MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (TWENTY-FOUR) WARNING NR 03// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION 24W (TWENTY-FOUR), LOCATED APPROXIMATELY 520 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST- NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL (MSI) SATELLITE IMAGERY SHOWS DISORGANIZED CONVECTIVE BANDING SLOWLY CONSOLIDATING AROUND AN OBSCURED AND ILL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). DESPITE THE STILL SOMEWHAT DISORGANIZED CONVECTIVE SIGNATURE, A 122232Z SSMIS 91 GHZ MICROWAVE IMAGERY PASS INDICATES THE POSSIBLE MULTIPLE LLCCS FROM THE PREVIOUS DISCUSSION ARE CONSOLIDATING INTO A SINGLE, MORE SYMMETRIC LLCC UNDER THE DENSE OVERCAST. THE INITIAL POSITION IS BASED ON THE CENTROID OF THE BROAD BANDING FEATURES IN THE AFOREMENTIONED MSI AND MICROWAVE IMAGES WITH FAIR CONFIDENCE. THE INITIAL INTENSITY REMAINS AT 30 KNOTS BASED ON THE PGTW DVORAK ESTIMATE OF T2.0 (30 KNOTS). THE SYSTEM RESIDES IN A FAVORABLE ENVIRONMENT, WITH LOW VERTICAL WIND SHEAR, DUAL OUTFLOW CHANNELS, AND VERY WARM SEA SURFACE TEMPERATURES WITH HIGH OCEAN HEAT CONTENT (OHC). A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL CURRENTLY LOCATED TO THE NORTHWEST IS SLIGHTLY ENHANCING POLEWARD OUTFLOW AT THIS TIME, BUT WILL MOVE OUT OF THE AREA OVER THE NEXT 12 HOURS. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) 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 SLOWLY WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGHOUT THE FORECAST PERIOD. AS THE INITIAL POSITION HAS BECOME MORE SOLID, THE TRACK UNCERTAINTY IN THE PREVIOUS FORECAST HAS DECREASED. THROUGH TAU 24, INTENSIFICATION SHOULD OCCUR AT NEAR CLIMATOLOGICAL RATE AS THE LLCC CONTINUES TO ORGANIZE AND THE AFOREMENTIONED TUTT CELL MOVES OUT OF THE AREA. BETWEEN TAUS 24 AND 48, TD 24W IS FORECAST TO SLOW ITS FORWARD MOTION IN RESPONSE TO DEVELOPMENT OF A WEAKNESS IN THE STR FAR TO THE NORTH OVER TAIWAN, IN CONJUNCTION WITH DEVELOPMENT OF A NEAR- EQUATORIAL RIDGE (NER) TO THE SOUTH RESULTING IN A WEAK STEERING ENVIRONMENT. THE STR REESTABLISHES TO THE NORTH AFTER TAU 48 AND TD 24W WILL ACCELERATE TOWARDS LUZON. BY TAU 48, ANOTHER TUTT DEVELOPING TO THE NORTHEAST OF TD 24W WILL MOVE WESTWARD INTO A FAVORABLE POSITION TO PROVIDE INCREASED OUTFLOW, WHICH COMBINED WITH THE VERY FAVORABLE CONDITIONS NOTED, WILL PROVIDE AN ELEVATED POTENTIAL FOR RAPID INTENSIFICATION AFTER TAU 48. FORECAST INTENSITIES PRIOR TO LANDFALL HAVE BEEN ADJUSTED UPWARDS SLIGHTLY TO A PEAK OF 100 KNOTS AT TAU 72 AS A RESULT. HOWEVER, THE ACTUAL PEAK MAY OCCUR AFTER TAU 72, PRIOR TO LANDFALL. C. IN THE EXTENDED TAUS, TD 24W WILL MOVE ACROSS LUZON AND WEAKEN SLIGHTLY DUE TO LAND INTERACTION, BEFORE EXITING INTO THE SOUTH CHINA SEA (SCS). RE-INTENSIFICATION IS EXPECTED IN THE SCS AS GENERALLY FAVORABLE CONDITIONS WILL CONTINUE. NUMERICAL MODEL GUIDANCE BECOMES INCREASINGLY DIVERGENT AFTER TAU 72, WITH SOME MODELS INDICATING A DEVELOPING WEAKNESS IN THE STR CAUSING A MORE NORTHERLY TRACK, WHILE THE MAJORITY OF THE GUIDANCE MAINTAINS THE STR. THE FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS. DUE TO THE VARIABILITY IN THE INITIAL POSITIONING AND THE INCREASING MODEL SPREAD AFTER TAU 72, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN