MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 521 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS PERSISTENT, DEEP CONVECTION OBSCURING A LOW LEVEL CIRCULATION CENTER (LLCC) SLIGHTLY OFFSET TO THE NORTHEAST OF THE SEMICIRCLE. CONVECTION HAS INCREASED OVER THE PAST 6 HOURS WITH OVERSHOOTING TOPS DEVELOPING IN THE CONSOLIDATING CONVECTIVE ENVELOPE. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON PARTIALLY EXPOSED LOW LEVEL BANDS WRAPPING INTO THE OBSCURED LLCC IN THE MSI LOOP, AS WELL AS EXTRAPOLATION FROM A LOW LEVEL CIRCULATION APPARENT IN 112330Z ASCAT-A DATA TO THE CENTER OF LOW LEVEL FEATURES IN A 120456Z AMSR2 89GHZ IMAGE. THE INITIAL INTENSITY OF 30 KNOTS IS ASSESSED WITH FAIR CONFIDENCE BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T2.0 (PGTW 30 KTS) AND T1.5 (RJTD 30 KTS) AND IS IN LINE WITH THE PERSISTENT CONVECTION PRESENT IN MSI. TD 01W LIES IN AN ENVIRONMENT FAVORABLE FOR FURTHER INTENSIFICATION WITH LOW (5-10 KTS) VWS, GOOD EQUATORWARD AND MODEST POLEWARD OUTFLOW AND WARM (28-29C) SEA SURFACE TEMPERATURES (SSTS). THE SYSTEM IS TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) CENTERED OVER THE NORTHERN MARIANA ISLANDS THAT CONTINUES TO BUILD WESTWARD. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE LAST PROGNOSTIC REASONING MESSAGE. B. OVER THE NEXT 12 HOURS TD 01W WILL TRACK GENERALLY NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF A DEEP NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED STR CENTERED NORTH OF GUAM. THIS STR IS CURRENTLY BUILDING FARTHER WESTWARD TOWARDS NORTHERN LUZON AND WILL RESULT IN SUBSEQUENT STEERING OF TD 01W IN A GENERAL WESTWARD DIRECTION FROM TAU 24 UNTIL LANDFALL NEAR SAMAR ISLAND AT TAU 48. THE ENVIRONMENT OVER THE NEXT 48 HOURS IS EXPECTED TO REMAIN FAVORABLE FOR FURTHER DEVELOPMENT AS THE SYSTEM TRAVELS OVER WATER. AN UPPER LEVEL POINT SOURCE SITUATED ABOVE THE LLCC WILL CONTINUE TO PROVIDE STRONG OUTFLOW, WHILE SEA SURFACE TEMPERATURES ARE TO REMAIN HIGH (28-29C) AND VWS IS TO REMAIN LOW (5-10 KTS) ALLOWING FOR FURTHER INTENSIFICATION. THE PEAK I INTENSITY OF 70 KTS IS FORECAST TO OCCUR AT TAU 48 WHEREUPON THE S SYSTEM WILL STRUGGLE TO FURTHER INTENSIFY AS IT MAKES LANDFALL AT S SAMAR ISLAND DUE TO THE FRICTIONAL EFFECTS OF LAND. AFTER REACHING L LANDFALL AT TAU 48, TD 01W IS FORECAST TO BEGIN TRACKING WEST-NORTHWESTWARD THROUGH TAU 72. NUMERICAL MODEL SOLUTIONS HAVE C COME INTO IMPROVING AGREEMENT THROUGH TAU 72 (128 NM SPREAD AT TAU 4 48, 145NM SPREAD AT TAU 72) LENDING FAIR CONFIDENCE TO THIS PORTION O OF THE JTWC FORECAST TRACK. C. AFTER TAU 72 TD 01W WILL BEGIN A NORTHWESTWARD TRACK UNTIL TAU 96 AS IT TRAVELS INLAND. THE FRICTIONAL EFFECTS OF LAND INTERACTION WILL HINDER FURTHER DEVELOPMENT AND LEAD TO SLIGTH WEAKENING OF THE SYSTEM, HOWEVER THIS WEAKENING WILL BE OFFSET BY CONTINUED ROBUST POLEWARD OUTFLOW AND LOW VWS (5-10 KTS). OUTFLOW FROM A TROPICAL UPPER-TROPOSPHERIC TROUGH (TUTT) CELL POSITIONED OVER THE SOUTH CHINA SEA WILL IMPINGE UPON THE OUTFLOW OF THE SYSTEM AS IT MOVES INLAND HOWEVER THIS CELL IS FORECAST TO TRAVEL SOUTHWARD AND CEASE INTERACTION WITH TD 01W BY TAU 72, AT WHICH POINT IT WILL HAVE WEAKENED TO 65 KTS. BY TAU 96, THE SYSTEM WILL WEAKEN TO 50 KTS AS IT BEGINS TO ROUND THE AXIS OF THE STR POSITIONED TO THE EAST AND TRACK NORTH-NORTHEASTWARD. IT WILL RETAIN ITS INTENSITY OF 50 KTS DURING THIS TIME DUE TO PERSISTENTLY LOW (5-10 KTS) VWS AND ROBUST POLEWARD OUTFLOW. TD 01W WILL CONTINUE TO TRACK NORTH-NORTHEASTWARD AFTER THIS TIME AND REACH THE WARM WATERS OF THE PHILIPPINE SEA NORTH OF APARRI BY TAU 120. THE SPREAD IN MODEL SOLUTIONS INCREASES TO 145 NM BY TAU 72 AND THEN SIGNIFICANTLY INCREASES TO 270 NM BY TAU 96. THE UNCERTAINTY IN MODEL SOLUTIONS IS DUE TO THE TIMING OF THE BUILDING AND REORIENTATION OF THE STEERING RIDGE WITH EACH OF THE GLOBAL MODELS PROVIDING A DIFFERENT CENTER POSITION OF THE RIDGE AT TAU 96-120. THIS INCREASING SPREAD IN MODEL SOLUTIONS AFTER TAU 72 LENDS OVERALL LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN