Western Pacific: TY 19W(CHANTHU) displaying eye-wall cycles,TD 18W(CONSON) nearing Dan Nang//Eastern Pacific & Atlantic: TCFA's, 12/03utc updates

TD 19W(CONSON). WARNING 25 ISSUED AT 12/03UTC.SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 18W IS FORECAST TO MAINTAIN A QUASI-STATIONARY MOTION THROUGH 12H UNDER A COMPETING STEERING ENVIRONMENT. AFTER 12H, THE SUBTROPICAL RIDGE TO THE NORTH IS EXPECTED TO STRENGTHEN, ALLOWING TD 18W TO ACCELERATE WEST-NORTHWESTWARD INTO VIETNAM. ONCE THE SYSTEM TRACKS OVER THE MOUNTAINOUS TERRAIN OF VIETNAM, IT'S EXPECTED TO RAPIDLY DISSIPATE.

TD 18W(CONSON).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS FLARING DEEP CONVECTION DISPLACED WEST OF AN EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). ANIMATED RADAR IMAGERY INDICATES A QUASI-STATIONARY SYSTEM OVER WATER WITH A WELL-ORGANIZED LLCC AND TIGHTLY-WRAPPED RAINBANDS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EIR AND RADAR IMAGERY. THE INITIAL INTENSITY OF 30 KNOTS IS ASSESSED WITH HIGH CONFIDENCE HEDGED JUST BELOW THE PGTW DVORAK ESTIMATE DUE TO THE WEAK CONVECTIVE STRUCTURE. UPPER-LEVEL CONDITIONS ARE MARGINAL WITH STRONG (25 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS) AND DIFFLUENT FLOW ALOFT.

TD 18W(CONSON). MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE BULK OF THE MODEL GUIDANCE SUPPORTS THE SHORT DURATION QUASI-STATIONARY TRACK MOTION THEN AN ACCELERATED TRACK NORTHWESTWARD TO WEST-NORTHWESTWARD AFTER 12H. HOWEVER, DUE TO THE UNCERTAINTY IN THE EXACT TRACK, THERE IS MEDIUM CONFIDENCE IN THE JTWC FORECAST TRACK. THE JTWC INTENSITY FORECAST IS OBVIOUSLY LINKED TO THE TIMING OF THE LANDFALL, WHICH IS EXPECTED NEAR 24H WITH DISSIPATION EXPECTED BY 48H.

TY 19W(CHANTHU). WARNING 24 ISSUED AT 12/03UTC.SIGNIFICANT FORECAST CHANGES: THE SYSTEM IS NOW EXPECTED TO BEGIN EXTRA-TROPICAL TRANSITION AT 120H NEAR CHEJU ISLAND. FORECAST DISCUSSION: TY 19W WILL TRACK POLEWARD ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE THROUGH 72H. THE SYSTEM SHOULD STEADILY WEAKEN AS IT INTERACTS WITH TAIWAN AND UPPER-LEVEL DIVERGENCE DECREASES AS THE SYSTEM BEGINS TO INTERACT WITH AN UPPER-LEVEL SUBTROPICAL TROUGH EXPECTED TO DEEPEN OVER EASTERN CHINA OVER THE NEXT TWO DAYS. IN THE EXTENDED PERIOD, TY 19W IS FORECAST TO TRACK EAST-NORTHEASTWARD WITHIN WESTERLY FLOW AND WILL WEAKEN TO TS STRENGTH (40 KNOTS) BY 120H. NUMERICAL MODEL GUIDANCE INDICATES A FAIRLY ATYPICAL MIDLATITUDE PATTERN WITH WEAK TO MODERATE SUBTROPICAL WESTERLIES AND THE FRONTAL ZONE TO THE NORTH OVER THE KOREAN PENINSULA, THEREFORE, EXTRATROPICAL TRANSITION IS NOT EXPECTED UNTIL 120H WHEN THE SYSTEM FIRST BEGINS TO INTERACT WITH THE BAROCLINIC ZONE. ADDITIONALLY, TRACK SPEEDS SHOULD BE UNUSUALLY SLOW THROUGH 120H.

TY 19W(CHANTHU).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TY 19W CONTINUES TO EXPERIENCE A SERIES OF FAIRLY QUICK EYEWALL REPLACEMENT CYCLES (ERC) INCLUDING THE ONGOING ERC, WHICH IS EVIDENT IN AN 112300Z SSMIS 91GHZ COMPOSITE IMAGE. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY, ANIMATED RADAR IMAGERY AND THE 112300Z SSMIS 91GHZ IMAGE DEPICT A SMALL CORE OF INTENSE CONVECTION SURROUNDING A 11KM EYE WITH EXTENSIVE SPIRAL BANDING. AS OF 120200Z, TY 19W'S CENTER IS LOCATED ABOUT 46KM WEST OF YONAGUNIJIMA (47912), WHICH IS REPORTING 10-MINUTE SUSTAINED SURFACE WINDS AT 45 KNOTS WITH AN SLP VALUE OF 989.4MB. POLEWARD AND EQUATORWARD OUTFLOW HAVE REMAINED ROBUST WITH LOW VERTICAL WIND SHEAR (VWS) AND WARM SST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EIR IMAGERY. THE INITIAL INTENSITY OF 110 KTS/CAT 3 IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW AND KNES DVORAK CURRENT INTENSITY ESTIMATES OF 5.5-6.0 AND THE ADT ESTIMATE. THE RJTD DATA-T IS AT A T6.0 (115 KNOTS) WHILE THE CURRENT INTENSITY REMAINS CONSERVATIVE AT 7.0 (140 KNOTS).

