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Tropical Storm Leslie Forecast Discussion Number 36
2018-10-05 10:56:19| National Hurricane Center (Atlantic)
Issued at 500 AM AST Fri Oct 05 2018 000 WTNT43 KNHC 050856 TCDAT3 Tropical Storm Leslie Discussion Number 36 NWS National Hurricane Center Miami FL AL132018 500 AM AST Fri Oct 05 2018 Leslie's structure has evolved somewhat just within the past 6 hours. Deep convection has redeveloped near the low-level center, although it is displaced a bit to the north due to some southerly shear. The cyclone's circulation remains quite large, and earlier ASCAT data indicated that the radius of maximum winds is about 90-100 n mi away from the center. Since there is some inner-core convection again, the initial intensity remains 55 kt based on the ASCAT data. Leslie has gained some speed and has turned toward the north-northwest, now with an initial motion of 345/12 kt. A general northward motion should continue for the next 12-24 hours, but then Leslie will reach the mid-latitude westerlies and make an abrupt turn toward the east by 36 hours. After that time, Leslie is expected to make some significant eastward progress, although the global models are showing several shortwave troughs in the westerlies imparting a southeastward motion on Leslie by days 4 and 5. In fact, some of the models have shifted significantly southward by the end of the forecast period, leaving the previous official forecast near the northern edge of the guidance envelope. Due to this shift, the new NHC track prediction has been adjusted southward on days 3-5, although it does not yet show as much southward motion as indicated by the normally reliable ECMWF, HCCA, and TVCN multi-model consensus. Leslie doesn't appear to have to contend with much shear during the next 3 days or so, but with such a large wind field mixing the ocean around it, marginal sea surface temperatures are likely to keep the intensity steady. By days 3 and 4, an increase in shear could cause some slight weakening. The models are in very good agreement in showing little to any change in Leslie's intensity during the next 5 days, and that is largely what is indicated in the NHC forecast. Large swells generated by Leslie are expected to continue during the next few days across the southeastern coast of the United States, Bermuda, the Bahamas, and the Greater and Lesser Antilles. These swells will also increase near the coasts of New England and Atlantic Canada later today. Please consult products from your local weather office as these conditions could cause life- threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 35.9N 58.3W 55 KT 65 MPH 12H 05/1800Z 36.9N 58.4W 50 KT 60 MPH 24H 06/0600Z 37.4N 57.6W 50 KT 60 MPH 36H 06/1800Z 37.4N 55.8W 50 KT 60 MPH 48H 07/0600Z 37.0N 53.7W 50 KT 60 MPH 72H 08/0600Z 35.7N 49.7W 45 KT 50 MPH 96H 09/0600Z 33.5N 45.5W 45 KT 50 MPH 120H 10/0600Z 31.5N 42.0W 50 KT 60 MPH $$ Forecaster Berg
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