WDPN32 PGTW 150300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (CHANTHU) WARNING 
NR 036//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.1N 126.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 257 NM SOUTHWEST OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: EASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS 
REGAINED ITS CENTRAL CONVECTION THAT IS NOW PARTLY OBSCURING THE LOW 
LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON A NOTCH FEATURE IN THE 142218Z SSMIS 91GHZ 
IMAGE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE 
BASED ON OVERALL ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES 
AND IS SUPPORTED BY A 150031Z ASCAT BULLSEYE PASS SHOWING A WIDE 
PATCH OF 35-KT WIND BARBS ALONG THE SOUTHEAST QUADRANT. ANALYSIS 
INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH STRONG POLEWARD 
OUTFLOW AND LOW VWS OFFSET BY COOLING SSTS AND DRY ENTRAINMENT FROM 
THE NORTHWEST PERIPHERY. THE SYSTEM IS CURRENTLY QUASI-STATIONARY IN 
A COL AREA.

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

CURRENT STEERING MECHANISM: COL BETWEEN SUBTROPICAL RIDGE TO THE
NORTHWEST AND STR TO THE SOUTHEAST. 


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.5 - 35 KTS
   CIMSS ADT: 35 KTS AT 142340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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: TS 19W IS EXPECTED TO REMAIN QS IN THE COL UP
TO TAU 12. AFTERWARD, THE STR TO THE NORTHWEST WILL WEAKEN AND
ALLOW THE STR TO THE SOUTHEAST TO ASSUME STEERING AND DRIVE THE
CYCLONE NORTHEASTWARD. THE MARGINALLY FAVORABLE ENVIRONMENT WILL
MAINTAIN ITS CURRENT INTENSITY OF 35KTS UP TO TAU 24. AFTERWARD, AS
THE SYSTEM TRACKS MORE POLEWARD, INCREASING VWS AND COOLING SSTS IN
THE SEA OF JAPAN WILL WEAKEN IT TOWARD DISSIPATION BY TAU 72,
POSSIBLY SOONER.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN GENERALLY GOOD AGREEMENT
WITH EGRR AND EEMN THE NOTABLE OUTLIERS ERRATICALLY DEFLECTING THE
VORTEX TO THE RIGHT OF THE MAIN CLUSTER; HOWEVER, GIVEN THE 
UNCERTAINTY IN THE STORM MOTION IN THE COL, THERE IS LOW CONFIDENCE
IN THE JTWC TRACK FORECAST THAT IS LAID TO THE LEFT OF THE MODEL 
CONSENSUS TO OFFSET EGRR AND EEMN.


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