WDPN32 PGTW 250300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (EWINIAR) 
WARNING NR 05//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (EWINIAR), LOCATED APPROXIMATELY 285 NM 
SOUTHWEST OF IWO-TO, JAPAN, HAS TRACKED NORTH-NORTHWESTWARD AT 07 
KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED, WITH 
MODERATE CONFIDENCE, ON RECENT SATELLITE FIXES FROM PGTW AND RJTD 
AND A 242057Z SSMIS IMAGE. THE CURRENT INTENSITY OF 40 KNOTS IS 
BASED ON A DVORAK T-NUMBER ESTIMATE OF 2.5 FROM PGTW AND OBJECTIVE 
FIXES FROM CIMSS AND CIRA INDICATING AN INTENSITY OF ABOUT 40 KNOTS.
TS 19W IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A 
SUBTROPICAL STEERING RIDGE TO THE EAST TOWARD THE BASED OF SHORTWAVE 
TROUGH EXTENDING SOUTHWESTWARD FROM THE SEA OF JAPAN ACROSS THE EAST 
CHINA SEA. PERSISTENT EASTERLY VERTICAL WIND SHEAR ASSOCIATED WITH 
THE UPPER-LEVEL OUTFLOW FROM STY 18W CONTINUES TO CONFINE THE 
DEEPEST CONVECTION TO THE EASTERN PERIPHERY OF THE PARTIALLY-EXPOSED 
LOW-LEVEL CIRCULATION CENTER.
3. FORECAST REASONING.
   A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE. 
   B. TS 19W IS FORECAST TO TRACK GENERALLY NORTHEASTWARD OVER 
THE NEXT 24 HOURS UNDER THE CONTINUED STEERING INFLUENCE OF THE 
SUBTROPICAL RIDGE TO THE EAST. THEREAFTER, THE SYSTEM WILL MOVE 
POLEWARD AS IT INTERACTS WITH THE APPROACHING SHORTWAVE TROUGH TO 
THE WEST. SLOW INTENSIFICATION IS EXPECTED OVER THE NEXT 48 HOURS 
DUE TO STRONG OUTFLOW ALOFT, WHICH WILL LIKELY IMPROVE AS THE SYSTEM 
BEGINS TO INTERACT WITH THE APPROACHING TROUGH, AND AN ANTICIPATED 
PERIOD OF DECREASING VERTICAL WIND SHEAR. AS THE APPROACHING TROUGH 
MOVES OVER TS 19W, INCREASING VERTICAL WIND SHEAR AND SUPPRESSED 
OUTFLOW WILL HALT THE INTENSIFICATION TREND. THE AVAILABLE NUMERICAL 
MODEL GUIDANCE IS IN FAIR, BUT IMPROVING, AGREEMENT WITH THE CURRENT 
TRACK FORECAST THROUGH TAU 72.
   C. IN THE EXTENDED PERIOD, TS 19W WILL ROUND THE STEERING RIDGE 
AXIS AND ACCELERATE POLEWARD TOWARD THE MIDLATITUDE WESTERLY FLOW 
PATTERN. DURING THIS TIME, INCREASING VERTICAL WIND SHEAR AND 
PASSAGE OVER COOLER WATER WILL INDUCE STEADY WEAKENING. TS 19W IS 
EXPECTED TO REMAIN EQUATORWARD OF A BAROCLINIC BOUNDARY UNTIL 
FORECAST TAU 120, WHEN EXTRATROPICAL TRANSITION IS EXPECTED TO 
BEGIN. THE CURRENT TRACK FORECAST LIES CLOSE TO THE NUMERICAL MODEL 
CONSENSUS. THERE IS HIGH CONFIDENCE IN THE CURRENT FORECAST TRACK.//
NNNN