WDPN31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (MATMO) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.7N 118.2E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 246 NM NORTHWEST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 
PARTIALLY-EXPOSED, BROAD LOW-LEVEL CIRCULATION CENTER (LLCC), WITH
IMPROVED DEEP CONVECTIVE BANDING WRAPPING TIGHTLY INTO THE LLCC. A
031352Z ASCAT-C IMAGE SHOWS THAT THE SYSTEM TOOK A BRIEF WESTWARD
OR PERHAPS WEST-SOUTHWESTWARD TURN FROM 030600-1200Z BEFORE TURNING
SHARPLY WEST-NORTHWESTWARD OVER THE PAST SIX HOURS. THE INITIAL
WIND RADII HAVE BEEN ADJUSTED TO REFLECT FAIRLY EXTENSIVE GALE-FORCE 
WINDS OVER THE NORTHEAST AND EASTERN QUADRANTS. THE 031349Z MHS 89GHZ 
MICROWAVE IMAGE DEPICTED A BROAD DEFINED LLCC, WITH DEEP CONVECTIVE 
BANDING WRAPPING AROUND THE WESTERN AND EASTERN SEMICIRCLES. THE 
INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED 
ON THE CIMSS AIDT ESTIMATE OF 58 KNOTS, HEDGED SLIGHTLY ABOVE THE 
PGTW SUBJECTIVE INTENSITY ESTIMATE. THE INITIAL POSITION IS PLACED 
WITH MEDIUM CONFIDENCE BASED ON THE EIR SATELLITE IMAGERY.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.5 - 55 KTS
   CIMSS SATCON: 56 KTS AT 031755Z
   CIMSS ADT: 49 KTS AT 031720Z
   CIMSS AIDT: 58 KTS AT 031720Z
   CIMSS D-MINT: 56 KTS AT 031755Z
   CIMSS D-PRINT: 55 KTS AT 031830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 27W IS FORECAST TO TRACK
WEST-NORTHWESTWARD THROUGH THE FORECAST PERIOD ALONG THE SOUTHERN
AND SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE.
TS 27W WILL INTENSIFY STEADILY THROUGH TAU 36 TO A PEAK INTENSITY
OF 85-90 KNOTS. ENVIRONMENTAL CONDITIONS ARE FAVORABLE THROUGH TAU
36, WITH LOW VERTICAL WIND SHEAR, RADIAL OUTFLOW AND WARM SST
VALUES. HOWEVER, THE SYSTEM IS FORECAST TO INTENSIFY AT A NEAR
CLIMATOLOGICAL RATE DUE TO THE BROAD NATURE OF THE LLCC AND LIMITED
TRACK OVER WATER. AFTER TAU 36, THE SYSTEM WILL WEAKEN QUICKLY AS
IT TRACKS OVER SOUTHERN CHINA, WITH DISSIPATION ANTICIPATED BY TAU
96.   

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC MODEL GUIDANCE
REMAINS IN GOOD AGREEMENT THROUGH TAU 72, WITH AN 80-150NM
CROSS-TRACK SPREAD FROM TAU 48 TO TAU 72. AFTER TAU 72, GUIDANCE
DIVERGES LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK FORECAST.
RELIABLE INTENSITY GUIDANCE SUPPORTS A PERIOD OF NEAR-RAPID 
INTENSIFICATION THROUGH TAU 36, WITH PEAK INTENSITIES IN THE 
MESOSCALE GUIDANCE RANGING FROM 75 TO 87 KNOTS. 
  
FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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