WDPN32 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (SAOLA) WARNING NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.8N 123.0E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 175 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: SOUTHWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 09W CONTINUES TO TRACK SLOWLY SOUTHWARD, SKIRTING THE 
NORTHEASTERN COAST OF LUZON. INCREASED INTERACTION WITH THE SIERRA 
MADRE MOUNTAINS (5000 PLUS FOOT PEAKS) AND THE PALANAN POINT REGION 
HAVE LED TO THE WEAKENING OF THE EYEWALL AND CONVECTIVE BANDING OVER 
THE WESTERN SEMICIRCLE AS INDICATED IN ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY. THE SYSTEM HAS RETAINED AN 11 NM EYE SUPPORTING THE 
INITIAL POSITION WITH HIGH CONFIDENCE. A 262233Z SSMIS 91 GHZ MICROWAVE 
IMAGE INDICATES THAT THE OVERALL STRUCTURE HAS REMAINED WELL-ORGANIZED 
WITH SPIRAL BANDING WRAPPING INTO A SYMMETRIC EYEWALL. THE 261800Z 
HAFS-A RUN INDICATES UPWELLING COOLER WATER MAY ALSO BE A CONTRIBUTING 
FACTOR IN THE RECENT WEAKENING TREND. HOWEVER, THERE IS NO EVIDENCE OF 
DRY AIR ENTRAINMENT INTO THE SYSTEM'S CORE AS FORECASTED IN EARLIER 
RUNS. BASED ON THE RECENT WEAKENING TREND, AGENCY FINAL-T ESTIMATES 
RANGING FROM T5.5 TO T6.0 (102-115 KTS), AND ADT, AIDT ESTIMATES, THE 
INITIAL INTENSITY IS ASSESSED AT 115 KNOTS WITH MEDIUM CONFIDENCE. 
DVORAK CURRENT INTENSITY (CI) ESTIMATES (SEE BELOW) ARE HELD 
CONSERVATIVELY HIGHER AND RANGE FROM 115 TO 127 KNOTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WEAK SUBTROPICAL RIDGE (STR) POSITIONED
TO THE WEST, AND A NEAR-EQUATORIAL RIDGE (NER) POSITIONED TO THE SOUTH, 
WHICH WILL LIMIT AND SLOW SOUTHWARD TRACK MOTION. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: CI 6.5 - 127 KTS
   RJTD: CI 6.5 - 127 KTS
   RCTP: CI 6.5 - 127 KTS
   KNES: CI 6.0 - 115 KTS
   CIMSS ADT: 117 KTS AT 270130Z
   CIMSS AIDT: 116 KTS AT 270130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: FRICTIONAL EFFECTS

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: ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE OVERALL 
WITH RADIAL OUTFLOW, LOW VWS, WARM SST (30 C) AND MODERATE OCEAN HEAT 
CONTENT VALUES. FRICTIONAL EFFECTS AND UPWELLING COOLER WATER ARE 
EXPECTED TO OFFSET THE FAVORABLE CONDITIONS AND PRODUCE A MARKED 
WEAKENING TREND OVER THE NEXT 24 HOURS. AFTER TAU 24, TY 09W WILL
STEADILY REINTENSIFY AS IT TRACKS POLEWARD REACHING A SECONDARY
PEAK OF 130 KNOTS BY TAU 72. AFTER TAU 72, A STR IS EXPECTED TO
BUILD TO THE NORTH, WHICH WILL DRIVE THE SYSTEM ONTO A NORTHWESTWARD 
TRACK TOWARD TAIWAN AND SOUTHEAST CHINA. INTERACTION WITH LAND WILL 
LEAD TO STEADY WEAKENING IN THE EXTENDED PORTION OF THE FORECAST.

MODEL DISCUSSION: DUE TO THE COMPLEX, EVOLVING STEERING PATTERN,
THERE IS MEDIUM OVERALL CONFIDENCE IN THE JTWC TRACK FORECAST. THE
261800Z EPS AND GEFS ENSEMBLES ALSO SUPPORT THE JTWC TRACK FORECAST 
WITH MEDIUM CONFIDENCE BUT INDICATE A MODERATE SPREAD IN SOLUTIONS FROM 
CENTRAL TAIWAN TO ABOUT 21N LATITUDE. THE 261200Z COAMPS-TC ENSEMBLE 
SUPPORTS THE SECONDARY REINTENSIFICATION PHASE AND SHOWS INCREASING RI 
PROBABILITIES OF 40 TO 50 PERCENT IN THE TAU 48 TO TAU 72 TIMEFRAME. 

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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