WDPN33 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOMPASU) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.8N 124.9E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 337 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY
LARGE MONSOON DEPRESSION WITH WIDE FORMATIVE RAIN BANDS EXTENDING
ALL THE WAY OUT TO THE FAR EASTERN PHILIPPINE SEA AND AS FAR NORTH
AS OKINAWA. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON THE THE EIR LOOP AND A WELL TIMED 101744Z ATMS 88.2GHZ 
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 HEDGED 
SLIGHTLY HIGHER THAN RJTD DVORAK ESTIMATE ALONG WITH THE ADVANCED 
DVORAK TECHNIQUE. ENVIRONMENTAL ANALYSES INDICATE MARGINALLY 
FAVORABLE CONDITIONS FOR DEVELOPMENT CHARACTERIZED BY VERY WARM SSTS 
IN THE PHILIPPINE SEA AND MODERATE POLEWARD OUTFLOW ALOFT OFFSET BY 
MODERATE (15-20KT) VWS. TS 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: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 33 KTS AT 101840Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 IS EXPECTED TO CONTINUE BUILDING INWARD
AND EXTENDING WESTWARD, THIS WILL THEN DRIVE THE SYSTEM ON A
WESTWARD TRACK THROUGH THE LUZON STRAIT, INTO THE SOUTH CHINA SEA
(SCS). THE RIDGE OVER SOUTHEASTERN CHINA WILL ALSO INFLUENCE THE
SYSTEM, FORCING IT TO MOVE ACROSS HAINAN AND THE GULF OF TONKIN
BEFORE MAKING LANDFALL IN NORTHERN VIETNAM BETWEEN TAU 60 AND 72.
THE MARGINALLY FAVORABLE ENVIRONMENT WILL FUEL GRADUAL
INTENSIFICATION TO A PEAK OF 65KTS IN THE SCS WHERE THE ENVIRONMENT
IS EXPECTED TO BE SLIGHTLY MORE FAVORABLE. 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 68NM FROM TAU 12 THROUGH TAU 60. THERE IS
HIGH CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 60. HOWEVER,
ONCE THE SYSTEM MOVES OVER HAINAN AND INTERACTS WITH THE
MOUNTAINOUS TERRAIN, THE SYSTEM TRACK MAY CHANGE SIGNIFICANTLY, 
INDUCING LOW CONFIDENCE POST TAU 72. CONSEQUENTLY, THERE IS MODERATE
CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 60 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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