TY 19W(CHANTHU).TY 19W CONTINUES TO EXPERIENCE A SERIES OF FAIRLY QUICK EYEWALL REPLACEMENT CYCLES (ERC) INCLUDING THE ONGOING ERC, WHICH IS EVIDENT IN AN 112300Z SSMIS 91GHZ COMPOSITE IMAGE

TY 19W(CHANTHU).MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH 48H WITH A 130KM SPREAD IN SOLUTIONS AT 48H. AFTER 48H, THERE IS INCREASING UNCERTAINTY WITH WEAKER STEERING FLOW THUS MEDIUM OVERALL TRACK CONFIDENCE. IN THE EXTENDED PERIOD, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST WITH LARGE SPREAD IN MODEL SOLUTIONS. CROSS-TRACK SPREAD IS ABOUT 280KM AT 120H WITH THE GFS ENSEMBLE MEAN (GEFS) AND UKMET TRACKING INTO THE SYSTEM INTO NORTHERN KYUSHU WHILE THE BULK OF THE GUIDANCE IS OVER CHEJU ISLAND AND THE SOUTHERN PORTIONS OF SOUTH KOREA. ALONG-TRACK TRACK SPEEDS HAVE INCREASED REFLECTING THE STRONGER UPPER-LEVEL WESTERLY FLOW DEVELOPING AFTER 96H. THERE IS LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST DUE TO THE COMPLEX INTERACTIONS WITH THE AFOREMENTIONED TROUGH AND SUBTROPICAL WESTERLIES AS WELL AS INTERACTION WITH TAIWAN AND EASTERN CHINA.

TY 19W(CHANTHU). HWRF AT 11/18UTC. INTENSITY GUIDANCE: 108KNOTS AT +0H.

12/00UTC.

INVEST 95B. 11/18UTC. THE AREA OF CONVECTION (INVEST 95B) PREVIOUSLY LOCATED NEAR 16.0N 88.0E IS NOW LOCATED NEAR 19.5N 88.9E, APPROXIMATELY 340 KM SOUTH OF KOLKATA, INDIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS SCATTERED CONVECTION TO THE WEST OF A BROAD EXPOSED LOW LEVEL CIRCULATION. ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT DUE TO EASTERLY DIFFLUENT FLOW ASSOCIATED WITH A WEAK TROPICAL EASTERLY JET (TEJ), MODERATE VERTICAL WIND SHEAR (15-20 KT) AND WARM SEA SURFACE TEMPERATURES (29-30C). MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 997 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.

INVEST 95B. GLOBAL MODELS ARE IN AGREEMENT THAT INVEST 95B WILL TRACK NORTHWESTWARD WITH A SMALL WINDOW TO INTENSIFY DUE TO A WEAKENING TEJ IN THE NORTHERN BAY OF BENGAL.

EASTERN PACIFIC. INVEST 97E. TROPICAL CYCLONE FORMATION ALERT ISSUED AT 11/23UTC.1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 175 NM EITHER SIDE OF A LINE FROM 11.5N 97.7W TO 15.5N 100.0W 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 111800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 11.5N 97.7W. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 07 KM/H. 2. REMARKS: AN AREA OF CONVECTION (INVEST 97E) HAS PERSISTED NEAR 11.5N 97.7W, APPROXIMATELY 3080 KM SOUTHEAST OF SAN DIEGO. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A NARROW BAND OF DEEP CONVECTION WRAPPING INTO A BROAD LOW LEVEL CIRCULATION CENTER. UPPER LEVEL ANALYSIS INDICATES THE DISTURBANCE IS LOCATED UNDER AN AREA OF BROAD DIFFLUENCE WITH LOW TO MODERATE VERTICAL WIND SHEAR.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.

INVEST 97E. GLOBAL MODELS INDICATE THAT THE SYSTEM WILL SLOWLY DEVELOP AS IT TRACKS TOWARDS THE COAST OF SOUTHERN MEXICO.

ATLANTIC. INVEST 94L. TROPICAL CYCLONE FORMATION ALERT ISSUED AT 11/20UTC.FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 185 KM EITHER SIDE OF A LINE FROM 18.6N 93.3W TO 22.3N 96.6W WITHIN THE NEXT 00 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 15 TO 20 KNOTS. METSAT IMAGERY, SYNOPTIC DATA AND RADAR DATA AT 110340Z INDICATE THAT A CIRCULATION CENTER IS LOCATED NEAR 18.6N 93.2W. THE SYSTEM IS MOVING NORTHWESTWARD AT 22 KM/H. 2. A BROAD AREA OF LOW PRESSURE LOCATED ALONG THE COAST OF SOUTHEASTERN MEXICO IS PRODUCING A LARGE AREA OF SHOWERS AND THUNDERSTORMS THAT ARE EXTENDING OVER THE BAY OF CAMPECHE. ENVIRONMENTAL CONDITIONS OVER THE SOUTHERN GULF OF MEXICO ARE EXPECTED TO BECOME MORE FAVORABLE FOR DEVELOPMENT OF THE SYSTEM AS IT EMERGES OVER THE BAY BY TONIGHT. AS THE DISTURBANCE MOVES GENERALLY NORTHWESTWARD AT 5 TO 10 KT SUNDAY, FURTHER DEVELOPMENT IS EXPECTED AND A TROPICAL DEPRESSION IS LIKELY TO FORM OVER THE SOUTHERN GULF OF MEXICO BY SUNDAY NIGHT, OR EARLY MONDAY.

INVEST 94L. GUIDANCE.

12/08UTC.