WDPN33 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOMPASU) WARNING 
NR 004//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.5N 124.2E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 298 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP
CONVECTION WRAPPING ON THE WESTERN AND SOUTHERN SIDE OF AN OBSCURED
LOW LEVEL CIRCULATION CENTER (LLCC). THE SYSTEM REMAINS IN A LARGE
MONSOON DEPRESSION WITH WIDE FORMATIVE RAIN BANDS EXTENDING ALL THE
WAY OUT TO THE FAR EASTERN PHILIPPINE SEA. THE INITIAL POSITION IS
PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI LOOP AND A TIMELY
102300Z GMI 89GHZ IMAGE. THE INITIAL INTENSITY OF 45KTS IS BASED
WITH MEDIUM CONFIDENCE ON MULTIPLE AGENCY FIXES FROM PGTW, RCTP,
KNES DVORAK ESTIMATES AND THE OVERALL STRUCTURE OF THE SYSTEM, AND
REMAINS HIGHER THAN RJTD DVORAK ESTIMATE AND THE ADVANCED DVORAK
TECHNIQUE (ADT). ENVIRONMENTAL ANALYSES INDICATE MARGINALLY
FAVORABLE CONDITIONS FOR DEVELOPMENT CHARACTERIZED BY VERY WARM
SSTS IN THE PHILIPPINE SEA, AND MODERATE EASTERLY OUTFLOW ALOFT 
OFFSET BY MODERATE (15-20KT) VWS. TD 24W IS TRACKING ALONG THE 
SOUTHWESTERN PERIPHERY OF THE STR TO THE NORTHEAST.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

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: 37 KTS AT 102340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EASTWARD

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: THE STR WILL BUILD AND EXTEND FROM WESTWARD,
THIS WILL CONTINUE DRIVING THE SYSTEM WESTWARD THROUGH THE LUZON
STRAIT AND INTO THE SOUTH CHINA SEA (SCS). THE RIDGE OVER
SOUTHEASTERN CHINA WILL ALSO INFLUENCE THE SYSTEM, FORCING THE
MOVEMENT ACROSS HAINAN AND THE GULF OF TONKIN BEFORE MAKING
LANDFALL IN NORTHERN VIETNAM BETWEEN TAU 48 AND 60. THE ENVIRONMENT
IS MORE FAVORABLE IN THE SCS AND TS 24W IS EXPECTED TO REACH A PEAK
INTENSITY OF 70KTS NEAR TAU 48. AFTERWARD, INCREASING VWS AND
INTERACTION WITH HAINAN ISLAND WILL WEAKEN THE SYSTEM DOWN TO 60KTS
AT TAU 72. AFTER LANDFALL, INTERACTION WITH THE RUGGED VIETNAMESE
TERRAIN WILL RAPIDLY ERODE THE SYSTEM DOWN TO 20KTS AFTER IT
CROSSES INTO LAOS NEAR CAMBODIA.

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN TIGHT AGREEMENT WITH
ONLY A MAXIMUM SPREAD OF 50NM FROM TAU 12 THROUGH TAU 48 AND
GRADUALLY SPREADS TO 100NM BY TAU 72 AFTER IT MOVES OVER HAINAN.
THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 48.
HOWEVER, ONCE THE SYSTEM MOVES OVER HAINAN AND INTERACTS WITH THE
MOUNTAINOUS TERRAIN, THE SYSTEM TRACK MAY CHANGE SIGNIFICANTLY AND
INDUCES LOW CONFIDENCE POST TAU 60. CONSEQUENTLY, THERE IS MODERATE
CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 48 AND LOW
CONFIDENCE THEREAFTER. 

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