Issued at 1100 AM AST Sat Oct 12 2019 000WTNT44 KNHC 121449TCDAT4Subtropical Storm Melissa Discussion Number 5NWS National Hurricane Center Miami FL AL1420191100 AM AST Sat Oct 12 2019A small area of deep convection has persisted for the past severalhours over and around the center of Melissa. Recent AMSU microwavetemperature data indicate that a warm core exists at least above 550mb. It is uncertain, however, if this warm core is due to theintrusion of warmer temperatures aloft embedded in the upper troughover Melissa, or if the warming was induced by convective feedback.If deep convection persists into the afternoon, then it is morelikely that the warm core is due to the convection, and Melissacould transition to a tropical cyclone by that time. Based onnearby surface observations, the wind field immediately surroundingMelissa has contracted, with no evidence of gale-force winds beyond150 n mi from the center. Given the convection near the center, thestrongest winds are now most likely occurring in that region. Thelatest Hebert-Poteat subtropical satellite intensity estimate fromTAFB is 45-50 kt, and UW-CIMSS ADT and SATCON tropical estimates are41 kt and 42 kt, respectively. Therefore, the initial intensity isbeing held at 45 kt.The upper trough over Melissa is forecast to weaken and liftnortheastward through tonight, which would remove the upper-levelsupport for the subtropical storm. Increasing westerly wind shearand progressively cooler SSTs should weaken the cyclone over thenext few days, with Melissa moving over waters of 23-24 C tonight.This should cause the cyclone to lose its convection and transitionto a remnant low by Sunday. The post-tropical cyclone is expectedto persist for a couple of days just ahead of a frontal zone beforeit is finally absorbed by the front in 3-4 days. The NHC forecastis near the consensus aids at 12 hours, but a little below thatguidance through Sunday, as the global models appear to be capturingthe strongest winds in a frontal zone well-removed to the northeastof Melissa, and not directly associated with the cyclone itself.Melissa is now moving east-northeastward, or 070/08 kt. Increasingwesterly flow will cause the cyclone to accelerate tonight throughMonday. This motion will continue until the cyclone is absorbed bya frontal zone. The new NHC track forecast is close to the previousone and in the middle of the various consensus aids.Ongoing hazards from coastal flooding will continue to be covered bynon-tropical products from local National Weather Service forecastoffices.Gale-force winds that extend from offshore of Nova Scotia eastwardover the Atlantic are not included in the wind radii since they areassociated with a frontal boundary.Key Messages:1. Melissa is expected to slowly weaken and move away from theU.S. east coast today, resulting in a gradual decrease in wind andcoastal flooding impacts.2. Minor to moderate coastal flooding is still expected alongportions of the U.S. Mid-Atlantic and southeastern New Englandcoasts around times of high tide today. For more information,see products issued by local National Weather Service forecastoffices at weather.gov.FORECAST POSITIONS AND MAX WINDSINIT 12/1500Z 38.1N 67.0W 45 KT 50 MPH 12H 13/0000Z 38.7N 65.2W 40 KT 45 MPH 24H 13/1200Z 39.6N 62.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 14/0000Z 40.3N 58.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 14/1200Z 41.0N 54.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 15/1200Z 42.2N 45.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 16/1200Z...ABSORBED BY A FRONTAL ZONE$$Forecaster Latto

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