WDPN31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING 
NR 10//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 05W (FIVE), LOCATED APPROXIMATELY 123 NM EAST-
NORTHEAST OF DA NANG, VIETNAM, HAS TRACKED NORTHWARD AT 05 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) 
WITH CONVECTION SHEARED TO THE SOUTHWEST. THE INITIAL POSITION IS 
PLACED WITH FAIR CONFIDENCE BASED ON THE EIR LOOP. THE INITIAL 
INTENSITY OF 25 KNOTS IS BASED ON MULTI-AGENCY DVORAK CURRENT 
INTENSITY ESTIMATES OF T1.5 (25 KTS). UPPER LEVEL ANALYSIS REVEALS 
GOOD EQUATORWARD OUTFLOW BUT POOR POLEWARD OUTFLOW. ALTHOUGH THE 
SYSTEM IS TRACKING OVER WARM (30-31 CELSIUS) SEA SURFACE 
TEMPERATURES, INTENSIFICATION IS HAMPERED BY HIGH (25-30 KTS) 
VERTICAL WIND SHEAR (VWS). TD 05W IS CURRENTLY TRACKING NORTHWARD 
ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) LOCATED TO 
THE EAST-NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 05W IS FORECAST TO CONTINUE TRACKING NORTHWARD ALONG THE 
WESTERN PERIPHERY OF THE STR, EVENTUALLY MAKING LANDFALL OVER 
EASTERN HAINAN ISLAND SHORTLY AFTER TAU 24. AFTER TAU 12, DECREASING 
VWS WILL ALLOW TD 05W TO INTENSIFY TO 30 KNOTS PRIOR TO LANDFALL. 
ONCE OVER LAND, TERRAIN INTERACTION WILL PREVENT FURTHER 
INTENSIFICATION AS THE CYCLONE CONTINUES TO TRACK NORTHWARD. 
NUMERICAL MODELS GENERALLY AGREE THE CYCLONE WILL TRACK IN A 
NORTHWARD DIRECTION BUT MOST MEMBERS DEPICT A MEANDERING TRACK AS 
THE CYCLONE SLOWLY MOVES NORTHWARD. HIGH UNCERTAINTY IN THE MODEL 
GUIDANCE LENDS TO LOW CONFIDENCE IN THIS PORTION OF THE JTWC TRACK 
FORECAST. 
   C. AFTER TAU 72, TD 05W IS FORECAST TO CONTINUE TRACKING 
NORTHWARD ALONG THE WESTERN EXTENT OF THE STR AND BRIEFLY PASS OVER 
WATER BEFORE MAKING LANDFALL AGAIN, THIS TIME OVER THE SOUTHERN 
LEIZHOU PENINSULA. THE BRIEF PERIOD BACK OVER WATER WILL BE 
INSUFFICIENT TO ALLOW FOR RE-INTENSIFICATION DESPITE ENVIRONMENTAL 
CONDITIONS BEING OTHERWISE FAVORABLE. TD 05W IS FORECAST TO 
DISSIPATE OVER LAND BY TAU 96. A SLIGHT NORTH-NORTHWESTWARD SHIFT IN 
THE FORECAST TRACK IS DUE TO THE BUILDING STEERING STR. THE OFFICIAL 
FORECAST TRACK CLOSELY FOLLOWS THE MODEL CONSENSUS BUT LARGE SPREAD 
IN THE NUMERICAL MODEL GUIDANCE LENDS ITSELF TO LOW CONFIDENCE IN 
THE JTWC TRACK FORECAST.//
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