WDPN32 PGTW 132100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 23W (NAMTHEUN) 
WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.6N 154.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 53 NM SOUTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
CONVECTION OBSCURING A BROAD LOW-LEVEL CIRCULATION (LLC). A 131536Z
AMSR2 89GHZ MICROWAVE IMAGE INDICATES A WEAKLY DEFINED LLC WITH
DISORGANIZED DEEP CONVECTION SHEARED TO THE EAST, LENDING TO MEDIUM
CONFIDENCE IN INITIAL POSITION. TD 23W REMAINS SITUATED UNDER
VIGOROUS UPPER-LEVEL SOUTHERLY FLOW WITH STRONG DIFFLUENCE FUELING
PERSISTENT DEEP CONVECTION OVER THE EASTERN SEMICIRCLE. THE INITIAL
INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON
MULTIPLE AGENCY DVORAK ESTIMATES. ENVIRONMENTAL ANALYSIS REVEALS A
MARGINALLY FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG
NORTHEASTERLY VERTICAL WIND SHEAR OFFSET BY MODERATE RADIAL
OUTFLOW.

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

CURRENT STEERING MECHANISM: NORTHWEST PERIPHERY OF A LOW- TO
MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 41 KTS AT 131504Z
   CIMSS ADT: 33 KTS AT 131740Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 CONTINUE TO TRACK
NORTH-NORTHEASTWARD THROUGH THE FORECAST PERIOD UNDER THE STEERING
INFLUENCE OF THE STR TO THE SOUTHEAST. THE SLIGHT INTENSIFICATION
IS NOW ONLY EXPECTED TO REACH 35 KNOTS VICE 40 KNOTS PREVIOUSLY
ANTICIPATED BY TAU 12, THE SYSTEM WILL STEADILY WEAKEN THROUGH THE
REMAINDER OF THE FORECAST AS CONDITIONS GRADUALLY DEGRADE WITH
DECREASING SSTS AND INCREASING VWS AS IT MOVES INTO THE HIGHER
LATITUDES.   

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT
WITH A 180NM SPREAD IN SOLUTIONS AT TAU 48, LENDING TO MEDIUM
CONFIDENCE TO THE JTWC FORECAST TRACK. INTENSITY GUIDANCE IS IN
FAIR AGREEMENT AS WELL WITH MULTIPLE MODELS SHOWING THE PEAK
INTENSITY AT 35 KNOTS BY TAU 12. THE SYSTEM WILL CONTINUE MOVING
NORTHEAST AND SLOWLY DECREASE INTENSITY AS IT MOVES UNDER THE
INFLUENCE OF THE SUBTROPICAL WESTERLIES AND WILL BEGIN DISSIPATING
OVER THE OPEN WATER STARTING NEAR TAU 36 AND COMPLETE BY TAU 48.   

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM//
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