ZCZC MIATCDAT5 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NICOLE DISCUSSION NUMBER 17 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 500 AM AST SAT OCT 08 2016 Nicole's structure has changed dramatically just within the past six hours due to about 45 kt of northerly shear. The deep convection is now oriented linearly from east to west and is displaced more than 100 n mi to the south of the exposed low-level center. Dvorak Current Intensity numbers have dropped to 3.0 from TAFB, SAB, and the UW-CIMSS ADT, and Nicole's initial intensity is lowered to 45 kt. Deep-layer northerly flow continues to push Nicole southward, and the initial motion is estimated to be 190/6 kt. The winds on the west side of a mid-level low should continue forcing Nicole generally southward for the next 24-36 hours until these two systems become collocated with one another. After 36 hours, Nicole is expected to be steered back toward the north, ahead of Hurricane Matthew's remnant mid-level circulation. There are some differences among the track models associated with exactly how the interaction between Nicole and Matthew will play out. The notable outlier is the ECMWF model, which swings Nicole northwestward and then westward around the north side of Matthew after 48 hours. In deference to this model, the new NHC track forecast is a little west and slower than the previous forecast, and it lies very close to an average of the GFS and ECMWF models. The vertical shear affecting Nicole is expected to remain high for several more days, possibly not dropping below 20 kt until after 72 hours. Still, sea surface temperatures will remain between 29 and 30C, so Nicole may be able to continue producing bursts of deep convection that will prevent its intensity from decreasing much. Some restrengthening at the end of the forecast period is possible, although trends are suggesting that the shear may once again increase by day 5. Based on the latest guidance, the official intensity forecast is lowered by 5 kt for much of the forecast period. If the shear wins out, however, then Nicole's intensity could end up being lower than shown in the forecast. FORECAST POSITIONS AND MAX WINDS INIT 08/0900Z 25.9N 65.6W 45 KT 50 MPH 12H 08/1800Z 25.2N 65.6W 45 KT 50 MPH 24H 09/0600Z 24.7N 65.6W 40 KT 45 MPH 36H 09/1800Z 24.8N 65.7W 40 KT 45 MPH 48H 10/0600Z 25.4N 65.9W 40 KT 45 MPH 72H 11/0600Z 28.0N 66.5W 40 KT 45 MPH 96H 12/0600Z 30.0N 67.5W 45 KT 50 MPH 120H 13/0600Z 32.5N 66.0W 50 KT 60 MPH $$ Forecaster Berg NNNN