Western North Pacific: still active with Invests 94W rotating around 94W ! 09/03utc updates

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 22W CONTINUES TO TRACK SLOWLY WEST-NORTHWESTWARD OVER HAINAN, EXITING WITHIN THE NEXT FEW HOURS INTO THE GULF OF TONKIN. OVER THE NEXT 12 HOURS, LIONROCK WILL MOVE BACK OVER THE WARM WATERS AND THE UPPER LEVEL OUTFLOW WILL ENHANCE THE INTENSITY GRADUALLY TO 40 KNOTS. TS 22W IS EXPECTED TO CONTINUE MOVING ON A WEST-NORTHWESTWARD TRACK AND THEN TURN SLIGHTLY MORE TO THE WEST-SOUTHWEST JUST BEFORE MAKING LANDFALL JUST SOUTHEAST OF HANOI, VIETNAM. ONCE THE SYSTEM MAKES LANDFALL IT WILL RAPIDLY DECREASE INTENSITY AS IT INTERACTS WITH THE RUGGED TERRAIN AND BEGIN THE DISSIPATION PROCESS STARTING AT 36H AND DISSIPATE NEAR THE FAR WESTERN BORDER OF VIETNAM AND LAOS BY 48H.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATED LOW-LEVEL CIRCULATION (LLC) WITH CONVECTIVE BANDING WEST OF THE LLC. A 090041Z GMI 89GHZ IMAGE INDICATES MOST OF THE CONVECTIVE STRUCTURE MOVED TO THE NORTHWEST OVER THE GULF OF TONKIN WHILE THE LLC REMAINS POSITIONED OVER NORTHWEST HAINAN ISLAND. SURFACE OBSERVATIONS ON HAINAN ISLAND ARE VERY WEAK WITH A MINIMUM SLP OF 994MB NEAR AT HAIKOU, HAINAN. OVERALL, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION BASED ON THE MSI AND RADAR IMAGERY. THERE IS MODERATE CONFIDENCE IN THE INITIAL INTENSITY BASED ON RJTD AND RCTP DVORAK INTENSITY ESTIMATES. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH NEAR RADIAL OUTFLOW, AND LOW TO MODERATE VERTICAL WIND SHEAR.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT ON THE FORECAST TO MAKE LANDFALL JUST SOUTH OF HANOI, VIETNAM, WITH A VERY SMALL CROSS-TRACK SPREAD OF ONLY 110KM THROUGH 24H. THE JTWC FORECAST TRACK IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS, BUT SLIGHTLY EQUATORWARD TOWARD THE BULK OF THE MODEL SOLUTIONS, WHICH ARE ON THE SOUTHERN EDGE OF THE AIDS ENVELOPE. UKMET, GFS, AND THE GFS ENSEMBLE REMAIN THE THREE MOST SIGNIFICANT POLEWARD OUTLIERS FROM CONSENSUS.

THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED NEAR 15.6N 137.1E IS NOW LOCATED NEAR 17.2N 133.5E, APPROXIMATELY 1260 KM EAST OF APARRI, PHILIPPINES. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH CONVECTION DISPLACED >165KM TO THE EAST, EXTENDING EQUATORWARD. A 081657Z AMSR2 89GHZ SATELLITE IMAGE REVEALS LOW LEVEL CLOUD LINES WRAPPING INTO THE LLCC, AND AN OVERALL ABSENCE OF ORGANIZATION TO THE DEEP CONVECTION ASSOCIATED WITH THE SYSTEM. INVEST 94W IS CURRENTLY EMBEDDED IN A BROAD MONSOON DEPRESSION WITH LIGHT (110 KM TO THE EAST. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH ROBUST POLEWARD OUTFLOW ALOFT OVER THE MAIN CONVECTION, AND MODERATE TO HIGH (20-30 KTS) VERTICAL WIND SHEAR. SEA SURFACE TEMPERATURES (SST) ARE FAVORABLE WITH WARM (30-31C) AND HIGH OCEAN HEAT CONTENT (>100 KJ PER SQUARE CM). GLOBAL MODELS INDICATE THAT THE TWO DOMINANT VORTEX CENTERS EMBEDDED IN THE MONSOON DEPRESSION (INVESTS 93W AND 94W) WILL STEADILY ORBIT ONE ANOTHER AND MERGE DUE TO THEIR CLOSE PROXIMITY (ABOUT 460 KM). DURING THIS CONSOLIDATION PHASE, THE SYSTEM IS EXPECTED TO GRADUALLY GAIN TROPICAL CYCLONE (WARM-CORE) CHARACTERISTICS WITH IMPROVED CENTRAL CONVECTION AND A RADIUS OF MAXIMUM WINDS LESS THAN 185KM. NUMERICAL MODELS FURTHER AGREE ON A SLOW, GENERALLY NORTHWESTWARD TRACK OVER THE NEXT 24 TO 48 HOURS. IT REMAINS UNCLEAR WHICH STORM WILL GAIN THE DOMINANT CENTER. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH.

INVEST 94W: TRACK AND INTENSITY GUIDANCE.

FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 145 NM EITHER SIDE OF A LINE FROM 16.5N 162.4E TO 18.3N 156.6E WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 18 TO 23 KNOTS. METSAT IMAGERY AT 091200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 16.6N 162.0E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 08 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 95W) PREVIOUSLY LOCATED NEAR 16.5N 164.3E IS NOW LOCATED NEAR 16.6N 162.0E, APPROXIMATELY 575KM WEST-NORTHWEST OF WAKE ISLAND. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS EXTENSIVE FLARING CONVECTION OBSCURING A LOW LEVEL CIRCULATION. A 090824Z PARTIAL ASCAT-A PASS SHOWS 15-20 KT WIND BARBS AROUND A LOW LEVEL CIRCULATION WITH GREATER THAN 20 KT WIND BARBS IN THE NORTHERN AND EASTERN PERIPHERY ASSOCIATED WITH GRADIENT FLOW AND CONVECTION, RESPECTIVELY. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT WITH ROBUST EQUATORWARD AND POLEWARD OUTFLOW, LOW (10-15KT) VERTICAL WIND SHEAR, AND WARM SEA SURFACE TEMPERATURES (29-30C). GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 95W WILL TRACK WEST-NORTHWESTWARD AS IT INTENSIFIES BEFORE RECURVING TO THE NORTH-NORTHEAST. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

INVEST 95W. TRACK AND INTENSITY GUIDANCE.

INVEST 95W. TRACK AND INTENSITY GUIDANCE.

FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 240 KM EITHER SIDE OF A LINE FROM 9.4N 91.8W TO 11.5N 99.5W WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. METSAT IMAGERY AT 081800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 9.5N 92.3W. THE SYSTEM IS MOVING WESTWARD AT 16 KNOTS. 2. REMARKS: MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

09/0245UTC.