WDPN31 PGTW 050300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 050000Z TO 080000Z OCT 2006. A. TROPICAL STORM (TS) 19W (BEBINCA), LOCATED APPROXIMATELY 425 NM WEST OF IWO JIMA, HAS TRACKED NORTH-NORTHEASTWARD OVER THE PAST SIX HOURS. SPEED OF MOVEMENT IS DISTORTED AS THE SYSTEM WAS RELOCATED TO ITS CURRENT POSITION AFTER ANIMATED MULTISPECTRAL SAT- ELLITE IMAGERY AND A 042115Z QUIKSCAT PASS REVEALED A NEW LOCATION FURTHER TO THE NORTH. B. TS 19W IS SITTING IN A WEAK STEERING ENVIRONMENT AND IS SLOW- LY MOVING NORTHEAST, MOSTLY DUE TO SELF STEERING AND INFLUENCE FROM MIDLATITUDE WESTERLIES. A MIDLATITUDE LOW IS FORMING WEAKLY OVER THE KOREAN PENINSULA, BUT THE TROUGH DOES NOT APPEAR TO BE AMPLIFYING. THIS IS HAVING THE EFFECT OF LEAVING THE SYSTEM IN A HIGH VERTICAL WIND SHEAR ENVIORNMENT IN THE TROUGH, BUT NOT ACCELERATING TO THE NORTHEAST LIKE A MORE CLASSIC EXTRATROPICAL TRANSITION. AVAILABLE MODEL GUIDANCE SUGGESTS THAT THE MIDLATITUDE LONG WAVE PATTERN DOES NOT SIGNIFICANTLY CHANGE MERIDIONALLY OVER THE NEXT 72 HOURS. THIS WILL ALLOW THE SYSTEMS LOW LEVEL CIRCULATION CENTER (LLCC) TO CON- TINUE ITS SLOW TRACK TO THE NORTHEAST THROUGHOUT THE FORECAST PERIOD. THE DYNAMIC AIDS ALSO AGREE WITH THIS SCENARIO IN THAT ALL EXCEPT FOR WBAR MOVE TS 19W ERRATICALLY AND SLOWLY THROUGH ALL TAUS. THIS FORECAST IS BASED ON A BLEND OF MODEL GUIDANCE AND SATELLITE AN- ALYSIS OF THE SYNOPTIC ENVIRONMENT. C. UPPER LEVEL ANALYSIS REVEALS THAT THE SYSTEM IS AT LEAST UNDER 40 TO 50 KNOTS OF VERTICAL WIND SHEAR. GIVEN THE SIZE OF THE SYSTEM HOWEVER, ITS POSITION OVER VERY WARM WATER, AND THE EXCELLENT POLE- WARD OUTFLOW, THE SYSTEM IF FORECAST TO SLOWLY WEAKEN THROUGHOUT THE FORECAST PERIOD UNTIL DISSIPATION OVER WATER OCCURS BY TAU 72. D. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR A SYSTEM DIS- SIPATING IN A HIGH SHEAR ENVIRONMENT. FORECAST TEAM: DELTA// NNNN