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| #803446 (Received by flhurricane at: 10:40 PM 24.Sep.2015) TCDAT5 TROPICAL DEPRESSION IDA DISCUSSION NUMBER 27 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102015 1100 PM AST THU SEP 24 2015 The center of Ida, like most of the Atlantic tropical cyclones this year at some point, is exposed to southwest of a bursting area of deep convection. The initial intensity is kept at 30 kt in accordance with the latest TAFB Dvorak classification. A combination of shear and dry air aloft is expected to persist near Ida for the next few days. These conditions are forecast to cause the cyclone to gradually weaken. Although the cyclone could move into a slightly more favorable environment at long range, there isn't likely to be much left of Ida to take advantage of the conditions. The latest NHC forecast is close to the model consensus for the first few days, then is below that aid at days 3 and 4, leaning more heavily on the weaker solutions of the HWRF, GFS and ECMWF models. Both the GFS and the ECMWF now show Ida opening up into a trough by day 5, and the official forecast follows that trend. Ida is moving erratically north-northwestward at about 4 knots. The depression should turn northwestward tomorrow and head in that general direction for a couple of days due to a weak subtropical ridge forming over the central Atlantic. After that time, the cyclone is expected to be a shallow system, and will likely move to the west or west-southwest as it is steered by a strong low-level ridge. The guidance has shifted leftward, which makes sense for a weaker cyclone, and the official NHC prediction follows suit. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 21.3N 45.3W 30 KT 35 MPH 12H 25/1200Z 21.9N 45.6W 30 KT 35 MPH 24H 26/0000Z 22.8N 46.3W 25 KT 30 MPH 36H 26/1200Z 23.7N 47.2W 25 KT 30 MPH 48H 27/0000Z 24.4N 48.0W 25 KT 30 MPH 72H 28/0000Z 24.3N 49.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 29/0000Z 24.0N 51.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 30/0000Z...DISSIPATED $$ Forecaster Blake |
