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Tropical Storm Leslie Forecast Discussion Number 46
2018-10-07 22:36:38| National Hurricane Center (Atlantic)
Issued at 500 PM AST Sun Oct 07 2018 000 WTNT43 KNHC 072036 TCDAT3 Tropical Storm Leslie Discussion Number 46 NWS National Hurricane Center Miami FL AL132018 500 PM AST Sun Oct 07 2018 Late-arriving ASCAT data from shortly after 1200 UTC indicated that Leslie is still producing winds of just below 45 kt, primarily in the southwest and northeast quadrants of the tropical storm. Assuming at least a little undersampling has occurred, this would support an initial intensity of 45 or 50 kt, while an average of more recent intensity estimates from SAB, TAFB, and the UW-CIMSS is 50 kt. The initial value is therefore held at 50 kt. Regardless of the exact initial intensity of Leslie, only slight fluctuations are expected over the next 24 to 36 hours while Leslie is over fairly cool SSTs, in part because it will be crossing its own previous track multiple times. Beyond 48 h, the intensity guidance is now in better agreement that some intensification will occur, and Leslie is forecast to become a hurricane once again by the end of the week. The NHC intensity forecast is a little higher than the previous advisory by the end of the forecast period, and is close to IVCN at all times. Leslie is still moving east-southeastward with an initial speed of 9 kt, and this general motion will likely continue for at least the next day or two while the tropical storm is steered by westerly flow associated with a mid-latitude trough to its north. Most of the global models still forecast that Leslie will separate from the trough in a few days and turn southeastward, and there are still large differences on exactly when that will occur. The deterministic runs of the GFS and ECMWF have come into better agreement on the future track of Leslie, but the ensembles of those models indicate that the range of possible tracks hasn't actually decreased. Confidence in the track forecast therefore remains quite low. In general, the guidance suite has shifted to the south and west, particularly between 36 and 96 h. The official track forecast has been shifted in that direction to bring it closer to the track consensus. However, it should be emphasized that confidence in the track forecast remains low at this time. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 35.9N 49.9W 50 KT 60 MPH 12H 08/0600Z 35.4N 48.2W 50 KT 60 MPH 24H 08/1800Z 34.3N 45.7W 50 KT 60 MPH 36H 09/0600Z 32.8N 43.2W 55 KT 65 MPH 48H 09/1800Z 31.2N 41.3W 55 KT 65 MPH 72H 10/1800Z 28.2N 38.8W 60 KT 70 MPH 96H 11/1800Z 28.6N 33.0W 65 KT 75 MPH 120H 12/1800Z 30.5N 27.0W 60 KT 70 MPH $$ Forecaster Zelinsky
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