WDPN32 PGTW 101500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (NAMTHEUN) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.4N 159.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 420 NM WEST-SOUTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS ENHANCED
AND DEEPENED CENTRAL CONVECTION OBSCURING A PREVIOUSLY PARTIALLY-
EXPOSED LOW LEVEL CIRCULATION (LLC). A WIDE SWATH OF FRAGMENTED 
FORMATIVE BANDING IS WRAPPING IN FROM THE EAST SIDE. THE INITIAL 
POSITION AND INTENSITY OF 40KTS ARE PLACED WITH HIGH CONFIDENCE 
BASED ON A 101101Z ASCAT BULLSEYE PASS AND CONSISTENT WITH THE HIGH 
END OF AGENCY DVORAK ESTIMATES AND IN LINE WITH THE ADT ESTIMATE OF 
39KTS. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR 
DEVELOPMENT WITH ROBUST RADIAL OUTFLOW, LOW TO MODERATE VWS, AND 
WARM SSTS. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF 
AN EASTERN EXTENSION OF THE MID-LAYER OF THE STR TO THE NORTHWEST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: EXTENSION OF THE SUBTROPICAL RIDGE
(STR) TO THE NORTHWEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 39 KTS AT 101130Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS NAMTHEUN WILL CONTINUE ON ITS CURRENT TRACK
UP TO TAU 48. AFTERWARD, A SECONDARY STR TO THE EAST-SOUTHEAST WILL
ASSUME STEERING AND DRIVE THE SYSTEM POLEWARD, CREST THE STR AXIS
NEAR TAU 72, THEN RECURVE IT NORTHEASTWARD. THE FAVORABLE CONDITIONS 
WILL PROMOTE A STEADY INTENSIFICATION TO A PEAK OF 65KTS BY TAU 72. 
AFTERWARD, INCREASING VWS AND COOLING SSTS WILL GRADUALLY DECAY THE 
SYSTEM DOWN TO 40KTS BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH THE
WIDEST SPREAD OF 330+ NM AT TAU 72. EEMN IS THE NOTABLE LEFT
OUTLIER. IN VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC
TRACK UP TO TAU 72 AND MEDIUM CONFIDENCE AFTERWARD. THERE IS MEDIUM
CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 120.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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