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| #872680 (Received by flhurricane at: 4:44 AM 22.Aug.2016) TCDAT1 TROPICAL DEPRESSION FIONA DISCUSSION NUMBER 22 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016 500 AM AST MON AUG 22 2016 Although deep convection has continued to pulse near the center of Fiona, recent scatterometer wind data and various satellite classifications support maintaining the small but remarkably resilient cyclone as a 30-kt tropical depression. The intensity forecast still remains something of an enigma. Strong westerly wind shear is forecast to persist for the next 12-18 hours, after which the upper-level winds relax somewhat and become a little more conducive for strengthening to occur. However, dry mid-level air of 40-50 percent humidity is also forecast to surround the cyclone, which could act to hinder the development of persistent deep convection for the next 24-36 hours. Therefore, if Fiona can survive the aforementioned hostile conditions during the next 24 hours or so, then some restrengthening or maintaining the status as a tropical cyclone is possible. The global models still disagree on the future of Fiona and have flipped-flopped, with the ECMWF no longer showing dissipation in 5 days, which is similar to the UKMET solution, whereas the GFS now shows Fiona degenerating into an open trough between 96-120 hours. The NHC forecast maintains continuity and indicates dissipation in 5 days as a compromise between these possibilities. The initial motion estimate remains 290/16 kt. Although there is uncertainty in the future status of Fiona, the NHC model guidance is in pretty good agreement on the track of the cyclone for the next 72 hours. The small cyclone is forecast to move quickly west-northwestward around the southwestern periphery of a deep-layer ridge for the next 3 days, and then slow down considerably on day 4 and turn northward into a weakness in the ridge. The new official forecast track is basically just an update of the previous track through 72 hours, and then is a little to the right of the previous forecast on day 4, which leans closer to the solutions of the various consensus models. FORECAST POSITIONS AND MAX WINDS INIT 22/0900Z 24.4N 58.4W 30 KT 35 MPH 12H 22/1800Z 25.0N 60.2W 30 KT 35 MPH 24H 23/0600Z 25.8N 62.3W 30 KT 35 MPH 36H 23/1800Z 26.6N 64.1W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 24/0600Z 27.6N 65.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 25/0600Z 29.8N 67.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 26/0600Z 31.3N 67.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 27/0600Z...DISSIPATED $$ Forecaster Stewart |
