WDPN31 PGTW 090300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (MALAKAS) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 7.0N 144.5E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 19 NM SOUTH-SOUTHEAST OF IFALIK MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) TO THE EAST-SOUTHEAST OF A DEEP CONVECTIVE BURST THAT HAS PERSISTED FOR THE PAST 6 HOURS. UPPER-LEVEL CIRRUS CLOUDS ARE SEEN STREAMING OVER THE LLCC FROM THE EAST, DENOTING THE STRONG SOUTHEASTERLY TO EASTERLY VERTICAL SHEAR CURRENTLY IMPACTING THE CYCLONE. THE INITIAL INTENSITY REMAINS 40 KT BASED ON SUBJECTIVE DVORAK ESTIMATES OF T3.0 (45 KT) FROM PGTW AND T2.5 (35 KT) FROM RJTD, AS WELL AS REPRESENTATIVE WIND ESTIMATES FROM A 082043Z SMAP PASS. THE LLCC HAS WOBBLED BACK NORTHWARD DURING THE PAST 6 HOURS AFTER TAKING A WESTWARD JOG DURING THE PRECEDING 6 HOURS. SUCH WOBBLES ARE COMMON WHEN DEEP CONVECTION IS OFFSET FROM THE VORTEX CENTER. INITIAL WIND RADII BASIS: COMBINATION OF SMAP DATA AND PERSISTENCE CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS RCTP: T3.5 - 55 KTS CIMSS SATCON: 42 KTS AT 082210Z CIMSS ADT: 43 KTS AT 082340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: FORECAST DISCUSSION: TROPICAL STORM 02W (MALAKAS) CONTINUES TO BE EMBATTLED BY UPPER-LEVEL SOUTHEASTERLY FLOW THAT MAXIMIZES AT 25 KT AROUND 300 MB, JUST BELOW THE OUTFLOW LAYER, AS ANALYZED BY THE GFS AND ECMWF MODELS. THE RESULTING CONVECTIVE STRUCTURE LACKS ANY SIGNS OF PROGRESS TOWARD AXISYMMETRY, IMPLYING THAT MALAKAS MAY STRUGGLE TO MAKE SIGNIFICANT GAINS IN INTENSITY DURING THE NEAR TERM. HOWEVER, THE 300 MB ENVIRONMENTAL FLOW IS FORECAST TO DECREASE TO 20 KT BY 24 HOURS, AND 15 KT BY 36 HOURS, LEADING TO A DECREASE IN VERTICAL SHEAR THAT SHOULD ALLOW CONVECTION TO WRAP FURTHER AROUND THE CIRCULATION CENTER AND FACILITATE INTENSIFICATION. MALAKAS IS FORECAST TO REACH TYPHOON INTENSITY AFTER 48 HOURS AND CONTINUE INTENSIFYING TO A PEAK OF 90 KT IN 96 HOURS IN AN ENVIRONMENT OF WEAK VERTICAL SHEAR AND WARM SEA SURFACE TEMPERATURES. BEYOND 96 HOURS, THE CYCLONE WILL APPROACH COOLER WATERS AROUND LATITUDE 19N AND POTENTIALLY BEGIN ENTRAINING AN AMBIENT DRY SUBTROPICAL AIR MASS, WHICH SHOULD ARREST THE INTENSIFICATION. THE TRACK FORECAST IS MORE STRAIGHT-FORWARD THAN IN PREVIOUS WARNINGS, WITH MODEL GUIDANCE IN TIGHT AGREEMENT THROUGH 48 HOURS, TAKING MALAKAS NORTHWESTWARD WELL SOUTHWEST OF GUAM, STEERED BY THE DEEP-LAYER SUBTROPICAL RIDGE EAST OF THE MARIANAS. A TURN NORTHWARD AROUND THE WESTERN PERIPHERY OF THIS RIDGE IS EXPECTED AROUND 72 HOURS, AT WHICH POINT MODEL SPREAD INCREASES, ESPECIALLY IN THE ALONG-TRACK DIRECTION. STEERING CURRENTS MAY WEAKEN AS THE MID-LATITUDE JET REMAINS WELL NORTH OF THE CYCLONE AND A SHORTWAVE TROUGH CROSSES KYUSHU AND BEGINS ERODING THE STEERING RIDGE. ADDITIONALLY, TROPICAL DEPRESSION 03W TO THE SOUTHWEST OF MALAKAS COULD INDUCE A TEMPORARY WESTWARD JOG IN THE TRACK OF MALAKAS DURING THE 72-96 HOUR PERIOD AS THE TWO VORTICES INTERACT, DEPENDING ON HOW STRONG 03W BECOMES AND THE EXACT PROXIMITY OF THE TWO CIRCULATIONS. SUCH A JOG, IF ANY, IS EXPECTED TO BE SMALL GIVEN THE MUCH LARGER SIZE OF 02W (MALAKAS). GIVEN THESE FACTORS, CONFIDENCE IN THE TRACK FORECAST AFTER 72 HOURS IS MEDIUM. MODEL DISCUSSION: THE JTWC TRACK FORECAST IS CLOSE TO THE MULTI-MODEL CONSENSUS AND SLIGHTLY FASTER THAN THE PREVIOUS FORECAST. THE JTWC INTENSITY FORECAST IS SLIGHTLY BELOW THE MULTI- MODEL CONSENSUS THROUGH 36 HOURS DUE TO EXPECTED IMPEDIMENTS TO INTENSIFICATION, AND SLIGHTLY ABOVE THE CONSENSUS THEREAFTER. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN