MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING NR 008// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 06W (SIX), LOCATED APPROXIMATELY 681 NM EAST OF KADENA AB, OKINAWA, HAS TRACKED WESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A FULLY-EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION WITH ISOLATED FLARING CONVECTION TO THE SOUTH-SOUTHWEST OF THE CENTER. THEREFORE, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS ASSESSED AT 25 KNOTS BASED ON RECENT ASCAT DATA AS WELL AS DVORAK CURRENT INTENSITY ESTIMATES OF 1.5 (25 KNOTS) FROM PGTW AND RJTD. DESPITE FAVORABLE SST (NEAR 30C), TD 06W CONTINUES TO STRUGGLE DUE TO PERSISTENT, MODERATE (20 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS) AND DRY AIR ENTRAINMENT AS INDICATED IN TOTAL PRECIPITABLE WATER IMAGERY AND LOW 700-500MB RH VALUES OF 40-45%. TD 06W IS TRACKING WESTWARD UNDER THE SOUTHERN PERIPHERY OF THE LOW- LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. DUE TO THE WSW-ENE ORIENTATION OF THE LOW-LEVEL STR, TD 06W IS FORECAST TO GRADUALLY TURN WEST-SOUTHWESTWARD AS IT APPROACHES THE RYUKYU ISLANDS. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN MARGINAL WITH MODERATE EASTERLY VWS AND DRY AIR ENTRAINMENT (700- 500MB RH VALUES OF 45-50%), THEREFORE, THE SYSTEM SHOULD REMAIN SHALLOW AND WEAK WITH SOME POTENTIAL FOR DISSIPATION DURING THE FORECAST PERIOD. NUMERICAL MODEL GUIDANCE SUPPORTS THE JTWC FORECAST TRACK AND REMAINS IN FAIR AGREEMENT WITH MINOR VARIATIONS IN TRACK ORIENTATION. MODEL SPREAD BETWEEN TAU 48 AND TAU 72 RANGES FROM 50- 70NM, THEREFORE, THE JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS WITH MODERATE CONFIDENCE.// NNNN NNNN