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Hurricane Nora Forecast Discussion Number 14
2021-08-29 04:59:24| National Hurricane Center (East Pacific)
Issued at 1000 PM CDT Sat Aug 28 2021 000 WTPZ44 KNHC 290259 TCDEP4 Hurricane Nora Discussion Number 14 NWS National Hurricane Center Miami FL EP142021 1000 PM CDT Sat Aug 28 2021 Surface data from Mexico, data from an Air Force Reserve Hurricane Hunter aircraft, and microwave imagery from an 2344 UTC SSMIS indicate that the center of Nora moved over the far northwestern coast of Jalisco earlier this evening. Since then, the cloud pattern of the hurricane has degraded, but not enough to bring the latest Dvorak estimates below hurricane strength. The advisory intensity is therefore set at 65 kt based on the assumption that interaction with land has caused weakening, however there is low confidence in this assessment. The ever-so-slight rightward deviation from the forecast track that brought Nora inland, at least briefly, highlights the sensitivity of the system's future to its exact track. A sizable portion of the latest dynamical guidance, including the GFS, ECMWF, and HWRF models indicate that Nora will move inland tonight or early Sunday and dissipate. All three models also indicate it could reform over the Gulf of California in a few days. Other models, like the UKMET and CMC global models maintain Nora as a coherent tropical cyclone much longer. While the models can easily flip flop from run to run, the NHC forecast cannot drastically change solutions so cavalierly. Therefore, the official forecast is based on the condition that Nora will stay far enough offshore to persist as a tropical cyclone. Regardless of its exact state, Nora is forecast to turn toward the northwest on Sunday and then move along the coast toward northern Mexico early next week. This general solution is supported by all of the available guidance. A slight eastward adjustment has been made to the NHC track forecast to account for the slightly east initial position. Given Nora's recent movement over land, the intensity forecast has been lowered substantially at all forecast hours, but still maintains Nora near hurricane strength for the next couple of days. This is well above the most recent intensity consensus, which is heavily influenced by the dynamical models that move Nora inland. If it doesn't move inland sooner, Nora will likely quickly weaken as it moves permanently inland by around 96 h, and become a remnant low by the end of the forecast period. Key Messages: 1. Nora is forecast to be at or near hurricane strength while it moves near the coasts of Nayarit and Sinaloa through the weekend, and hurricane warnings are in effect for portions of that coastline. Interests in these areas should closely monitor the progress of Nora and subsequent updates to the forecast. 2. Heavy rain associated with Nora is expected across the west coast of Mexico from the states of Michoacan northward to southern Sonora, including Baja California Sur. This rain will likely result in life-threatening flash flooding and mudslides across these regions. Rainfall from Nora may spread into the southwestern U.S. and central Rockies during the middle to latter portion of next week. 3. Nora is forecast to continue moving northward over the Gulf of California Tuesday and Wednesday, bringing a risk of wind impacts to portions of the Mexican states of Baja California Sur, northern Sinaloa, and Sonora. Given the above-average uncertainty in the forecast intensity, confidence is not high enough to determine the magnitude and location of these potential impacts. FORECAST POSITIONS AND MAX WINDS INIT 29/0300Z 21.3N 105.5W 65 KT 75 MPH 12H 29/1200Z 22.8N 106.2W 65 KT 75 MPH 24H 30/0000Z 23.7N 107.1W 60 KT 70 MPH 36H 30/1200Z 24.4N 107.9W 60 KT 70 MPH 48H 31/0000Z 24.9N 108.6W 60 KT 70 MPH 60H 31/1200Z 25.6N 109.4W 55 KT 65 MPH 72H 01/0000Z 26.8N 110.1W 55 KT 65 MPH 96H 02/0000Z 28.6N 110.7W 35 KT 40 MPH...INLAND 120H 03/0000Z 30.2N 110.9W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster D. Zelinsky
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