WNP: TD 09W forecast to intensify to Typhoon Cat1 by 72h, Invest 99W under close watch//06E(FELICIA): powerful Hurricane Cat4, 17/09utc updates

INVEST 99W NOW ON THE MAP AND UP-GRADED TO MEDIUM. ON THE OTHER HAND JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE ON 09W. BULLETINS.

TD 09W. WARNING 5 ISSUED AT 17/09UTC.SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 09W IS TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF THE SUBTROPICAL RIDGE(STR) BUT IS EXPECTED TO GRADUALLY TURN WEST-NORTHWESTWARD AS A DEEP UPPER LOW CURRENTLY LOCATED WEST OF KYUSHU FILLS AND SHIFTS WEST ALLOWING THE STR TO BUILD OVER THE EAST CHINA SEA BY 48H. TD 09W IS CURRENTLY STRUGGLING TO CONSOLIDATE DUE PRIMARILY TO THE CONVERGENCE ALOFT AND DRY AIR ENTRAINMENT, THEREFORE, TD 09W SHOULD SLOWLY INTENSIFY THROUGH 24H. AFTER 24H, ENVIRONMENTAL CONDITIONS SHOULD GRADUALLY IMPROVE AS THE UPPER LOW AND CONVERGENCE ALOFT WEAKENS ALLOWING THE SYSTEM TO VENT AND SUSTAIN MORE CENTRALIZED DEEP CONVECTION, WHICH WILL MOISTEN THE MID-LEVELS. THIS SHOULD LEAD TO A FASTER RATE OF INTENSIFICATION WITH A PEAK OF 85 KNOTS/CAT2 ANTICIPATED BY 120H.

TD 09W.SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED, BROAD LOW-LEVEL CIRCULATION CENTER (LLCC) POSITIONED ALONG THE WESTERN EDGE OF A SWATH OF DEEP CONVECTION ASSOCIATED WITH AN EXTENSIVE SWATH OF CONVERGENT SOUTHERLY LOW-LEVEL FLOW. A 170415UTC AMSR2 89GHZ COMPOSITE MICROWAVE IMAGE REVEALS WEAKLY-DEFINED SHALLOW BANDING WRAPPING AROUND AN ELONGATED, DEFINED LLCC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON MSI AND THE AFOREMENTIONED AMSR2 IMAGE. THE INITIAL INTENSITY OF 30 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE DVORAK ESTIMATE FROM KNES AND A 162335Z ASCAT-A PARTIAL IMAGE SHOWING A SWATH OF 25-30 KNOT SOUTHERLY WINDS OVER THE EASTERN PERIPHERY. ENVIRONMENTAL ANALYSIS INDICATES MARGINALLY FAVORABLE CONDITIONS WITH CONVERGENT UPPER-LEVEL WESTERLIES AND MID-LEVEL DRY AIR ENTRAINMENT OVER THE WESTERN SEMICIRCLE OFFSET BY ROBUST POLEWARD AND EQUATORWARD OUTFLOW AND WARM SST VALUES.

TD 09W.MODEL DISCUSSION: DUE TO THIS EVOLVING SYNOPTIC PATTERN, THERE IS INCREASING UNCERTAINTY IN THE TRACK FORECAST AFTER 48H. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT THROUGH 48H WITH A 165KM SPREAD IN SOLUTIONS AT 48H. AFTER 48H, MODEL GUIDANCE DIVERGES WITH JGSM INDICATING A FASTER NORTHWESTWARD TRACK OVER SHANGHAI, CHINA, AND GFS AND UKMET INDICATING A SHARPER WESTWARD TURN TOWARD NORTHERN TAIWAN. THE BULK OF THE GUIDANCE SUPPORTS THE JTWC TRACK FORECAST WITH LOW CONFIDENCE IN THE EXTENDED PERIOD. THERE IS LOW CONFIDENCE IN THE JTWC INTENSITY FORECAST IN THE EXTENDED PERIOD WITH A LARGE SPREAD IN INTENSITY GUIDANCE ASSOCIATED WITH THE COMPLEX, EVOLVING ENVIRONMENT.

INVEST 99W. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS BROAD TURNING WITH FORMATIVE CONVECTIVE BANDING OVER THE NORTHEAST QUADRANT. A 170232Z METOP-B ASCAT IMAGE REVEALS 15KNOT WIND BARBS IN THE NORTHERN SEMICIRCLE AND WEAKER WINDS ELSEWHERE, WRAPPING INTO A BROAD LOW LEVEL CIRCULATION CENTER (LLCC). ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS WITH GOOD WESTWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR AND WARM (31-32C) SEA SURFACE TEMPERATURES.

INVEST 99W. GFS AND ICON BOTH INDICATE INVEST 99W WILL CONSOLIDATE AND INTENSIFY AS IT TRACKS TO THE WEST- NORTHWEST OVER THE NEXT 24-48 HOURS.

17/00UTC.

EASTERN NORTH PACIFIC. HU 06E(FELICIA). WARNING 12 ISSUED AT 17/04UTC. THIS SYSTEM IS A POWERFUL CATEGORY 4 HURRICANE MONITORED OVER OPEN WATERS.

06E(FELICIA). GUIDANCE.

06E(FELICIA). DVORAK=5.5/5.5 AT 17/06UTC.

17/00UTC.