WDPN32 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (CHAMPI) WARNING NR 
12//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 25W (CHAMPI), LOCATED APPROXIMATELY 73 NM 
EAST-NORTHEAST OF SAIPAN, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) 
CONTINUES TO SHOW DEEPENED CENTRAL CONVECTION OBSCURING THE LOW-
LEVEL CIRCULATION CENTER. THE CURRENT POSITION IS BASED ON THE MSI 
LOOP AND SATELLITE FIXES FROM PGTW AND RJTD WITH FAIR CONFIDENCE. 
THE INITIAL INTENSITY OF 60 KNOTS IS BASED ON THE CURRENT STRUCTURE 
AND OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY ESTIMATES 
(RANGING FROM 55 TO 65 KNOTS) FROM ALL REPORTING AGENCIES. UPPER-
LEVEL ANALYSIS INDICATES TS 25W IS LOCATED IN AN AREA OF LOW TO 
MODERATE (10 TO 20 KNOT) VERTICAL WIND SHEAR THAT BEING OFFSET BY 
THE STRONG DIVERGENT OUTFLOW. TS CHAMPI IS TRACKING UNDER THE 
SOUTHERN PERIPHERY OF A DEEP STR TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE. HOWEVER, TS 25W HAS TRACKED 
MORE WESTWARD OVER THE PAST SIX HOURS, PLACING THE CURRENT POSITION 
SLIGHTLY SOUTH FROM THE PREVIOUS FORECAST TRACK. THEREFORE, THE 
CURRENT TRACK FORECAST HAS BEEN SHIFTED SLIGHTLY TO THE SOUTH TO 
REFLECT THIS STORM MOTION CHANGE. SEE WARNING GRAPHIC FOR CPA 
CHANGES.
   B. TS CHAMPI WILL TRACK ON A WEST-NORTHWESTWARD TRACK OVER THE 
NEXT 36 HOURS UNDER THE INFLUENCE OF THE STR EXTENSION. THE SYSTEM 
WILL BECOME MORE IN-PHASE WITH THE VWS FACTORS ALLOWING FOR GRADUAL 
INTENSIFICATION. ADDITIONALLY, THE STR EXTENSION WILL SLOWLY RETREAT 
TO THE EAST, ALLOWING TS 25W TO BEGIN TO ROUND THE RIDGE AXIS BY TAU 
48. AFTERWARDS, THE SYSTEM WILL TRACK NORTHEASTWARD ALONG THE 
NORTHWESTERN PERIPHERY OF THE STR. CONCURRENTLY, ENHANCED POLEWARD 
OUTFLOW IS EXPECTED, ALLOWING THE SYSTEM TO CONTINUE INTENSIFYING 
LEADING TO A PEAK INTENSITY OF 100 KNOTS BY TAU 48.
   C. IN THE EXTENDED TAUS, TS CHAMPI WILL REMAIN ON A NORTHEASTWARD 
TRAJECTORY. THE SYSTEM IS EXPECTED TO SLOWLY DECAY AS IT TRACKS INTO 
COOLING SSTS AND INCREASING VWS ENVIRONMENT. NUMERICAL MODEL 
GUIDANCE HAS CONTINUED TO SHOW TIGHT AGREEMENT, LENDING HIGH 
CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS POSITIONED CLOSE TO 
MULTI-MODEL CONSENSUS.//
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