WDPN31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (MATMO) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.5N 119.4E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 197 NM NORTH-NORTHWEST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 28 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS WELL-
DEFINED MESOSCALE DEEP CONVECTIVE BANDING WRAPPING CYCLONICALLY INTO 
THE LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL STORM (TS) 27W 
(MATMO). THE SYSTEM HAS RECENTLY RE-EMERGED OVER SOUTH CHINA SEA, 
AFTER IT TRANSITED OVER NORTHERN LUZON, PHILIPPINES. TERRAIN-INDUCED 
MODULATION RESULTED IS SLIGHT WEAKENING OF THE CONVECTIVE CORE, BUT 
THE SYSTEM IS ALREADY SHOWING SIGNS OF TIGHT WRAPPING AND 
CONSOLIDATION. SPIRALING FEEDER BANDS BEGIN TO BUILD A CENTRAL DENSE 
OVERCAST (CDO) STRUCTURE. AS THE VORTEX ADVANCES OVER THE SOUTH CHINA 
SEA, IT REMAINS EMBEDDED WITHIN A FAVORABLE SYNOPTIC REGIME 
CHARACTERIZED BY STRONG UPPER-LEVEL DIVERGENCE ENHANCING RADIAL 
OUTFLOW. SEA SURFACE TEMPERATURES (SST) OF 29-30 C, LOW VERTICAL WIND 
SHEAR (VWS) BETWEEN 5-10 KTS, AND A DEEPLY SATURATED TROPOSPHERIC 
COLUMN ARE SUPPORTING MAINTENANCE OF VIGOROUS DEEP CONVECTIVE 
PROCESSES. THE INITIAL POSITION IS ASSIGNED WITH MEDIUM CONFIDENCE 
BASED ON A FUSION OF AGENCY DVORAK FIXES AND PARTIALLY EXPOSED LLCC 
PRESENT IN THE SHORTWAVE INFRARED IMAGERY LOOP. INITIAL INTENSITY IS 
EVALUATED AT 60 KTS WITH MEDIUM CONFIDENCE, CORROBORATED BY OBJECTIVE
SATELLITE-DERIVED INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 53 KTS AT 031130Z
   CIMSS AIDT: 58 KTS AT 031130Z
   CIMSS D-MINT: 61 KTS AT 030813Z
   CIMSS D-PRINT: 49 KTS AT 031200Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 27W IS FORECAST TO MAINTAIN A NORTHWESTWARD
TRAJECTORY UNDER THE INFLUENCE OF A DEEP-LAYERED STR ANCHORED TO
THE NORTH. INTERACTION WITH THE OROGRAPHIC COMPLEXITY OF LUZON HAS
INTRODUCED SOME FRICTIONAL DISRUPTION TO THE BOUNDARY-LAYER INFLOW, 
BUT THE SYSTEM CONTINUES TO DERIVE ENERGY FROM FEEDER BANDS REMAINING 
POSITIONED OVER HIGH OCEAN HEAT CONTENT WATERS, MITIGATING 
SIGNIFICANT STRUCTURAL DEGRADATION. WHILE FAVORABLE ENVIRONMENTAL 
CONDITIONS SUPPORT FURTHER DEEPENING, THE CYCLONE WILL TRACK ALONG 
THE SOUTHERN PERIPHERY OF THE STR AND IS PROJECTED TO APPROACH THE 
CHINESE COAST WITH A PEAK INTENSITY OF 85 KTS AROUND TAU 36. THE 
PRIMARY LANDFALL IS EXPECTED NORTH OF HAINAN ISLAND AND OVER THE 
LEIZHOU PENINSULA JUST BEFORE TAU 48, FOLLOWED BY A SECONDARY 
LANDFALL IN PROXIMITY TO THE CHINA-VIETNAM BORDER BETWEEN TAU 48 AND 
72. SUBSEQUENTLY, THE SYSTEM IS FORECAST TO EXPERIENCE RAPID 
STRUCTURAL DEGRADATION AND WEAKENING DUE TO LAND INTERACTION, 
RESULTING IN DISSIPATION PRIOR TO THE TERMINUS OF THE CURRENT 
FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL PREDICTION GUIDANCE MAINTAINS GOOD 
AGREEMENT REGARDING THE SYNOPTIC-SCALE STEERING PATTERN AND OVERALL 
TRACK EVOLUTION. THE TRACK SPREAD AMONG THE CONSENSUS MEMBERS REMAINS 
LIMITED TO APPROXIMATELY 45 NM PRIOR TO FINAL LANDFALL. THE JTWC 
TRACK FORECAST IS CONSISTENT WITH THE MULTI-MODEL CONSENSUS AND IS 
POSITIONED ALONG THE NORTHERN PERIPHERY OF THE GUIDANCE ENVELOPE.
INTENSITY FORECAST CONFIDENCE IS MEDIUM, ATTRIBUTABLE TO UNCERTAINTY 
IN RE-INTENSIFICATION TIMING AND CHARACTER OVER OPEN WATERS. 
FAVORABLE THERMODYNAMIC PARAMETERS - INCLUDING ELEVATED SST, STRONG 
UPPER-LEVEL DIVERGENCE, AND MINIMAL VWS - WILL PERSIST ACROSS MOST OF 
THE PREDICTED TRACK. A MINOR AND GRADUAL INCREASE IN VWS IS EXPECTED 
SHORTLY AFTER TAU 36, WHICH MAY SLOW DOWN DEVELOPMENT. HOWEVER, THE 
POTENTIAL FOR SHORT-TERM INTENSIFICATION REMAINS ELEVATED, WITH SOME 
RAPID INTENSIFICATION (RI) AIDS (DTOP, RIDE) BEING TRIGGERED. PEAK 
INTENSITY IS FORECAST AROUND TAU 36. ALL DETERMINISTIC INTENSITY 
MODELS PROJECT MAXIMUM WIND SPEEDS BELOW 85 KTS AND INDICATE SHARP 
POST-LANDFALL WEAKENING, SUPPORTING LATER STAGES OF THE INTENSITY 
FORECAST.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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