WDPN31 PGTW 300300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (SAOLA) WARNING NR 
09//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 10W (SAOLA), LOCATED APPROXIMATELY 355 NM 
SOUTH-SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTH-NORTHWESTWARD 
AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL 
SATELLITE IMAGERY AND A 292355Z SSMIS IMAGE DEPICT A WELL-DEFINED 
LOW-LEVEL CIRCULATION CENTER WITH IMPROVED CONVECTIVE BANDING 
WRAPPING TIGHTLY INTO THE CENTER. ANIMATED WATER VAPOR IMAGERY 
DEPICTS RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW ASSOCIATED 
WITH THE TUTT. BASED ON THE IMPROVED ORGANIZATION AND SSMIS IMAGE, 
THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION AND RECENT TRACK 
MOTION. THE INITIAL INTENSITY OF 55 KNOTS IS BASED ON SUBJECTIVE 
DVORAK ESTIMATES OF 55 KNOTS FROM PGTW, KNES AND RJTD AND IS IN 
AGREEMENT WITH OBJECTIVE INTENSITY ESTIMATES, WHICH RANGE FROM 50-55 
KNOTS. TS 10W IS CURRENTLY TRACKING SLOWLY NORTH-NORTHWESTWARD ALONG 
THE WESTERN PERIPHERY OF A WEAK STEERING RIDGE POSITIONED TO THE 
EAST-SOUTHEAST. THE 29/12Z 500MB ANALYSIS INDICATES THAT THE 
SUBTROPICAL RIDGE (STR) REMAINS ENTRENCHED OVER EASTERN CHINA AND 
JAPAN.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING.
   B. TS 10W IS FORECAST TO CONTINUE TRACKING SLOWLY NORTH-
NORTHWESTWARD THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE 
EASTERN STEERING RIDGE. DYNAMIC MODEL GUIDANCE REMAINS IN FAIR 
AGREEMENT. THE PRIMARY DIFFERENCE BETWEEN THE DYNAMIC MODELS IS THE 
DEGREE OF ERRONEOUS INTERACTION WITH TS 11W WITH NOGAPS, GFS, GFDN 
AND JGSM INDICATING A MORE NORTHWARD TRACK (GREATER INTERACTION) AND 
GFDN, UKMO, WBAR AND ECMWF INDICATING A MORE NORTHWESTWARD TRACK 
(LESSER INTERACTION). IN GENERAL, THE JTWC FORECAST HAS SHIFTED 
SLIGHTLY POLEWARD WITH THE BULK OF THE MODELS ALSO TRENDING POLEWARD 
BUT CONTINUES TO FAVOR ECMWF, WHICH HAS BEEN THE MOST CONSISTENT, 
REALISTIC SOLUTION. THE JTWC FORECAST TRACK IS POSITIONED CLOSE TO 
THE MODEL CONSENSUS AND FAVORS A SLOW, COMPLEX TRACK THROUGH TAU 72 
WITH WEAK INTERACTION WITH TS 11W BETWEEN TAU 48 AND TAU 72. AT THIS 
TIME, THE TWO SYSTEM CENTERS WILL APPROACH WITHIN 400 NM POSSIBLY 
PRODUCING A SHORT-TERM SLOW-DOWN OR ERRATIC TRACK EAST OF TAIWAN; 
HOWEVER, IT IS UNLIKELY THAT 10W WILL BE AFFECTED SIGNIFICANTLY BY 
THE MUCH WEAKER 11W. TS 10W IS EXPECTED TO INTENSIFY TO A PEAK 
INTENSITY OF 100 KNOTS BY TAU 72 DUE TO THE FAVORABLE ENVIRONMENT.
   C. IN THE EXTENDED TAUS, TS 10W WILL TURN WESTWARD JUST TO THE 
NORTH OF TAIWAN AS IT TRANSITIONS TO THE STEERING INFLUENCE OF THE 
STR OVER EASTERN CHINA AND JAPAN. TS 10W AND TS 11W ARE EXPECTED TO 
APPROACH WITHIN 300NM DURING THIS PERIOD BUT 10W AS THE LARGER, MORE 
POWERFUL SYSTEM, AGAIN, SHOULD SEE MINIMAL INFLUENCES. TS 11W, 
HOWEVER, IS EXPECTED TO WEAKEN RAPIDLY AS IT ENCOUNTERS INCREASING 
VERTICAL WIND SHEAR ASSOCIATED WITH 10W'S OUTFLOW AND WILL BE 
ABSORBED INTO 10W BY TAU 96. THERE IS LOW OVERALL CONFIDENCE IN THE 
FORECAST TRACK DUE TO THE WEAK STEERING ENVIRONMENT THROUGH TAU 72 
AND POSSIBLE WEAK INTERACTION WITH 11W. AFTER TAU 72, THERE IS 
INCREASED CONFIDENCE IN THE FORECAST TRACK AS THE STEERING INFLUENCE 
TRANSITIONS TO THE STRONG STR POSITIONED OVER CHINA AND JAPAN.//
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