Busy map: TC 14S(VERNON)peaking within 12h//over-land TC 15S(ANIKA)//TC 17S final warning//TC 18P peaking within 12h//Invest 90B, 03/03utc

JTWC IS ISSUING 6HOURLY WARNINGS ON TC 18P AND 12HOURLY WARNINGS ON TC 14S(VERNON). 3HOURLY SARELLITE BULLETINS ARE ISSUED ON 14S,15S,17S,18P.

03/0315UTC.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 14S WILL CONTINUE TRACKING SOUTH-SOUTHWEST FOR THE NEXT 24 TO 48 HOURS, ALONG THE NORTHWESTERN PERIPHERY OF THE STEERING RIDGE TO THE SOUTHEAST IN THE DIRECTION OF A WEAKNESS IN THE RIDGE INDUCED BY THE APPROACH OF A MID-LATITUDE TROUGH. THE SYSTEM WILL TURN MORE SOUTHWARD BY 48H. NO SIGNIFICANT ENVIRONMENTAL CHANGES ARE EXPECTED IN THE FIRST 36 HOURS OF THE FORECAST, WITH SUPPORTIVE SSTS AND ROBUST OUTFLOW COMPETING WITH PERSISTENT NORTHERLY SHEAR AND DRY AIR ENCROACHMENT FROM THE NORTH. THE SYSTEM IS FORECAST TO BRIEFLY INTENSITY TO 55 KNOTS IN THE NEXT 12 HOURS, BUT THEN BEGIN A STEADY WEAKENING TREND AS THE SHEAR INCREASES AND SSTS BEGIN TO DECREASE BY 48H WHILE THE SYSTEM BEGINS SUBTROPICAL TRANSITION BY 60H. TC 14S WILL COMPLETE TRANSITION INTO A STRONG GALE-FORCE SUBTROPICAL LOW NO LATER THAN 72H.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS RAGGED CONVECTION HAS FLARED CONTINUOUSLY WITH CLOUD TOPS IN A WARMING PHASE. A 032300Z SSMIS 89GHZ MICROWAVE IMAGE SHOWED THE RAGGED LLCC WITH THE MAJORITY OF THE CONVECTIVE ACTIVITY DISPLACED FROM CENTER TO THE SOUTH, WITH WEAK LOW LEVEL BANDING FEATURES ON THE NORTH SIDE THE CIRCULATION, PROVIDING HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY OF 50 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE SUSTAINED 6-HR EIR CONVECTIVE STRUCTURE. GEOSTATIONARY WATER VAPOR IMAGERY SUGGESTS A WEDGE OF DRY AIR CONTINUED TO WRAP IN CLOSER TO THE CORE FROM THE NORTHEAST. CIMSS VWS ANALYSIS REVEALS THE SYSTEM IS MOVING INTO 20-25 KNOTS OF PERSISTENT SHEAR. THE ENVIRONMENT IS MARGINAL WITH WARM SSTS AND ROBUST POLEWARD OUTFLOW OFFSET BY INCREASING VWS AND INFLUX OF DRY AIR. THE CYCLONE IS TRACKING ALONG THE NORTHWEST PERIPHERY OF THE STR TO THE SOUTHEAST

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL VERY GOOD AGREEMENT THROUGH THE FORECAST PERIOD, WITH LESS CONFIDENCE AFTER 48H WITH A GRADUAL SPREAD TO 330 KM BY 72H. THE TRACK LIES ON THE WESTERN SIDE OF THE CONSENSUS WITH HIGH CONFIDENCE. THE INTENSITY FORECAST LIES NEAR THE CONSENSUS MEAN THROUGH THE FORECAST PERIOD. INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, WITH A PEAK OF 55 KNOTS BY 12H FOLLOWED BY A STEADY WEAKENING TREND THEREAFTER.

