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Tropical Storm Leslie Forecast Discussion Number 18
2018-09-30 22:38:34| National Hurricane Center (Atlantic)
Issued at 500 PM AST Sun Sep 30 2018 762 WTNT43 KNHC 302038 TCDAT3 Tropical Storm Leslie Discussion Number 18 NWS National Hurricane Center Miami FL AL132018 500 PM AST Sun Sep 30 2018 Leslie has generally changed little in organization today. The tropical storm continues to produce deep convection in a band to the southeast of the center, but there is a minimal amount of shower activity elsewhere. This asymmetric cloud pattern is due to about 25 kt of northwesterly wind shear. The initial intensity is again held at 45 kt, but some of the satellite estimates suggest that this could be a little generous. The global models show the upper-level pattern becoming more favorable over Leslie in about a day, which combined with warmer SSTs should allow Leslie to gradually strengthen during the next 2 to 3 days. After that time, the storm is expected to move northeastward back over its previous track and cooler waters partly caused by its own upwelling. These conditions should end the strengthening trend and induce some weakening. The NHC intensity forecast is largely an update of the previous one and in line with the IVCN, FSSE, and HCCA consensus models. Leslie is drifting to the southwest, with the latest initial motion estimate being 240/4 kt. The storm is forecast to remain in very weak steering currents, and Leslie will likely drift southward to southwestward during the next few days on the east side of a mid-level ridge. Thereafter, a developing trough to the southwest of Leslie should cause the system to move northeastward at a slightly faster pace. The models continue to shift back and forth each cycle, which is not surprising given the weak steering. This forecast is adjusted a little to the left of the previous one to come into better agreement with the latest models. The bottom line is that Leslie is forecast to meander over the central Atlantic for the next several days. Large swells generated by Leslie when it was a strong extratropical low will continue to affect the east coast of the United States and most of the Greater and Lesser Antilles for another day or two. These swells could cause life-threatening surf and rip currents. Although the swells will diminish some by mid-week, they will likely remain hazardous for the same locations through the forecast period due to Leslie's slow motion. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 33.5N 53.2W 45 KT 50 MPH 12H 01/0600Z 33.3N 53.7W 50 KT 60 MPH 24H 01/1800Z 32.9N 54.3W 55 KT 65 MPH 36H 02/0600Z 32.1N 55.0W 60 KT 70 MPH 48H 02/1800Z 31.3N 55.3W 65 KT 75 MPH 72H 03/1800Z 31.0N 54.7W 65 KT 75 MPH 96H 04/1800Z 33.5N 53.5W 60 KT 70 MPH 120H 05/1800Z 36.5N 52.0W 60 KT 70 MPH $$ Forecaster Cangialosi
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