WDPN31 PGTW 222100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (PABUK) WARNING NR 
08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 19W (PABUK), LOCATED APPROXIMATELY 104 NM SOUTH-
SOUTHEAST OF IWO TO, HAS TRACKED NORTHWESTWARD AT 05 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS CONVECTION 
AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC) WHICH HAS BEEN 
FLARING OVER THE PAST 24 HOURS, BUT IN THE MOST RECENT FEW HOURS 
CONVECTION WITHIN THE NORTHEASTERN QUADRANT HAS STARTED TO BUILD 
BACK OVER THE CENTER OF THE SYSTEM. THE CURRENT INTENSITY OF 50 
KNOTS IS BASED ON A RECENT 221217Z ASCAT PASS SHOWING A BAND OF 45 
KNOT WINDS WITHIN THE NORTHWEST-NORTHEAST-SOUTHEAST QUADRANTS AND A 
SMALLER BAND OF 50 KNOT WINDS IN THE NORTHEASTERN QUADRANT. DVORAK 
ESTIMATES FROM PGTW AND RJTD ARE SLIGHTLY BELOW THE OBSERVED WINDS 
IN ASCAT, WITH THE ESTIMATE FROM KNES CLOSELY APPROXIMATING THE 
CURRENT INTENSITY. UPPER LEVEL ANALYSIS INDICATES A POINT-SOURCE 
ANTICYCLONE IS ENHANCING RADIAL OUTFLOW. HOWEVER, THIS IS OFFSET BY 
LIGHT TO MODERATE (10-20 KNOT) VERTICAL WIND SHEAR (VWS). TOTAL 
PRECIPITABLE WATER IMAGERY SHOWS A BAND OF DRY AIR PENETRATING 
TOWARDS THE CENTER OF THE SYSTEM ALONG THE WESTERN PERIPHERY. THE 
CYCLONE IS TRACKING ALONG THE OUTER PERIPHERY OF A LOW- TO MID-
LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 19W IS EXPECTED TO TRACK ALONG THE SOUTHWESTERN PERIPHERY 
OF THE STR FOR THE NEXT 36 HOURS UNTIL A MID-LATITUDE TROUGH LOCATED 
OVER NORTHERN CHINA RE-ORIENTS THE STR TO BRING THE SYSTEM TO THE 
NORTHEAST. IMPROVING POLEWARD OUTFLOW AS THE TROUGH APPROACHES WILL 
HELP TO INTENSIFY THE SYSTEM THROUGH TAU 72 AS THE LLCC REMAINS WELL 
DEFINES.
   C. BEYOND TAU 72, TS PABUK IS EXPECTED TO ACCELERATE 
NORTHEASTWARD AND BEGIN EXTRA-TROPICAL TRANSITION AS THE CYCLONE 
GETS EMBEDDED IN THE COLD BAROCLINIC ZONE. TS 19W WILL BECOME A COLD 
CORE LOW BY TAU 120. CONCURRENTLY, INCREASING VWS AND COOLING SEA 
SURFACE TEMPERATURE WILL CAUSE A STEADY DECAY. THE MODEL GUIDANCE - 
EVEN THOUGH ALL MEMBERS INDICATE A NORTHEASTWARD RECURVATURE BEFORE 
ANY IMPACT TO JAPAN - REMAINS WIDELY SPREAD AT THE TURN, HENCE, THE 
CONFIDENCE IN THE FORECAST TRACK REMAINS LOW.//
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