WDPN31 PGTW 082100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (ETAU) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 24W (ETAU), LOCATED APPROXIMATELY 440 NM 
EAST-SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 20 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH CONVECTIVE BANDING OVER 
THE WESTERN SEMICIRCLE AND A SYMMETRIC DEEP CONVECTIVE BURST 
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 081746Z ATMS 
88.2GHZ MICROWAVE IMAGE ALSO REVEALS IMPROVED CONVECTIVE STRUCTURE 
WITH LIMITED BANDING WRAPPING OVER THE NORTHERN QUADRANT OF A WEAKLY-
DEFINED LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH FAIR 
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 30 KTS BASED ON 
PGTW/RJTD DVORAK INTENSITY ESTIMATES OF T2.0 (30 KNOTS). UPPER-LEVEL 
ANALYSIS INDICATES A GENERALLY FAVORABLE ENVIRONMENT WITH LOW (10-15 
KNOTS) EASTERLY VERTICAL WIND SHEAR AND ENHANCED POLEWARD OUTFLOW. 
SST VALUES REMAIN CONDUCIVE AT 27-28C. TD 24W IS TRACKING ALONG THE 
SOUTHERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) 
ENTRENCHED TO THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TD 24W IS EXPECTED TO TRACK QUICKLY WESTWARD UNDER THE 
STEERING INFLUENCE OF THE AFOREMENTIONED STR THROUGH THE FORECAST 
PERIOD, MAKING LANDFALL OVER EASTERN VIETNAM NEAR TAU 30. AFTER TAU 
30, THE SYSTEM WILL TRACK INLAND AND DISSIPATE OVER MOUNTAINOUS 
TERRAIN BY TAU 48. WITH THE EXCEPTION OF JGSM, NUMERICAL MODEL 
GUIDANCE IS IN TIGHT AGREEMENT WITH A SPREAD OF 33NM AT LANDFALL 
LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. THE 08/1200Z 
ECMWF ENSEMBLE INDICATES GREATER SPREAD AND UNCERTAINTY AT LANDFALL 
WITH A 90NM SPREAD IN SOLUTIONS (LANDFALL CENTER LOCATION FROM 12.5N 
TO 14.0N).//
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