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Tropical Depression Eight Forecast Discussion Number 1
2017-08-13 04:48:22| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Sat Aug 12 2017 000 WTNT43 KNHC 130248 TCDAT3 Tropical Depression Eight Discussion Number 1 NWS National Hurricane Center Miami FL AL082017 1100 PM EDT Sat Aug 12 2017 Late afternoon GOES-16 visible satellite images showed that the circulation associated with the low pressure located northeast of the Bahamas had become better defined. Since that time, the night-time microphysics RGB product and other infrared satellite pictures have continued to show an improvement in the circulation, and recent ASCAT data show that the system has acquired a well- defined center. Deep convection is organized in a large curved band, however the center is located near the western edge of the band. NOAA buoy 41046 located southeast of the center reported 25 to 30 kt winds earlier this evening, and the scatterometer data support an initial wind speed of 30 kt. The depression is moving north-northwestward or 330/11 kt. The depression should move north-northwestward to northward around the western side of a deep-layer ridge over the central Atlantic through Sunday night. It is expected to reach the mid-latitude westerlies by late Monday and begin to accelerate northeastward ahead of a short-wave trough that will be approaching the northeastern United States. The steering currents are well established over the western Atlantic and the track guidance is in good agreement on the forecast scenario. The NHC track forecast lies near the various consensus aids. The intensity forecast is more problematic. The system is expected to traverse warm water and remain in a low-shear environment during the next day or so, but intrusions of dry mid-level air are likely to limit strengthening. The statistical guidance and the HWRF favor more significant intensification than the global models, which generally do not show much deepening. In deference to the global models, the NHC forecast is below the consensus, especially later in the period. The system is likely to become extratropical in 3 to 4 days, and the extratropical portion of the forecast is based on guidance provided by the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 25.3N 70.3W 30 KT 35 MPH 12H 13/1200Z 27.0N 71.2W 35 KT 40 MPH 24H 14/0000Z 29.0N 71.9W 40 KT 45 MPH 36H 14/1200Z 30.7N 72.0W 45 KT 50 MPH 48H 15/0000Z 32.2N 71.4W 50 KT 60 MPH 72H 16/0000Z 36.2N 66.9W 55 KT 65 MPH 96H 17/0000Z 41.5N 54.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 18/0000Z 45.5N 39.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown
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