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Tropical Storm Melissa Forecast Discussion Number 6
2019-10-12 22:34:25| National Hurricane Center (Atlantic)
Issued at 500 PM AST Sat Oct 12 2019 000 WTNT44 KNHC 122034 TCDAT4 Tropical Storm Melissa Discussion Number 6 NWS National Hurricane Center Miami FL AL142019 500 PM AST Sat Oct 12 2019 Convection has continued to persist near the center of Melissa throughout the day, and only in the past few hours have the affects of increasing westerly shear begun to erode the convection from the western side of the cyclone. A pair of scatterometer passes late this morning showed that the wind field associated with the storm had contracted, with the strongest winds occurring within 50 n mi of the center. They also revealed that the radius of maximum winds had decreased to 20 n mi. Based on these data along with a tropical structure apparent in satellite and microwave data, it is likely that Melissa completed a transition to a tropical cyclone at some point this morning. A recent Dvorak classification from TAFB, an objective estimate from UW-CIMSS ADT, and an earlier scatterometer pass all support an initial intensity of 45 kt for this advisory. The westerly shear beginning to affect Melissa is expected to gradually increase over the next few days. Through tonight, the cyclone will move over waters of 23-24 C. In addition, the upper trough over the storm that has aided in maintaining its convection will weaken and lift northeast of the cyclone over the next day or so. The combination of these factors should cause Melissa to weaken, and the cyclone is forecast to become a post-tropical remnant low by Sunday. The global model intensity forecasts appear to be capturing the strongest winds in a frontal zone well-removed to the northeast of Melissa and not directly associated with the cyclone itself. Thus, the NHC forecast is very similar to the previous one, and continues to be lower than the global model guidance. Melissa is moving east-northeastward, or 070/10 kt. The increasing westerly flow will cause the cyclone to gradually accelerate through Monday. This motion will continue, with a slight turn to the east in a few days, just before the cyclone is absorbed by a frontal zone. The new NHC track forecast is close to the previous one and in the middle of the various consensus aids. Ongoing hazards from coastal flooding will continue to be covered by non-tropical products from local National Weather Service forecast offices. Key Messages: 1. Although Melissa is forecast to weaken and move away from the east coast, minor to moderate coastal flooding is still expected along portions of the U.S. Mid-Atlantic and southeastern coasts around times of high tide for the remainder of the weekend. For more information, see products issued by local National Weather Service forecast offices at weather.gov. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 38.4N 65.6W 45 KT 50 MPH 12H 13/0600Z 39.0N 63.5W 35 KT 40 MPH 24H 13/1800Z 39.8N 60.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 14/0600Z 40.7N 55.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 14/1800Z 41.6N 51.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 15/1800Z 42.4N 39.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 16/1800Z...ABSORBED BY A FRONTAL ZONE $$ Forecaster Latto
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