WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BEBINCA) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.4N 140.0E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 358 NM NORTHWEST OF NAVSTA GUAM
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN IMPROVED
CENTRAL DENSE OVERCAST (CDO) WITH AN EXTENSIVE FIELD OF DEEP
CONVECTION EXTENDING EASTWARD. A RECENT PARTIAL 112350Z ASCAT-B
SCATTEROMETRY IMAGE SHOWS A SMALL CONSOLIDATING CIRCULATION HAS
CENTERED ITSELF BENEATH THE EXPANSIVE CDO ABOVE. THOUGH STILL
HIGHLY ASYMMETRIC, THE WIND FIELD CONSISTS OF 40KT WINDS EXTENDING
OUT OF THE EASTERN PERIPHERY AND WRAPPING ALONG THE POLEWARD
QUADRANT WHILE THE SOUTHERN AND WESTERN SEMICIRCLES REMAIN DEVOID
OF STORM FORCE WINDS. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON MSI AND SCATTEROMETERY IMAGERY. THE INITIAL
INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
AGENCY DVORAK INTENSITY ESTIMATES INDICATING 45-55KTS WHILE CIMSS
ADT REMAINS HIGHER AT 59KTS.

INITIAL WIND RADII BASIS: PARTIAL 112350Z ASCAT-B SCATTEROMETRY
IMAGE

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 59KT KTS AT 0030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE DUAL-CHANNEL

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: RECENT ASCAT IMAGERY INDICATES THE
LLCC HAS CONSOLIDATED NORTH-EASTWARD AND BENEATH THE CDO. CPA TO
OKINAWA HAS THEREFOR OPENED SLIGHTLY. 

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 OKINAWA, BEFORE
TRACKING INTO MAINLAND CHINA.  RECENT PARTIAL SCATTEROMETERY
INDICATES THE CIRCULATION HAS CONSOLIDATES NORTHWESTWARD AND
BENEATH THE CDO. THIS WILL SERVE TO ALIGN THE VERTICAL PROFILE OF
THE SYSTEM AND LIKELY LEAD TO GREATER INTENSIFICATION POTENTIAL.
THROUGH TAU 36, THE ENVIRONMENTAL CONDITIONS, WILL FUEL 14W TO
AROUND 65KTS. 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 INTENSIFY TO 105KTS AND POSSIBLY HIGHER BY
TAU 96. AS THE SYSTEM IS FORCED FURTHER WESTWARD BY THE STR, 14W
WILL CONTINUE TO INTENSIFY BEFORE MAKING LANDFALL SOUTH OF SHANGHAI
CHINA AND PROCEEDING INLAND THROUGH THE FORECAST PERIOD. AFTER TAU
36, 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 A 100NM SPREAD IN SOLUTIONS. THIS SPREADING INCREASES
TO 150NM 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 SHEAR AND DRY AIR INTERFERENCE, TAU 36-96 IS STRONG
INTENSIFICATION DUE TO NEGLIGIBLE LIMITING FACTORS AND LANDFALL
THEREAFTER. THIS APPROACH IS MODERATELY SUPPORTED THROUGH TAU 72
AND DEVIATES 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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