WDPN33 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.0N 123.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 358 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 36 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS A FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH
TROPICAL STORM (TS) 11W (CO-MAY). THE SYSTEM IS CURRENTLY
TRANSITING AT AN IMPRESSIVE 36 KT SPEED OVER WATER LEAVING BEHIND
THE CENTRAL CONVECTION, DUE TO PERSISTENT EASTERLY VERTICAL WIND
SHEAR (VWS). TS 11W WAS ABLE TO ACCELERATE SIGNIFICANTLY, WITH THE
ASSISTANCE OF A NEAR EQUATORIAL RIDGE LOCATED TO THE SOUTHEAST, AS
WELL AS THE TIGHT GRADIENT DRIVEN BY THE POSITIONING OF A LARGE
CYCLONIC CIRCULATION CENTERED JUST EAST OF TAIWAN. THE INITIAL
POSITION IS DETERMINED WITH HIGH CONFIDENCE, SUPPORTED BY ANIMATED
SHORTWAVE INFRARED IMAGERY SHOWING THE EXPOSED LLCC, AND FURTHER
CORROBORATED BY A 251211Z METOP-B ASCAT PASS. INITIAL INTENSITY IS
ESTIMATED AT 35 KTS WITH HIGH CONFIDENCE, AND IS DERIVED FROM THE
AFOREMENTIONED SCATTEROMETER PASS, COMBINED WITH SUBJECTIVE DVORAK
ESTIMATES AND OBJECTIVE INTENSITY GUIDANCE LISTED BELOW. ADDITIONAL
ENVIRONMENTAL ANALYSIS REVEALS DRY MID-LEVEL AIR ALONG THE PATH OF
TS 11W, MODERATE TO HIGH (15-20 KTS) VERTICAL WIND SHEAR REGION
IMMEDIATELY TO THE EAST OF THE TRACK AND WEAK UPPER-LEVEL OUTFLOW.
PREDOMINANTLY UNFAVORABLE CONDITIONS ARE OFFSET HOWEVER BY WARM
(29-30 C) SEA SURFACE TEMPERATURES (SST).

INITIAL WIND RADII BASIS: 251211Z METOP-B ASCAT PASS

CURRENT STEERING MECHANISM: NEAR EQUATORIAL RIDGE (NER) TO THE
SOUTHEAST, AS WELL AS LARGE CYCLONIC CIRCULATION CENTERED JUST EAST
OF TAIWAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 44 KTS AT 251102Z
   CIMSS ADT: 32 KTS AT 250840Z
   CIMSS AIDT: 34 KTS AT 250840Z
   CIMSS D-PRINT: 25 KTS AT 251300Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: EASTERLY DEEP-LAYER VERTICAL WIND SHEAR AND DRY
AIR ENTRAINMENT

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 11W IS FORECAST TO CONTINUE ITS VERY FAST
TRANSIT ALONG THE NORTHWESTERN PERIPHERY OF A NER ANCHORED TO THE
SOUTHEAST, SIMULTANEOUSLY UNDER THE INFLUENCE OF A BROADER CYCLONIC
CIRCULATION EXTENDING ACROSS THE REGION. DURING THE NEXT 12 HOURS,
THE SYSTEM WILL INTERACT WITH CURRENTLY DISSIPATING TROPICAL
DEPRESSION (TD) 10W LOCATED TO THE NORTH OF TAIWAN. A VERY WEAK 
FUJIWHARA EFFECT IS ANTICIPATED, THOUGH LIMITED IN MAGNITUDE DUE TO 
THE COMPARATIVELY LOW VORTEX INTENSITIES OF BOTH SYSTEMS. MODEL 
GUIDANCE INDICATES A POTENTIAL FOR TS 11W TRACK DEFLECTION TO THE 
WEST, HOWEVER IF TD 10W DISSIPATES COMPLETELY FASTER THAN
ANTICIPATED, THIS EFFECT MAY BE MINIMAL. SIMULTANEOUSLY, THE BROAD
SYNOPTIC-SCALE CYCLONIC ROTATION CENTERED JUST EAST OF TAIWAN IS
FORECAST TO REORIENT FROM A SOUTHWEST-NORTHEAST AXIS TO ONE RESEMBLING 
A REVERSE-ORIENTED MONSOON TROUGH. THIS ENVIRONMENT WILL CONTRIBUTE TO 
AN EASTWARD RECURVATURE OF TS 11W BY THE TIME IT BEGINS TO WEAKEN 
BELOW 25 KTS. DISSIPATION IS ANTICIPATED TO COMPLETE BY TAU 36, AS THE 
LLCC FURTHER SHALLOWS OUT AND BECOMES FULLY EMBEDDED WITHIN THE DEEP-
LAYER WESTERLY FLOW REGIME, RESULTING IN ABSORPTION INTO THE LARGER 
SYNOPTIC-SCALE ENVIRONMENT.

MODEL DISCUSSION: NUMERICAL TRACK MODEL GUIDANCE IS IN GENERAL
AGREEMENT THROUGH TAU 24, WITH GALWEM AS A PRIMARY OUTLIER, PREDICTING 
AN IMMEDIATE NORTH-NORTHEASTWARD TRACK. THE REMAINING AVAILABLE 
CONSENSUS MEMBERS ARE CONTAINED WITHIN A TIGHT 60-65 NM CROSS-TRACK 
SPREAD ENVELOPE AT TAU 24. CONSISTENT MODEL OUTPUTS INDICATE A 
NORTHEASTWARD MOTION FOLLOWED BY DECELERATION AND EVENTUAL VORTEX 
DISSIPATION, RESULTING IN INCREASED TRACK DIVERGENCE THEREAFTER. THE 
JTWC OFFICIAL TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE AND 
CLOSELY FOLLOWS THE MULTI-MODEL CONSENSUS ENVELOPE, WITH A SLIGHT BIAS 
TOWARD THE GFS SOLUTION BEYOND TAU 24, WHICH IS ASSESSED TO MORE 
ACCURATELY REPRESENT THE EVOLVING SYNOPTIC STEERING PATTERN. INTENSITY 
GUIDANCE IS ALSO CONVERGING ON A WEAKENING TREND THROUGH THE FORECAST 
PERIOD, SUPPORTED BY ALL CONSENSUS SOLUTIONS. AROUND TAU 36 HOWEVER,
UNCERTAINTY INCREASES, WITH SOME SOLUTIONS DEPICTING RE-
INTENSIFICATION, LIKELY A RESULT OF MODEL VORTEX HANDOFF TO A NEW
CIRCULATION DEVELOPING NEAR OKINAWA, POTENTIALLY MISINTERPRETED AS
CONTINUITY OF THE EXISTING SYSTEM.

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