WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (TWENTYTHREE) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9N 122.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 135 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION BUILDING OVER A PARTIALLY OBSCURED LOW-LEVEL CIRCULATION
CENTER (LLCC) WHICH IS REPRESENTATIVE OF THE DEVELOPING TREND
TROPICAL DEPRESSION (TD) 23W HAS CONTINUED ON OVER THE LAST SIX
HOURS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
THE AFOREMENTIONED ANIMATED EIR WHICH REVEALED THE LLCC
INTERMITTENTLY BETWEEN CIRCULATING CONVECTIVE BANDS. THE INITIAL
INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE
AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 28 KTS AT 161140Z
   CIMSS AIDT: 30 KTS AT 161140Z
   CIMSS D-MINT: 22 KTS AT 160942Z
   CIMSS D-PRINT: 26 KTS AT 161230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 23W WILL TRACK IN A NORTHWESTWARD DIRECTION
FOR THE NEXT 48 HOURS WHILE UNDER THE STEERING INFLUENCE OF A
SUBTROPICAL RIDGE TO THE NORTHEAST. WHILE ON THIS TRACK, TD 23W
WILL PASS OVER LUZON BETWEEN TAU 0-24 AND INHIBIT INTENSIFICATION.
WHEN THE SYSTEM PASSES BACK OUT OVER WATER AT TAU 36, THE SYSTEM
WILL RESUME INTENSIFICATION TO A PEAK OF 55KTS WHILE IN A FAVORABLE
ENVIRONMENT OF LOW VERTICAL WIND SHEAR, WARM SEA SURFACE
TEMPERATURES, AND STRONG UPPER-LEVEL DIVERGENCE. A NEW SUBTROPICAL
RIDGE APPROACHING FROM THE NORTHWEST WILL BECOME THE PRIMARY
STEERING INFLUENCE BETWEEN TAU 48-72, WHICH WILL RESULT IN A
WESTWARD TRACK FOR THE REMAINDER OF THE FORECAST PERIOD. TD 23W
WILL MAKE LANDFALL IN THE VICINITY OF HONG KONG FOLLOWING TAU 72,
CAUSING THE SYSTEM TO BEGIN DISSIPATING BY THE END OF THE FORECAST
PERIOD.

MODEL DISCUSSION: THERE IS A SIGNIFICANT SPREAD IN THE JTWC
MULTI-MODEL CONSENSUS GUIDANCE WHICH TIES THE VARIABILITY IN THE
MODEL GUIDANCE CLOSELY TO THE INTENSITY GUIDANCE. WHILE THERE IS
NOT A DRASTIC SPREAD SPATIALLY, WITH ONLY A 110NM SPREAD BY THE END
OF THE FORECAST PERIOD, SLIGHT VARIATION IN THE TRACK GUIDANCE
WOULD RESULT IN A LARGE DIFFERENCE IN INTENSITY. HALF OF THE JTWC
CONSENSUS MEMBERS (NAVGEM, ECMWF, ECENS) TRACK OVER LAND NEAR HONG
KONG BETWEEN TAU 72-96. ALTERNATIVELY, THE OTHER CONSENSUS MEMBERS
(GFS, GEFS) LIE TO THE SOUTH AND REMAIN OVER WATER IN THE SOUTH
CHINA SEA, ALLOWING FOR A LONGER PERIOD OF INTENSIFICATION OVER
WATER. CURRENTLY, THE JTWC FORECAST LIES CLOSER TO ECMWF AND ECENS,
BOTH OF WHICH MORE ACCURATELY DEPICT THE CURRENT POSITION OF TD
23W. AS A RESULT, THE INTENSITY FORECAST LIES JUST BELOW THE JTWC
MULTI-MODEL CONSENSUS MEAN.

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