WDPN31 PGTW 040300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING 
NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 05W (FIVE), LOCATED APPROXIMATELY 121 NM EAST
OF DA NANG, VIETNAM, HAS TRACKED NORTHWARD AT 05 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED MULTI-SPECTRAL SATELLITE IMAGERY 
(MSI) DEPICTS A PARTIALLY EXPOSED, CONSOLIDATING LOW LEVEL 
CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION SHEARED TO THE 
SOUTHWEST. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED 
ON THE MSI LOOP SHOWING THE PARTIALLY EXPOSED LLCC. THE INITIAL 
POSITION WAS ALSO SUPPORTED BY EXTRAPOLATION FROM A 031807Z AMSR2 
36GHZ MICROWAVE IMAGE THAT SHOWS LOW LEVEL BANDING WRAPPING INTO A 
SLIGHTLY ELONGATED LLCC. THE INITIAL INTENSITY OF 25 KNOTS IS BASED 
ON DVORAK CURRENT INTENSITY ESTIMATES OF T1.5 (25 KTS) FROM BOTH 
PGTW AND RJTD. UPPER LEVEL ANALYSIS REVEALS THAT TD 05W HAS GOOD 
DIVERGENCE ALOFT WITH STRONG EQUATORWARD OUTFLOW. ENVIRONMENTAL 
ANALYSIS REVEALS THAT THE SYSTEM IS TRACKING THROUGH WARM (30-31 
CELSIUS) SEA SURFACE TEMPERATURES. THE GOOD OUTFLOW AND WARM SEA 
SURFACE TEMPERATURES ARE OFFSET BY HIGH (25-30 KTS) VERTICAL WIND 
SHEAR (VWS). TD 05W IS CURRENTLY TRACKING NORTHWARD ALONG THE 
WESTERN EXTENT 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 INITIAL LANDFALL 
OVER EASTERN HAINAN ISLAND SHORTLY AFTER TAU 36. THE SYSTEM WILL 
REMAIN IN A MARGINALLY FAVORABLE ENVIRONMENT THROUGH TAU 12 AT WHICH 
TIME, DECREASING VWS WILL ALLOW FOR A BRIEF PERIOD OF 
INTENSIFICATION. THE PERIOD OF INTENSIFICATION WILL ALLOW TD 05W TO 
STRENGTHEN TO 35 KNOTS INTENSITY PRIOR TO LANDFALL. ONCE OVER LAND, 
THE FRICTIONAL EFFECTS OF TERRAIN INTERACTION WILL BEGIN TO 
GRADUALLY WEAKEN THE SYSTEM. AVAILABLE NUMERICAL MODEL GUIDANCE IS 
IN GOOD AGREEMENT THAT THE SYSTEM WILL TRACK NORTHWARD THROUGH TAU 
72. HOWEVER, INDIVIDUAL CONSENSUS MEMBERS SPREAD SIGNIFICANTLY AFTER 
TAU 24 CAUSING A HIGH DEGREE OF UNCERTAINTY AND LENDING OVERALL LOW 
CONFIDENCE TO 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. SHORTLY AFTER TAU 72, 
THE SYSTEM WILL EXIT INTO THE SOUTH CHINA SEA. TD 05W WILL ONLY 
TRACK OVER WATER FOR A SHORT TIME WHICH WILL PREVENT ANY ADDITIONAL 
INTENSIFICATION, MAKING A SECOND LANDFALL OVER SOUTHERN LEIZHOU 
PENINSULA. BY TAU 96, THE SYSTEM WILL SHIFT TRACK DIRECTION TO THE 
NORTH-NORTHWEST AS THE STR BEGINS TO BUILD IN. THE
PERSISTENT LAND INTERACTION AFTER TAU 72 WILL GRADUALLY ERODE THE 
SYSTEM, LEADING TO COMPLETE DISSIPATION OVER LAND BY TAU 120. 
AVAILABLE NUMERICAL MODEL GUIDANCE SPREADS SIGNIFICANTLY AFTER TAU 
72 RESULTING IN LARGE VARITAIONS BY TAU 120. THE 
FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS AND BIASED 
TOWARDS THE ECMWF SOLUTION. HOWEVER, DUE TO THE LARGE SPREAD IN 
MODEL GUIDANCE, THERE IS OVERALL LOW CONFIDENCE 
IN THE JTWC TRACK FORECAST.//
NNNN