WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (NOKAEN) WARNING NR 
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 13.5N 125.0E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 242 NM EAST-SOUTHEAST OF MANILA,
PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 19 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS TROPICAL
STORM (TS) 01W (NOKAEN) UNDERGOING FURTHER CONSOLIDATION, WITH A
PRONOUNCED CENTRAL DENSE OVERCAST (CDO) OBSCURING THE LOW-LEVEL
CIRCULATION CENTER (LLCC). MULTIPLE FLARE-UPS OF DEEP AND COLD 
CONVECTION CAN BE SEEN THROUGHOUT THE CDO, WITH SOME DRY AIR 
ENTRAINMENT FROM THE SOUTH. THE OVERALL CYCLONIC STRUCTURE HAS 
EXHIBITED SIGNIFICANT ORGANIZATION OVER THE PRECEDING 12 HOURS, WITH 
THE VORTEX ACHIEVING A MORE VERTICALLY STACKED CONFIGURATION. THE 
INITIAL POSITION IS DETERMINED WITH MEDIUM CONFIDENCE, UTILIZING 
EXTRAPOLATION FROM A 162146Z WSFM MWI COLOR 37 GHZ MICROWAVE PASS. THE 
INITIAL INTENSITY IS ASSESSED AT 45 KTS WITH MEDIUM CONFIDENCE, 
CORROBORATED BY THE AGENCY DVORAK ESTIMATES AND OBJECTIVE AIDS LISTED 
BELOW. THE MESOSCALE ENVIRONMENT REMAINS MARGINALLY CONDUCIVE FOR
INTENSIFICATION, CHARACTERIZED BY ROBUST POLEWARD OUTFLOW, WARM
(28-29 C) SEA SURFACE TEMPERATURES, OFFSET BY MODERATE (15-20
KTS) EASTERLY VERTICAL WIND SHEAR (VWS).

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK AND A PARTIAL
162140Z RCM-2 SAR 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: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 57 KTS AT 162030Z
   CIMSS AIDT: 46 KTS AT 162030Z
   CIMSS D-MINT: 42 KTS AT 162148Z
   CIMSS D-PRINT: 57 KTS AT 162310Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   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 PROJECTED TO MAINTAIN A
NORTHWESTWARD TRAJECTORY ALONG THE WESTERN PERIPHERY OF A
DEEP-LAYER SUBTROPICAL RIDGE (STR) THROUGH TAU 24. SUBSEQUENTLY,
THE SYSTEM IS ANTICIPATED TO GRADUALLY RECURVE NORTHEASTWARD AS IT
CROSSES THE STR AXIS. A COMPETING STR OVER THE SOUTH CHINA SEA
WILL INDUCE A MINOR DECELERATION IN FORWARD MOTION DURING THIS
TRANSITION. BEYOND TAU 36, THE TRACK IS EXPECTED TO SWITCH TO A EAST-
NORTHEASTWARD DIRECTION. AS THE PRIMARY STR ATROPHIES AND PROPAGATES
EASTWARD AROUND TAU 96, TS 01W IS FORECAST TO SHIFT TO A
SOUTHEASTWARD HEADING, UNDER THE STEERING INFLUENCE OF THE REMNANT
RIDGE NOW CENTERED TO THE WEST-NORTHWEST. REGARDING INTENSITY, TS
01W IS EXPECTED TO REACH A PEAK INTENSITY OF APPROXIMATELY 50 KTS
WITHIN THE NEXT 12 HOURS, CAPITALIZING ON THE MARGINALLY FAVORABLE 
CONDITIONS. AFTER TAU 24, A SIGNIFICANT INCREASE IN VWS AND THE 
ENTRAINMENT OF DRY MID-LEVEL AIR ARE ANTICIPATED TO INITIATE A GRADUAL 
AND SUSTAINED WEAKENING TREND THROUGHOUT THE REMAINDER OF THE FORECAST 
PERIOD.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE HAS ACHIEVED A HIGHER
DEGREE OF CONSENSUS. ALL MODELS NOW DEPICT A FLUID RECURVATURE TO
THE NORTHEAST, INCLUDING THE PREVIOUS OUTLIER - JGSM. THE
CROSS-TRACK SPREAD AMONG ENSEMBLE MEMBERS IS CURRENTLY AROUND 80 NM
AT TAU 72, BOLSTERING CONFIDENCE IN THE INITIAL TRACK FORECAST, BUT
INDICATING INCREASED UNCERTAINTY SOON AFTER. ALL OF THE AVAILABLE
MODEL GUIDANCE, EXCEPT THE RECENT ECMWF RUN, REFLECT THE PREVIOUSLY
ANALYZED SHIFT IN PRIMARY STEERING MECHANISM WITNESSED BY A
SOUTHWARD TURN TOWARDS THE END OF THE FORECAST PERIOD. THE JTWC
TRACK FORECAST IS POSITIONED IN CLOSE PROXIMITY TO THE MULTI-MODEL
CONSENSUS. INTENSITY GUIDANCE IS IN SUBSTANTIAL AGREEMENT,
INDICATING A PEAK BETWEEN NOW AND TAU 24, FOLLOWED BY SUBSEQUENT
WEAKENING. THE JTWC INTENSITY FORECAST IS PLACED NEAR THE INTENSITY
CONSENSUS WITH MEDIUM CONFIDENCE, DUE TO A RELATIVELY HIGH (25 KTS)
SPREAD OF INTENSITY ESTIMATES BETWEEN TAUS 96 AND 120.

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