WDPN31 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (NOKAEN) WARNING NR 
012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.0N 124.1E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 181 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 01W (NOKAEN) WITH A BROAD AND DISORGANIZED
LOW-LEVEL CIRCULATION CENTER (LLCC). DEEP CONVECTION HAS CONTINUED
TO FLARE ALONG THE TROPICAL STORMS NORTHWESTERN FLANK AND THROUGH
AN EASTWARD EXTENDING CONVECTIVE BAND. THE LLCC HAS REMAINED 
COMPLETELY OBSCURED OVER THE LAST FEW HOURS DUE TO THE AFOREMENTIONED 
PULSING CONVECTION IMMEDIATELY TO THE NORTHWEST. ALOFT, TWO 
SUPPORTIVE UPPER-LEVEL OUTFLOW CHANNELS HAVE PERSISTED, AIDING IN THE 
SYSTEMS STEADY SURFACE INTENSITIES NEAR 50 KTS. THE ENVIRONMENT 
REMAINS MARGINALLY FAVORABLE, WITH LOW TO MODERATE VERTICAL WIND 
SHEAR (VWS) OF 10-15 KTS, WARM SEA SURFACE TEMPERATURES OF 27-28 C, 
AND DUAL-CHANNEL OUTFLOW. IN ADDITION, DRY AIR IS EVIDENT THROUGHOUT 
THE REGION, VOIDING THE SOUTHERN SEMICIRCLE OF ANY CONVECTION. THE 
INITIAL POSITION HAS BEEN PLACED WITH LOW CONFIDENCE, BASED ON 
ANIMATED EIR IMAGERY AND A RECENT 170951Z RCM-2 PASS, INDICATING A 
SUSPECTED BROAD AND DISORGANIZED LLCC. THE INITIAL INTENSITY HAS BEEN 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED RCM-2 
PASS, SUBJECTIVE AGENCY DVORAK ESTIMATES, AND CIMSS OBJECTIVE 
INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) POSITIONED TO
THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 55 KTS AT 171130Z
   CIMSS AIDT: 46 KTS AT 171230Z
   CIMSS D-MINT: 50 KTS AT 170712Z
   CIMSS D-PRINT: 54 KTS AT 171200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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 01W IS FORECASTED TO CONTINUE ROUNDING THE
STR AXIS POSITIONED DIRECTLY TO THE EAST OVER THE NEXT 24 HOURS.
FOLLOWING TAU 24, THE EASTERN STR WILL BEGIN WEAKENING AND
MIGRATING EASTWARD DURING THE SAME TIMEFRAME AN STR POSITIONED OVER
VIETNAM AND CAMBODIA BUILDS EASTWARD ACROSS THE PHILIPPINES. DURING
THIS TRANSITION IN STEERING MECHANISMS, TS 01W IS EXPECTED TO BE
DRIVEN NORTHEASTWARD AND ARC BACK TO THE SOUTH BETWEEN TAU 72 AND
TAU 120 ALONG THE EASTERN PERIPHERY OF THE STR DIRECTLY TO THE
WEST. REGARDING INTENSITY, TS 01W IS FORECASTED TO WEAKEN IN
SURFACE INTENSITIES SLIGHTLY OVER THE NEXT 24 HOURS TO 40 KTS WITH
THE INTRODUCTION OF DRY AIR WRAPPING CYCLONICALLY INTO THE SYSTEMS
EASTERN FLANK AND CORE THROUGH THE SOUTHERN SEMICIRCLE. FOLLOWING TAU 
24, AN INCREASE IN VWS ABOVE 20 KTS AND DRY AIR ENTRAINMENT WILL 
COMPETE AGAINST ROBUST DUAL CHANNEL UPPER-LEVEL OUTFLOW, RESULTING IN
STEADY INTENSITIES UNTIL TAU 96, AND THEN CONTINUE A TERMINAL
WEAKENING TREND INTO TAU 120 TOWARD 35 KTS.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR
AGREEMENT THROUGHOUT THE INITIAL 72 HOURS OF THE FORECAST PERIOD,
AS THE SYSTEM ROUNDS THE STR AXIS TO THE EAST. AS TS 01W BEGINS TO
BE DRIVEN BY THE STR POSITIONED OVER VIETNAM AND CAMBODIA,
NUMERICAL MODEL TRACK GUIDANCE BEGINS TO DIVERGE SIGNIFICANTLY.
THROUGH 72, THE JTWC TRACK FORECAST REMAINS CLOSELY ALIGNED WITH
THE MULTI-MODEL CONSENSUS, LENDING MEDIUM CONFIDENCE TO THE JTWC
FORECAST. FOLLOWING TAU 72, CONFIDENCE IN THE JTWC FORECAST TRACK
BECOMES LOW AS THE ARTIFICIAL INTELLIGENCE (AI) SOLUTIONS 
CHARACTERIZE AN EASTWARD TRACK, WHILE THE MAJORITY OF DETERMINISTIC 
AND PROBABILISTIC GUIDANCE ILLUSTRATES A SOUTHWARD TRACK AT VARYING 
SPEEDS. REGARDING INTENSITY, ALL JTWC INTENSITY CONSENSUS 
MEMBERS SHOW GRADUAL WEAKENING OVER THE NEXT 24 HOURS WITH
FORECASTED STEADY INTENSITIES THEREAFTER, LENDING MEDIUM CONFIDENCE
TO THE JTWC INTENSITY FORECAST. 

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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