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Tropical Storm Leslie Forecast Discussion Number 34
2018-10-04 22:33:46| National Hurricane Center (Atlantic)
Issued at 500 PM AST Thu Oct 04 2018 000 WTNT43 KNHC 042033 TCDAT3 Tropical Storm Leslie Discussion Number 34 NWS National Hurricane Center Miami FL AL132018 500 PM AST Thu Oct 04 2018 Leslie has changed little in convective structure today. Visible imagery shows occasional appearances of an eye inside an area of central convection, with a complex of outer bands wrapping around this inner feature. Infrared imagery, though, suggests that the convection is relatively shallow. Despite the lack of change in the convective pattern, scatterometer data shows there have been significant changes in the wind structure. The strongest winds are now in a band about 90-100 n mi from the center, with the winds in the inner core being notably weaker. This suggest the possibility that Leslie is trying to undergo an eyewall replacement, albeit one with a very large outer eyewall. Based on the scatterometer data and slightly decreased satellite intensity estimates, the initial intensity is reduced to 60 kt. There is little change to the intensity forecast philosophy, the intensity forecast guidance, or the intensity forecast. While the vertical shear should remain light through the forecast period, the forecast track takes the center away from 26C sea surface temperatures and over 24-25C temperatures, and this should cause a gradual weakening for the next several days. There are major changes to the initial and forecast wind radii based on the scatterometer data and the analyzed initial size. The initial motion is 355/10. In the short term, Leslie will be steered northward between a mid-level ridge over the central Atlantic and a mid- to upper-level trough seen in water vapor imagery north of Bermuda. A decrease in forward speed should occur from 24-36 h as the trough moves south and a second ridge develops to the west of the tropical cyclone. Beyond 36 h, Leslie is expected to move eastward to east-southeastward at a faster forward speed along the southern edge of the mid-latitude westerlies. Overall, the new forecast track is close to the previous track through 48 h, then a little north of the old track after that time. However, there is an increased spread in the guidance in both the track and the forward speed near the end of the forecast period, and confidence is decreasing for this part of the 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 begin to increase near the coasts of New England and Atlantic Canada on Friday. 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 04/2100Z 33.3N 57.5W 60 KT 70 MPH 12H 05/0600Z 34.9N 58.0W 60 KT 70 MPH 24H 05/1800Z 36.1N 58.2W 60 KT 70 MPH 36H 06/0600Z 36.8N 57.5W 55 KT 65 MPH 48H 06/1800Z 36.7N 55.9W 55 KT 65 MPH 72H 07/1800Z 36.0N 52.5W 50 KT 60 MPH 96H 08/1800Z 34.5N 48.5W 50 KT 60 MPH 120H 09/1800Z 32.5N 44.5W 50 KT 60 MPH $$ Forecaster Beven
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