WDPN31 PGTW 162100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (NOKAEN) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.8N 125.7E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 294 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 01W (NOKAEN) CONTINUING TO CONSOLIDATE, WITH DEEP,
WIDE-SPREAD CONVECTION COMPLETELY OBSCURING THE LOW-LEVEL CIRCULATION 
CENTER (LLCC). THE OVERALL STRUCTURE HAS BECOME SIGNIFICANTLY MORE 
ORGANIZED OVER THE PAST TWELVE HOURS, WITH THE VORTEX BEGINNING TO 
VERTICALLY ALIGN. THE INITIAL POSITION IS PLACED WITH MEDIUM 
CONFIDENCE BASED ON A 161548Z OCEANSAT-3 OSCAT PASS AND VISIBLE 
FEATURES IN THE ANIMATED EIR. THE INITIAL INTENSITY IS ASSESSED AT 45 
KTS WITH HIGH CONFIDENCE, SUPPORTED BY THE AFOREMENTIONED OSCAT PASS, 
AGENCY DVORAK ESTIMATES AND THE IMPROVED CONVECTIVE STRUCTURE. THE 
ENVIRONMENT REMAINS MARGINALLY FAVORABLE, CHARACTERIZED BY STRONG 
POLEWARD OUTFLOW, WARM (28-29 C) SEA SURFACE TEMPERATURES, OFFSET BY 
LOW TO MODERATE (15-20 KTS) EASTERLY VERTICAL WIND SHEAR, WHICH HAS 
ALLOWED FOR THE RECENT INTENSIFICATION.

INITIAL WIND RADII BASIS: A 161548Z OCEANSAT-3 OSCAT PASS

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 38 KTS AT 161740Z
   CIMSS ADT: 51 KTS AT 161730Z
   CIMSS AIDT: 43 KTS AT 161730Z
   CIMSS D-MINT: 43 KTS AT 161654Z
   CIMSS D-PRINT: 48 KTS AT 161830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 01W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYER STR
THROUGH TAU 24. AFTER TAU 24, THE SYSTEM IS EXPECTED TO GRADUALLY
RECURVE TO THE NORTHEAST AS IT ROUNDS THE AXIS OF THE STR. A COMPETING
STEERING RIDGE OVER THE SOUTH CHINA SEA WILL SLOW THE FORWARD
MOTION DURING THIS TURN. BEYOND TAU 72, THE TRAJECTORY BECOMES MORE
EAST-NORTHEASTWARD. AS THE PRIMARY STR WEAKENS AND MOVES EASTWARD
AROUND TAU 96, TS 01W IS EXPECTED TO TURN SOUTHEASTWARD, STEERED BY
THE REMNANT RIDGE. REGARDING INTENSITY, TS 01W IS FORECAST TO REACH
A PEAK INTENSITY AROUND 50 KTS WITHIN THE NEXT 12 HOURS, AS IT TAKES 
ADVANTAGE OF THE CURRENT MARGINALLY FAVORABLE CONDITIONS. AFTER TAU 
24, INCREASING SOUTHERLY VERTICAL WIND SHEAR AND THE ENTRAINMENT OF 
DRIER MID-LEVEL AIR ARE EXPECTED TO INITIATE A SLOW AND STEADY 
WEAKENING TREND THAT WILL PERSIST THROUGH THE REMAINDER OF THE 
FORECAST PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE HAS COME INTO
BETTER AGREEMENT. THE MAJORITY OF MODELS NOW DEPICT A SMOOTH 
RECURVATURE TO THE NORTHEAST, WITH ONLY JGSM SHOWING AN ABRUPT SOUTH-
SOUTHWESTWARD TURN WITHIN 36-48 HOURS. EXCLUDING JGSM, THE CROSS-TRACK
SPREAD AMONG MEMBERS HAS DECREASED TO 40 NM AT TAU 72, INDICATING
INCREASED CONFIDENCE IN THE TRACK FORECAST. THE JTWC TRACK FORECAST
IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS. INTENSITY GUIDANCE IS
IN GOOD AGREEMENT, SHOWING A PEAK BETWEEN TAU 12 AND 24, FOLLOWED
BY SUBSEQUENT WEAKENING. THE JTWC INTENSITY FORECAST IS PLACED NEAR
THE INTENSITY CONSENSUS WITH MEDIUM CONFIDENCE.

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