WDPN32 PGTW 310900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.9N 132.4E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 420 NM SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH TIGHTLY WRAPPING LOW LEVEL CLOUD LINES. A 310453Z AMSR2 89GHZ MICROWAVE PASS REVEALS THAT 13W IS UNDER RELENTLESS NORTHEASTERLY SHEAR DUE TO THE OUTFLOW FROM 12W WHICH IS 330NM NORTH-NORTHWEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND AMSR2 MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON ADT, SATCON INTENSITY ESTIMATES AND PREVIOUS SCATTEROMETER DATA. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: COMBINATION OF A SUBTROPICAL RIDGE (STR) TO THE EAST AND BINARY INTERACTION WITH STY 12W TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T1.5 - 25 KTS KNES: T1.0 - 25 KTS CIMSS SATCON: 32 KTS AT 310104Z CIMSS ADT: 29 KTS AT 310540Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 20-25 KTS SST: 30-31 CELSIUS OUTFLOW: WEAK EQUATORWARD OTHER FACTORS: NORTHEASTERLY SHEAR FROM STY 12W OUTFLOW. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 13W IS FORECAST TO TRACK GENERALLY NORTH-NORTHWESTWARD ALONG THE EASTERN PERIPHERY OF STY 12W. WHILE THE SYSTEM IS CURRENTLY BEING LIMITED BY THE OUTFLOW FROM 12W WHICH HAS FULLY EXPOSED THE LLCC, THERE IS A NOTABLE OPPORTUNITY FOR DEVELOPMENT AFTER TAU 12. ONCE 13W ESCAPES THIS REPRESSIVE OUTFLOW AND MOVES PARALLEL TO 12W THE OUTFLOW ENVIRONMENT SHOULD IMPROVE DRAMATICALLY, MODEL FIELDS SUGGEST LIMITED EASTWARD AND POLEWARD OUTFLOW FROM STY 12W AND DEVELOPMENT OF AN EQUATORWARD AND EASTWARD OUTFLOW CHANNEL FOR TD 13W. THIS NEW OUTFLOW PATTERN COUPLED WITH THE ALREADY WARM SEA SURFACE TEMPERATURES AND MILD VERTICAL WIND SHEAR SHOULD ALLOW FOR A PERIOD OF INTENSIFICATION TO A PEAK OF APPROXIMATELY 40 KNOTS BY TAU 36. AFTER TAU 36, 13W WILL CONTINUE TO INTERACT WITH STY 12W UNTIL FULLY DISSIPATING AS A SEPARATE AND DISTINCT CIRCULATION CENTER BY TAU 48 WITH AN INTENSITY NEAR 40KTS. FURTHERMORE, THERE IS A SMALL CHANCE FOR A SECONDARY OUTCOME TO THIS STORY. HWRF-P HAS SHOWN CONSISTENT MODEL OUTPUTS THAT INDICATE 13W MAY BE ABLE TO DEVELOP AND MAINTAIN A VERY SMALL, DISTINCT CIRCULATION CENTER, THAT TAPS INTO THE AFOREMENTIONED GOOD DIVERGENT OUTFLOW AND RAPIDLY INTENSIFIES TO TYPHOON STRENGTH BEFORE TAU 48, THEN MAKES A COMPLETE ORBIT OF 12W BEFORE DISSIPATING. MODEL DISCUSSION: WITH THE EXCEPTION OF GALWEM, NUMERICAL MODELS ARE IN GOOD AGREEMENT THAT 13W WILL TRANSLATE ALONG THE EASTERN AND NORTHERN PERIPHERY OF 12W BEFORE FULLY INTEGRATING AND THEREBY DISSIPATING. FOR THIS REASON THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT 13W WILL INITIALLY STRUGGLE TO INTENSIFY AFTER WHICH THE SYSTEM WILL ACHIEVE A PEAK OF 40KTS MAYBE A BIT HIGHER BEFORE ITS INEVITABLE INTEGRATION WITH 12W. NOTWITHSTANDING THE UNLIKELY BUT POSSIBLE HWRF-P PREDICTION MENTIONED ABOVE, BINARY INTERACTIONS ARE NOTORIOUSLY CHALLENGING FOR MODELS TO HANDLE, AND THUS THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN