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Tropical Storm KIRK
ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM Tropical Storm Kirk Discussion Number 1 NWS National Hurricane Center Miami FL AL122018 1100 AM AST Sat Sep 22 2018 The area of low pressure located well south of the Cabo Verde Islands now has a well-defined center and enough organized deep convection to be considered a tropical cyclone. The initial intensity is set to 35 kt based on data from recent ASCAT passes that showed an area of 30-35 kt winds northwest of the center. Kirk will be moving over SSTs around 27C for the next 36 hours or so with generally low shear, which should allow for some gradual strengthening. After that time, the SSTs increase quickly along the forecast track, but the SHIPS model and global model fields show the vertical shear increasing, in part due to the very fast low-level easterly flow. In addition, the GFS and ECMWF global models don't show much development of the cyclone during the forecast period. As a result of these factors, little change in strength is forecast after 48 hours. The NHC forecast is close to the HCCA consensus aid through 48 hours and is near IVCN afterward. The initial motion estimate is 280/12, but has the usual uncertainty for a system in the early stages of development. The cyclone is expected to be steered very quickly westward at low latitudes with forward speeds reaching 20-25 kt over the next 72 hours to the south of a mid-level ridge. Late in the period, some gain in latitude and a slight decrease in forward speed are shown as a weakness in the ridge develops to the east of the Lesser Antilles. The initial NHC track forecast is close to HCCA and a little south of the TVCA consensus, giving a little more weight to the GFS and ECMWF, which lie on the south side of the track guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 22/1500Z 8.3N 23.6W 35 KT 40 MPH 12H 23/0000Z 8.8N 25.7W 40 KT 45 MPH 24H 23/1200Z 9.3N 29.6W 45 KT 50 MPH 36H 24/0000Z 9.4N 34.0W 50 KT 60 MPH 48H 24/1200Z 9.6N 38.6W 50 KT 60 MPH 72H 25/1200Z 10.3N 46.8W 50 KT 60 MPH 96H 26/1200Z 11.0N 53.0W 50 KT 60 MPH 120H 27/1200Z 12.5N 58.5W 45 KT 50 MPH $$ Forecaster Brennan NNNN