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| #803592 (Received by flhurricane at: 4:55 PM 29.Sep.2015) TCDAT1 TROPICAL STORM JOAQUIN DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 500 PM EDT TUE SEP 29 2015 The cloud pattern of the storm has become better organized during the day, with the low level center now embedded inside the northern edge of the main area of deep convection. Animation of cirrus motions suggest that upper-level outflow is becoming a little more prominent over the northern portion of the circulation, and this is consistent with decreasing northerly shear. Flight-level, dropsonde, and SFMR wind observations from an Air Force reconnaissance aircraft indicate that Joaquin has strengthened and the intensity is now estimated to be 55 kt. With a more favorable upper-level wind environment now expected to prevail, the official forecast calls for more strengthening than the previous advisories. Joaquin is expected to become a hurricane within 24 hours, with additional intensification likely thereafter. The NHC intensity forecast is similar to the latest SHIPS model output. Fixes from the aircraft show a southward component of motion and the initial motion estimate is now 240/4 kt. Joaquin is currently south of the southwestern periphery of a weak mid-level ridge. The ECMWF model shows this ridging to the north of the tropical cyclone to be more prominent over the next few days than the other dynamical models. Consequently, the ECMWF takes Joaquin more to the west and southwest through 72 hours than any of the other available guidance. Later in the forecast period, there is a significant divergence in the track guidance. The HWRF and U.K. Met Office models forecast Joaquin to move over the east coast of the United States later in the period whereas the ECMWF and GFS keep the system well offshore. The official forecast lies between these possibilities and is similar to the latest Florida State University Superensemble solution. Interests in the Bahamas should monitor the progress of this storm. Watches or warnings may be issued for portions of these islands later this evening. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 26.0N 71.0W 55 KT 65 MPH 12H 30/0600Z 25.8N 71.6W 60 KT 70 MPH 24H 30/1800Z 25.5N 72.5W 65 KT 75 MPH 36H 01/0600Z 25.1N 73.3W 70 KT 80 MPH 48H 01/1800Z 24.8N 73.9W 75 KT 85 MPH 72H 02/1800Z 25.0N 74.0W 80 KT 90 MPH 96H 03/1800Z 29.0N 73.0W 80 KT 90 MPH 120H 04/1800Z 34.0N 71.0W 75 KT 85 MPH $$ Forecaster Pasch |
