WDPN33 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOMPASU) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.9N 121.6E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 260 NM NORTH OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY
LARGE MONSOON DEPRESSION WITH WIDE FEEDER BANDS REACHING UP TO THE 
EAST CHINA SEA TO THE NORTH AND DOWN TO THE SULU SEA TO THE SOUTH. 
THE CENTRAL CONVECTION HAS DEEPENED. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON A COMPOSITE RADAR LOOP FROM PAGASA
AND TRIANGULATED FROM NEARBY SURFACE WIND OBSERVATIONS. THE INITIAL
INTENSITY OF 55KTS IS BASED WITH MEDIUM CONFIDENCE AND OVERALL
ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS
THE IMPROVED 6-HR CONVECTIVE STRUCTURE. ENVIRONMENTAL ANALYSES
INDICATE MARGINALLY FAVORABLE CONDITIONS FOR DEVELOPMENT
CHARACTERIZED BY WARM SSTS IN THE LUZON STRAIT AND STRONG POLEWARD
OUTFLOW ALOFT OFFSET BY MODERATE VWS AND LAND INTERFERENCE FROM
LUZON AND TAIWAN. THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN 
PERIPHERY OF THE MID-LAYER STR TO THE NORTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE AND NEARBY SURFACE WIND
OBSERVATIONS.


CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 51 KTS AT 111140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 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: TS KOMPASU WILL CONTINUE TO TRACK GENERALLY
WESTWARD UNDER THE STEERING STR INTO THE SOUTH CHINA SEA (SCS) AND
ACROSS SOUTHERN HAINAN AND THE GULF OF TONKIN BEFORE MAKING
LANDFALL JUST BEFORE TAU 72 IN NORTHERN VIETNAM. THE MARGINALLY
FAVORABLE ENVIRONMENT WILL FUEL SLIGHT INTENSIFICATION TO A PEAK OF
60KTS AT TAU 24 IN THE SCS WHERE THE ENVIRONMENT IS EXPECTED TO BE
MORE FAVORABLE WITH LOWER VWS. AFTER TAU 24, INCREASING VWS AND
LAND INTERACTION WITH HAINAN WILL SLOWLY WEAKEN THE SYSTEM DOWN TO
35KTS AT TAU 72. AFTER LANDFALL, FRICTIONAL EFFECTS FROM THE RUGGED
VIETNAMESE TERRAIN WILL RAPIDLY ERODE THE SYSTEM DOWN TO 20KTS
AFTER IT CROSSES CAMBODIA INTO LAOS.   

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN VERY TIGHT AGREEMENT,
LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 72,
THEN MEDIUM CONFIDENCE AFTERWARD. COROLLARY TO THIS, THERE IS
MEDIUM CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 72, THEN LOW
AFTERWARD.

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