WDPN31 PGTW 191500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (DUJUAN) WARNING 
NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 01W (DUJUAN), LOCATED APPROXIMATELY 745 NM 
SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-SOUTHWESTWARD AT 
08 KNOTS OVER THE PAST SIX HOURS. CIRRUS BLOW OFF FROM WEAK 
CONVECTION DISSIPATED SUBSEQUENT TO THE 191200Z HOUR, ALLOWING FOR A 
DISTINCT LOW LEVEL CIRCULATION CENTER (LLCC) TO REVEAL ITSELF IN 
ANIMATED ENHANCED 3.9 MICRON SATELLITE IMAGERY TO BE SIGNIFICANTLY 
FURTHER TO THE SOUTH AND EAST OF THE ORIGINAL BEST TRACK POSITION 
AND AGENCY FIX POSITIONS WOULD SUGGEST, RESULTING IN A RELOCATION OF 
THE INITIAL POSITION. LATE RECEIPT OF A 191259Z ASCAT-B 
SCATTEROMETER PARTIAL PASS CONFIRMS THE INITIAL POSITION WITH HIGH 
CONFIDENCE. THE CONVECTIVE MASS THAT WAS ORIGINALLY THOUGHT TO BE 
ASSOCIATED WITH THE LLCC IS NOW REVEALED TO BE DISPLACED WELL TO THE 
NORTHWEST DUE TO THE STRONG EAST-SOUTHEASTERLY VWS.  
THE INITIAL INTENSITY REMAINS SET AT 45 KNOTS WITH LOW CONFIDENCE, 
IN LINE WITH AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T3.0 (45 
KTS) FROM PGTW AND KNES, AND AN ADT ESTIMATE OF T2.9. THE PARTIAL 
ASCAT-B PASS MENTIONED EARLIER SHOWS A MAXIMUM OF 35-40 KNOTS IN THE 
SOUTHWEST QUADRANT BUT THERE COULD BE SLIGHTLY HIGHER WINDS CLOSER 
TO THE CONVECTION TO THE WEST. ENVIRONMENTAL AND SATELLITE ANALYSIS 
SHOWS THAT THE STRONG (20-25 KT) EASTERLY VWS HAS TAKEN ITS TOLL AND 
THE UPPER AND LOWER-LEVELS OF THE SYSTEM HAVE NOW DECOUPLED. WHILE 
POLEWARD OUTFLOW REMAINS ROBUST AND SSTS REMAIN WARM, THE VWS IS 
JUST TOO STRONG TO OFFSET. TS 01W IS TRACKING ALONG THE SOUTHWEST 
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO 
THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING MESSAGE. HOWEVER, THE INITIAL 
POSITION AND PREVIOUS POSITIONS AFTER 181800Z HAVE BEEN 
SIGNIFICANTLY ADJUSTED.
   B. TS 01W IS MOVING SLOWLY WESTWARD, COCOONED IN A WEAKNESS IN 
THE LOW TO MID-LEVEL STR, BEING PUSHED WEST AS THE STR CENTERED TO 
THE EAST HAS EXTENDED AND MOVED WESTWARD. THE SYSTEM IS FORECAST TO 
START MOVING ON A MORE NORTHWESTWARD TRACK BY TAU 12 AS IT RIDES UP 
THE WEST SIDE OF THE STR CENTERED TO THE EAST WHICH TAKES ON A MORE 
NORTHWEST-SOUTHEAST ORIENTATION.  TS 01W IS FORECASTED TO MAKE 
LANDFALL ALONG THE EXTREME NORTHEAST COAST OF MINDANAO NEAR BETWEEN 
TAU 36 AND TAU 48, THEN TRACK OVER THE CENTRAL PHILIPPINE ISLANDS 
AND LYING ALONG THE SOUTH COAST OF MINDORO BY TAU 72. THE SYSTEM IS 
NOT EXPECTED TO UNDERGO ANY ADDITIONAL INTENSIFICATION AND WILL 
STEADILY WEAKEN THROUGH TAU 72 DUE TO THE PERSISTENT EASTERLY VWS, 
AND TERRAIN INTERACTION. EVEN AFTER THE RELOCATION, NUMERICAL MODEL 
GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH 195NM SPREAD AT TAU 48, 
INCREASING TO 235NM AT TAU 72. HOWEVER, IN LIGHT OF THE SIGNIFICANT 
CHANGES IN THE RECENT POSITION AND TRACK, THERE IS LOW CONFIDENCE IN 
THE JTWC FORECAST TRACK THROUGH TAU 72.  
   C. AFTER TAU 72, AS THE SYSTEM CONTINUES TO WEAKEN, IT WILL COME 
UNDER THE STEERING INFLUENCE OF THE LOWER LEVEL NORTHEASTERLY FLOW, 
AND THE TRACK WILL FLATTEN OUT TO A MORE WESTERLY TRACK AFTER TAU 
96. ONCE THE SYSTEM EMERGES INTO THE SOUTH CHINA SEA, IT WILL 
ENCOUNTER A MUCH COOLER AND DRIER AIR MASS, AND CONVERGENT UPPER-
LEVEL FLOW WHICH WILL LEAD TO DISSIPATION BY TAU 120. NUMERICAL 
MODEL GUIDANCE HAS COME INTO BETTER OVERALL AGREEMENT IN THE 
EXTENDED TAUS, WITH ALL CONSENSUS MEMBERS EXCEPT THE UKMET AND ITS 
ENSEMBLE MEAN, CONVERGING ON SOLUTION WHICH TAKES THE SYSTEM INTO 
THE CENTRAL SOUTH CHINA SEA BY TAU 120. SPREAD ACTUALLY DECREASES TO 
195NM BY TAU 120. THE JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE 
MULTI-MODEL CONSENSUS AND CLOSELY TRACKS THE ECMWF SOLUTION, WITH 
FAIR CONFIDENCE.//
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