WDPN31 PGTW 230300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.7N 124.4E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 208 NM EAST-NORTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 28 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) TO THE NORTHEAST OF THE PRIMARY BROAD CENTRAL CONVECTION ASSOCIATED WITH TROPICAL STORM 22W (TRAMI). THE CONVECTIVE ACTIVITY REMAINED CONSISTENT OVER THE LAST SIX HOURS, INDICATING LACK OF FURTHER DEVELOPMENT, AS 22W IS GETTING CLOSER TO LUZON. UPPER LEVEL OUTFLOW IS MODERATE, HOWEVER LIMITED PRIMARILY TO THE WESTWARD DIRECTION DUE TO SOUTHWESTWARD VERTICAL WIND SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MULTISPECTRAL IMAGERY. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A COMBINATION OF AUTOMATED AND AGENCY ESTIMATES LISTED BELOW. JTWC INTENSITY IS ESTIMATED ABOVE THE AUTOMATED DVORAK ANALYSIS DUE TO THE LARGE SIZE OF THE SYSTEM NOT BEING COMPLETELY ACCOUNTED FOR IN THE ADT, WHICH DOES NOT ENCOMPASS THE CONVECTIVE BANDING ON THE NORTHERN SIDE OF TS 22W. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH-NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS RCTP: T2.5 - 35 KTS KNES: T3.0 - 45 KTS DEMS: T3.0 - 45 KTS CIMSS SATCON: 42 KTS AT 220730Z CIMSS ADT: 32 KTS AT 230000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL STORM 22W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD FOR THE NEXT 12 HOURS, AFTER WHICH IT IS EXPECTED TO TURN WESTWARD, UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTHEAST, AND MAKE LANDFALL OVER CENTRAL LUZON. TS 22W TRANSIT OVER LAND WILL COINCIDE WITH A TEMPORARY BREAK IN THE RIDGING TO THE NORTH, HOWEVER AS THE SYSTEM RE-EMERGES OVER THE WATERS OF SOUTH CHINA SEA, THE RIDGE WILL REBUILD AND INFLUENCE THE PREDOMINANTLY WESTWARD TRACK OF TRAMI. AS THE SYSTEM COMPLETES THE TRANSIT OVER LUZON, A LEESIDE JUMP SCENARIO IS INDICATED BY SEVERAL NUMERICAL MODELS AS A SOUTHERN KINK IN THE TRACK AROUND TAU 36. AS THE SYSTEM CONTINUES TRANSITING WEST, IT WILL ENCOUNTER FAVORABLE ENVIRONMENT, LEADING TO A PEAK INTENSITY OF 60 KTS AROUND TAU 72, HOWEVER POSITIVE IMPACTS FROM THE HIGH SEA SURFACE TEMPERATURES, HIGH OCEAN HEAT CONTENT AND MODERATE TO LOW VERTICAL WIND SHEAR WILL BE OFFSET BY A NORTHEASTERLY SURGE OF COLDER AND DRY AIR. THEREFORE TS 22W IS FORECAST TO START WEAKENING TOWARDS THE END OF THE FORECAST PERIOD. ANOTHER RIDGE BUILDING OVER SOUTHEAST ASIA WILL BECOME A FACTOR IN A POTENTIAL FOR TS 22W TO MAKE LANDFALL OVER VIETNAM OR REMAIN OVER WATER, TRACKING EITHER NORTH OR SOUTH OF THE 120 TAU POSITION. MODEL DISCUSSION: JTWC FORECAST IS LAID NEAR THE MULTI-MODEL CONSENSUS WHICH IS COMPRISED OF A FAIRLY CLOSE GUIDANCE OF NO BIGGER THAN 70 NM CROSS-TRACK SPREAD THROUGHOUT THE FORECAST PERIOD. THERE IS SOME UNCERTAINTY ASSOCIATED WITH THE AFOREMENTIONED LEESIDE JUMP AND THE LOCATION OF THE RE-EMERGENT LLCC, WITH A COUPLE MODELS, INCLUDING GFS SUGGESTING A MORE SOUTHERN TRACK. FOLLOWING THE LANDFALL OVER NORTHERN PHILIPPINES, ALL NUMERICAL MODEL GUIDANCE SUGGESTS A WESTWARD TRACK THROUGHOUT THE FORECAST PERIOD. ANOTHER UNCERTAINTY CHECKPOINT HOWEVER IS IDENTIFIABLE AT TAU 120 AND BEYOND, WHERE THE TRACK OF TS 22W WILL BE DETERMINED PRIMARILY BY THE DEVELOPMENT AND STRENGTH OF THE RIDGE FORMING OVER SOUTHEAST ASIA. GFS INDICATES A LANDFALL OVER VIETNAM WHILE OTHERS TAKE THE TRACK SOUTH OVER WATER WITH INITIAL SOUTHWARD TURN, AND A POTENTIAL RECURVING SCENARIO TOWARDS THE NORTHEAST (ECMWF, GEFS, NAVGEM, UKMET). FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN