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Tropical Storm Leslie Forecast Discussion Number 41
2018-10-06 16:59:03| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sat Oct 06 2018 000 WTNT43 KNHC 061458 TCDAT3 Tropical Storm Leslie Discussion Number 41 NWS National Hurricane Center Miami FL AL132018 1100 AM AST Sat Oct 06 2018 The central convection associated with Leslie has become better organized this morning, with conventional satellite imagery showing a tightly curved band and recent microwave imagery showing a mid-level eye. However, the microwave data also suggests the mid-level eye is located to the southeast of the low-level center. It is also not known whether there is an inner wind maximum associated with this feature. Satellite intensity estimates are mostly in the 45-55 kt range, so the initial intensity remains 50 kt. The initial motion is now 080/8. Leslie is now in or near the southern edge of the mid-latitude westerlies, and with the assistance of a couple of shortwave troughs, these are expected to push Leslie toward the east and southeast throughout the forecast period. Despite general agreement on the synoptic pattern, there is now a large spread in the guidance toward the end of the forecast period. The ECMWF and UKMET show a more southward turn after 72 h, taking Leslie well south of 30N. The GFS, on the other hand, shows a more eastward motion to the point where by 96 h it is 950 n mi from the UKMET forecast position. The new forecast track compromises between these extremes and lies near the TVCN consensus, with the caveat that the part after 72 h is of low confidence. Leslie should weaken some during the next 48 h or so as it crosses an area of cooler sea surface temperatures. After that, the track takes the center back over warmer water at the same time when there may be an increase in shear. There is an increased uncertainty in the intensity forecast caused by the track forecast uncertainties. If Leslie moves closer to the GFS track, it will be over cooler water and in stronger shear, while if it moves closer to the UKMET solution it will be over warmer water and lighter shear. Due to to the uncertainty, only minor adjustments are made to the previous intensity forecast. Additional adjustments may be needed later depending on changes in the track forecast. Large swells generated by Leslie are expected to continue during the next few days across the northeastern coast of the United States, Bermuda, the Greater and Lesser Antilles, and Atlantic Canada. 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 06/1500Z 37.7N 55.8W 50 KT 60 MPH 12H 07/0000Z 37.6N 54.1W 50 KT 60 MPH 24H 07/1200Z 37.3N 51.5W 45 KT 50 MPH 36H 08/0000Z 36.6N 49.0W 45 KT 50 MPH 48H 08/1200Z 35.7N 46.5W 40 KT 45 MPH 72H 09/1200Z 33.0N 41.5W 45 KT 50 MPH 96H 10/1200Z 30.0N 37.0W 50 KT 60 MPH 120H 11/1200Z 29.0N 31.0W 50 KT 60 MPH $$ Forecaster Beven
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