MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 217 NM SOUTHEAST OF MAJURO, MARSHALL ISLANDS, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS PERSISTENT CONVECTION OVER AN OBSCURED LOW LEVEL CIRCULATION. A WEAK AND FRAGMENTED FORMATIVE BAND IS ALSO EVIDENT ALONG THE SOUTHERN FLANK. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE EIR LOOP AND LINED UP WITH A SEMI-CLOSED CIRCULATION FEATURE IN THE 041503Z 36GHZ SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 25 KNOTS IS BASED ON THE DVORAK INTENSITY ESTIMATES OF T1.0 AND T1.5 FROM KNES AND PGTW AND IS CONSISTENT WITH THE EIR CONVECTIVE STRUCTURE. THE INITIAL POSITION AND INTENSITY ARE ALSO CONSISTENT WITH NEARBY SURFACE OBSERVATIONS. ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (15 TO 20 KNOT) VERTICAL WIND SHEAR (VWS) OFFSET BY GOOD RADIAL OUTFLOW WITH A STRONG POLEWARD BIAS. SEA SURFACE TEMPERATURES ARE VERY CONDUCIVE AT 28-30 CELSIUS. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH-NORTHEAST. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE AND SETS THE FORECAST PHILOSOPHY FOR THIS SYSTEM. B. TD 01W WILL CONTINUE TRACKING NORTHWESTWARD TOWARD A BREAK IN THE STR. AFTER TAU 48 AND TRACKING OVER MAJURO, A SECONDARY STR TO THE NORTHWEST WILL ASSUME STEERING AND DRIVE THE SYSTEM ON A MORE WEST-NORTHWESTWARD DIRECTION AND, BY TAU 72, WILL JUST HAVE TRACKED OVER KWAJALEIN ATOLL. DECREASING VWS AND IMPROVING POLEWARD OUTFLOW WILL FUEL A SLOW INTENSIFICATION TO 45 KNOTS BY TAU 72. C. AFTER TAU 72, TD 01W WILL CONTINUE ON A WEST-NORTHWESTWARD TRACK TOWARD GUAM UNDER THE SECONDARY STR. THE FAVORABLE ENVIRONMENTAL CONDITIONS WILL PERSIST AND PROMOTE FURTHER INTENSIFICATION, REACHING 55 KNOTS (POSSIBLY HIGHER) BY TAU 120. THE AVAILABLE NUMERICAL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THE TRACK WITH CTCX AS THE NOTABLE OUTLIER ON THE LEFT MARGIN OF THE MODEL ENVELOPE. HOWEVER, DUE TO THE FORMATIVE NATURE OF THE SYSTEM, THERE IS LOW CONFIDENCE IN ALL PORTIONS OF THE FIRST JTWC WARNING TRACK THAT IS LAID JUST RIGHT OF CONSENSUS TO OFFSET THE UNLIKELY CTCX SOLUTION.// NNNN NNNN