TROPICAL CYCLONE (TC) 17S (SEVENTEEN), LOCATED APPROXIMATELY 690 KM SOUTHEAST OF JAKARTA, INDONESIA, HAS TRACKED EAST- NORTHEASTWARD AT 07 KM/H OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION HAS BECOME MORE SHALLOW AND DISORGANIZED AS IT SHEARED FURTHER WESTWARD, NOW 140 KM, FROM A WEAK AND FULLY EXPOSED LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLC. THE INITIAL INTENSITY OF 25 KTS IS BASED ON THE PGTW DVORAK ESTIMATE OF T1.5/25KTS AND CONSISTENT WITH THE 6-HR EIR WEAKENING TREND. ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH STRONG (25KT+) VERTICAL WIND SHEAR OFFSETTING THE WARM SST AND MODERATE WESTWARD UPPER LEVEL OUTFLOW. TC 17S WILL DRIFT SOUTHEASTWARD AND CONTINUE TO UNRAVEL AND DISSOLVE. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TC 18S WILL BECOME QUASI STATIONARY (QS) UP TO 24H AS THE NEAR EQUATORIAL (RIDGE) NER RECEDES AND A WEAK SUBTROPICAL RIDGE (STR) BUILDS TO THE EAST. AFTER 24H THE STR WILL ASSUME STEERING AND DRIVE THE SYSTEM WEST-SOUTHWESTWARD. THE MARGINAL ENVIRONMENT WILL FUEL A SLIGHT INTENSIFICATION TO 40KTS BY 12H. AFTERWARD, INCREASING VWS, EXACERBATED BY THE REVERSAL IN STORM MOTION, WILL RESULT IN WEAKENING AS THE CONVECTION BECOMES DECOUPLED EASTWARD. BY 48H, OR SOONER, THE SYSTEM WILL BE REDUCED TO 30KTS, BELOW JTWC WARNING CRITERIA, AND DISSIPATE.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS AN EXPANSIVE SYSTEM WITH THE CENTRAL CONVECTION STRUGGLING TO STAY INTACT WITH THE MODERATE WESTERLY VWS. THE LOW LEVEL CIRCULATION IS BROAD AND PARTIALLY EXPOSED ON THE LEFT SIDE. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON LOW CLOUD TRACING IN THE MSI LOOP. THE INITIAL INTENSITY IS BASED ON THE 022155Z PARTIAL ASCAT PASS SHOWING 35-KT WIND BARBS ALONG THE NORTHEAST AND SOUTHEAST QUADRANTS. ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MODERATE VWS OFFSETTING THE STRONG EASTWARD OUTFLOW AND WARM SST. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE NER TO THE NORTH.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL AGREEMENT WITH THE TRACK FORECAST; HOWEVER, GIVEN THE UNCERTAINTY DURING THE QS MOTION, THERE IS LOW CONFIDENCE IN THE INITIAL JTWC TRACK FORECAST ON THIS SYSTEM.

THE AREA OF CONVECTION (INVEST 90B) PREVIOUSLY LOCATED NEAR 4.8N 87.6E IS NOW LOCATED NEAR 5.0N 86.0E, APPROXIMATELY 700 KM EAST-SOUTHEAST OF COLOMBO, SRI LANKA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 021225Z SSMIS 91GHZ MICROWAVE PASS REVEALS AN OBSCURED BUT WELL DEFINED LOW LEVEL CIRCULATION WITH DEEP CONVECTION ON THE NORTHWESTERN PERIPHERY. THE OVERALL ENVIRONMENT IS MARGINAL AS 90B IS AN AREA OF MODERATE TO HIGH (20-30 KT) VERTICAL WIND SHEAR, OFFSET BY WARM SEA TEMPURATURES (29-30C) AND STRONG POLEWARD OUTFLOW. GLOBAL MODELS AGREE THAT THE SYSTEM WILL TRACK WESTNORTHWEST GRADUALLY CONSOLIDATING AND STRENGTHING OVER THE NEXT 36-48 HOURS. AS IT REACHES THE NORTHERN PORTION OF SRI LANKA AND THE SOUTH EASTERN COAST OF INDIA THE WINDOW FOR 90B TO REACH TROPICAL STORM STRENGTH IS LIMITED WITH GLOBAL MODELS INDICATING IT WILL REACH LAND AT ROUGHLY THE SAME INSTANCE. 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 REMAINS LOW.