WDPN32 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (DANAS) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.8N 118.0E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 230 NM EAST-SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
PRONOUNCED DEEP CONVECTIVE BANDING SURROUNDING A PERSISTENT CENTRAL
DENSE OVERCAST, FULLY OBSCURING THE LOW-LEVEL CIRCULATION CENTER
(LLCC) OF TROPICAL STORM (TS) 05W (DANAS). THE INITIAL STORM
POSITION IS ASSESSED WITH HIGH CONFIDENCE THROUGH POSITION
EXTRAPOLATION FROM A WELL-DEFINED MICROWAVE EYE PRESENT IN A
051008Z GPM GMI 37 GHZ PASS. THE INITIAL INTENSITY ESTIMATE OF 60
KTS IS LAID WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK
ESTIMATES AND OBJECTIVE AIDS LISTED BELOW. ENVIRONMENTAL ANALYSIS
INDICATES HIGHLY FAVORABLE CONDITIONS FOR CONTINUED INTENSIFICATION. 
KEY INDICATORS INCLUDE ROBUST RADIAL UPPER-LEVEL OUTFLOW, LOW (5-10 
KTS) VERTICAL WIND SHEAR (VWS), WARM (29-30 C) SEA SURFACE 
TEMPERATURES (SST), AS WELL AS CONTINUOUSLY COLD (-83 C) CLOUD TOPS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT WITH A
SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH AND A
NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.5 - 77 KTS
   DEMS: T3.5 - 55 KTS
   CIMSS SATCON: 56 KTS AT 051200Z
   CIMSS ADT: 55 KTS AT 051200Z
   CIMSS AIDT: 54 KTS AT 051200Z
   CIMSS D-PRINT: 57 KTS AT 051200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   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 05W IS FORECAST TO TRACK GENERALLY
NORTHEASTWARD OVER THE NEXT 48 HOURS. A COMPETING STEERING FLOW
ENVIRONMENT IS INDUCING A SLOW AND FLUCTUATING TRANSLATIONAL
MOTION, AVERAGING APPROXIMATELY 3 KTS, AS THE SYSTEM APPROACHES THE
TAIWAN STRAIT. OVER THE NEXT 12-24 HOURS, STRENGTHENING OF THE NER
TO THE EAST IS EXPECTED TO BECOME THE DOMINANT STEERING INFLUENCE,
GUIDING TS 05W NORTHEASTWARD. BY APPROXIMATELY TAU 48, THE NER IS
FORECAST TO WEAKEN AND RETROGRESS SOUTHWARD, WHILE THE SUBTROPICAL
RIDGE (STR) TO THE NORTH AMPLIFIES AND EXTENDS EAST-SOUTHEASTWARD,
PROMPTING TS 05W TO MAKE A SHARP WESTWARD TURN TOWARD MAINLAND
CHINA. RAPID INTENSIFICATION (RI) IS LIKELY WITHIN THE NEXT 24-36
HOURS, SUPPORTED BY DYNAMICAL AND STATISTICAL MODEL GUIDANCE,
INCLUDING RI-SPECIFIC AIDS SUCH AS FRIA, RIDE, RIPA, DTOP, AND
RICN. THIS INTENSIFICATION IS CONTINGENT ON THE SYSTEM REMAINING
OVER WARM WATERS OF THE TAIWAN STRAIT. BETWEEN TAU 48 AND 72, THE
SYSTEM IS FORECAST TO MAKE LANDFALL OVER MAINLAND CHINA, LIKELY
SOUTH OF WENZHOU, AND BEGIN INTERACTING WITH TERRAIN, INITIATING A
PHASE OF RAPID WEAKENING. COMPLETE DISSIPATION OVER LAND IS
PROJECTED BY TAU 96. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE DEMONSTRATES
MODERATE CONSENSUS, WITH A CROSS-TRACK SPREAD OF APPROXIMATELY 30
NM BY TAU 36 WHILE THE SYSTEM TRANSITS THE TAIWAN STRAIT,
INCREASING TO 60 NM BEYOND THAT POINT. UKMET (EGRI) REMAINS A
NOTABLE OUTLIER, FORECASTING A SOUTHERN TAIWAN LANDFALL NEAR TAU
36. BEYOND TAU 48, MODEL SPREAD INCREASES, AND CONFIDENCE IN THE
EXACT LANDFALL LOCATION DIMINISHES. INTENSITY GUIDANCE IS BROADLY
ALIGNED IN TERMS OF INTENSIFICATION AND SUBSEQUENT WEAKENING
TIMELINES, THOUGH VARIANCE IN PEAK INTENSITY ESTIMATES REMAINS
NOTABLE AND CURRENTLY RANGING UP TO 40 KTS. THERE IS STRONG
AGREEMENT AMONG CONSENSUS MEMBERS REGARDING SYSTEM WEAKENING BELOW
WARNING CRITERIA BY OR BEFORE TAU 96. OF NOTE, CURRENT CONSENSUS
TRACK, AND THEREFORE JTWC FORECAST, MARGINALLY SHIFTED TOWARDS
TAIWAN SINCE LAST FORECAST, INDICATING A POTENTIAL WEAKER IMPACT
FROM THE NER. INCREASED INTERACTION OF THE WIND FIELD WITH
TAIWANESE MOUNTAIN RANGES WOULD SIGNIFICANTLY DECREASE PEAK
INTENSITY ESTIMATES. OVERALL, WHILE TRACK AND INTENSITY GUIDANCE
ARE GENERALLY COHERENT, UNCERTAINTIES REMAIN REGARDING LAND
INTERACTION TIMING AND ITS EFFECT ON THE INTENSIFICATION RATE.
CONSEQUENTLY, THE JTWC INTENSITY FORECAST IS ASSIGNED MEDIUM
CONFIDENCE.


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