AND POSSIBLY HIGHER
BEFORE MAKING LANDFALL SOUTH OF SHANGHAI CHINA AND PROCEEDING
INLAND THROUGH THE FORECAST PERIOD. THROUGH THIS ENTIRE FORECAST,
THE ONE FACTOR THAT IS LACKING IS ANY NOTABLE UPPER LEVEL VENTING.
THOUGH THERE IS NO INDICATIONS OF ONE SETTING UP AT THIS TIME, IF
14W TAPS INTO A SIGNIFICANT OUTFLOW CHANNEL, THIS SYSTEMS INTENSITY
COULD RAPIDLY GET OUT OF HAND.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT THROUGH
TAU 48 WITH AN 80NM SPREAD IN SOLUTIONS. THIS SPREADING INCREASES
TO 118NM NEAR THE SYSTEMS CPA TO KADENA AB. AFTER TAU 72, MEMBERS
SPREADING BOTH POLEWARD AND EQUATORWARD WORSEN THROUGH TAU 120. FOR
THIS REASON THE JTWC FORECAST TRACK IS PLACED WITH OVERALL MEDIUM
CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE INDICATES A WIDE
RANGE OF SOLUTIONS, WITH NUMEROUS RAPID INTENSIFICATION (RI) AIDS
TRIGGERING WHILE MEMBERS LIKE CMC AND COAMPS-TC NAVGEM INDICATE
NEGLIGIBLE INTENSIFICATION THROUGH THE FORECAST PERIOD. JTWC IS
PHASING THE INTENSIFICATION IN THREE PARTS. TAU 0-36 IS MODERATE
DUE TO THE DRY AIR INTERFERENCE, TAU 36-96 IS STRONG
INTENSIFICATION DUE TO NEGLIGIBLE LIMITING FACTORS AND LANDFALL
THEREAFTER. THIS APPROACH IS WELL SUPPORTED THROUGH TAU 72 BY MOST
MEMBERS AND DEVIATES SLIGHTLY FROM THE CONSENSUS AFTER TAU 72. FOR
THIS REASON THE JTWC INTENSITY FORECAST IS PLACED INITIALLY WITH
MEDIUM CONFIDENCE AND WITH LOW CONFIDENCE THEREAFTER.

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