WDPN32 PGTW 140300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (CHANTHU) WARNING 
NR 032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.3N 123.8E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 309 NM SOUTH-SOUTHWEST OF KUNSAN AB, SOUTH
KOREA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 03 KTS
   SIGNIFICANT WAVE HEIGHT: 23 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A WEAKENING
SYSTEM WITH THE MAIN CONVECTION SHEARED NORTHEASTWARD, FULLY
EXPOSING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE MSI LOOP ALSO 
SHOWEDTHE SYSTEM HAS HAD MINIMAL MOVEMENT, A CLEAR INDICATION THAT 
IT HAS BECOME QUASI-STATIONARY (QS). THE INITIAL POSITION IS PLACED 
WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC. THE INITIAL 
INTENSITY IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE MODE OF 
AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE WEAKENED 
STATE OF THE SYSTEM. ANALYSIS INDICATES THE CYCLONE IS LODGED IN A 
COL AREA WITH OVERALL MARGINALLY UNFAVORABLE CONDITIONS 
CHARACTERIZED BY STRONG POLEWARD OUTFLOW AND COOLING SSTS OFFSET BY 
STRONG VWS.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: COL BETWEEN SUBTROPICAL RIDGE (STR) TO
THE WEST AND STR TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.5 - 55 KTS
   CIMSS ADT: 37 KTS AT 132340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TY CHANTHU WILL REMAIN QS OVER THE NEXT TWO
DAYS IN THE COL. AFTERWARD, THE STR TO THE NORTHWEST WILL WEAKEN,
ALLOWING THE SECONDARY STR TO THE SOUTHEAST TO ASSUME STEERING AND 
DRIVE THE SYSTEM NORTHEASTWARD TOWARD THE SEA OF JAPAN (SOJ), CROSS 
NORTHERN HONSHU OVER MISAWA, EXIT INTO THE PACIFIC OCEAN, AND BY TAU 
120 WILL BE EAST OF HOKKAIDO. THE UNFAVORABLE CONDITIONS, 
EXACERBATED BY FURTHER COOLING OF THE SSTS AS THE QS SYSTEM 
GENERATES UPWELLING OF DEEP COLD WATER, WILL PROMOTE STEADY 
WEAKENING DOWN TO 45 KTS BY TAU 36. AFTERWARD, THE NORTHEASTWARD 
TRACK INTO HIGHER VWS AND COLDER SSTS OF THE SOJ WILL FURTHER WEAKEN 
IT TO 40 KTS BY TAU 96. CONCURRENTLY BY TAU 72, TY 19W WILL BEGIN 
EXTRA-TROPICAL TRANSITION AND BY TAU 96 WILL TRANSFORM INTO A GALE-
FORCE COLD-CORE LOW. BY TAU 120, THE SYSTEM WILL BE FULLY EMBEDDED 
IN THE BAROCLINIC FLOW IN THE PACIFIC OCEAN WITH AN EXPANDING WIND 
FIELD.  

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT;
HOWEVER, GIVEN THE UNCERTAINTY IN THE STORM MOTION AND DURATION IN
THE COL AREA, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST
THAT IS LAID CLOSE TO THE MODEL CONSENSUS.  


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