MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN) WARNING NR 01// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION 27W (TWENTYSEVEN), LOCATED APPROXIMATELY 282 NM NORTH OF CHUUK, HAS TRACKED SOUTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS AN AREA OF FLARING CONVECTION CENTRALLY LOCATED OVER A LOW- LEVEL CIRCULATION CENTER (LLCC). A 191704Z 89GHZ MHS MICROWAVE IMAGE DEPICTS A DEEP CONVECTIVE MASS WITH EVIDENCE OF FORMATIVE BANDING IN BOTH THE NORTHERN AND SOUTHERN SEMI-CIRCLES. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE PGTW SATELLITE FIX AND THE AFOREMENTIONED MICROWAVE IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS BASED ON DVORAK ESTIMATES RANGING FROM T1.0 TO T1.5 (25 KNOTS) FROM KNES AND PGTW RESPECTIVELY. THE INITIAL INTENSITY IS ALSO SUPPORTED BY A 191138Z METOP-B ASCAT IMAGE SHOWING 25 KNOTS IN THE SOUTHWESTERN QUADRANT. ENVIRONMENTAL ANALYSIS REVEALS THAT THE SYSTEM IS IN AN AREA OF LOW (5-10 KNOTS) VERTICAL WIND SHEAR (VWS) AND IS TRACKING THROUGH AN AREA OF WARM (31 CELSIUS) SEA SURFACE TEMPERATURES (SSTS). TD 27W IS LACKING AN ORGANIZED OUTFLOW CHANNEL, HOWEVER, IT IS LOCATED TO THE SOUTHEAST OF A TUTT CELL. THUS THE LIMITED POLEWARD OUTFLOW IS BEING ENHANCED BY THE TUTT CELL. THE SYSTEM HAS BEEN TRACKING TO THE SOUTHEAST AND IS CURRENTLY QUASI-STATIONARY UNDER THE INFLUENCE OF A NEAR EQUATORIAL RIDGE LOCATED TO THE SOUTHWEST AND A BUILDING SUBTROPICAL RIDGE LOCATED TO THE NORTHEAST. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST PHILOSOPHY FOR TROPICAL DEPRESSION 27W. B. TD 27W IS FORECAST TO TRACK NORTHWEST OVER THE NEXT 48 HOURS UNDER THE INFLUENCE OF THE BUILDING SUBTROPICAL RIDGE TO THE NORTHEAST. AFTER TAU 48, THE SYSTEM WILL TRACK MORE NORTH-NORTHWEST AS IT ROUNDS THE RIDGE AXIS. GRADUAL INTENSIFICATION IS FORECAST TO OCCUR THROUGH TAU 24, PEAKING AT 35 KNOTS. AROUND TAU 24, THE ENVIRONMENT WILL BECOME UNFAVORABLE DUE TO INCREASING VERTICAL WIND SHEAR, THE RESULT OF THE SYSTEM?S PROXIMITY TO TY 25W. AFTER TAU 48, THE SYSTEM WILL BEGIN A WEAKENING TREND AS IT INTERACTS WITH TYPHOON 25W, EVENTUALLY BECOMING ABSORBED BY TY 25W BY TAU 96. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT IN THE LATER TAUS FOR THE TRACK DIRECTION, HOWEVER, THE INITIAL PERIOD OF QUASI- STATIONARY MOTION CAUSES A HIGH DEGREE OF UNCERTAINTY, LENDING LOW CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN