000 WTPZ44 KNHC 282054 TCDEP4 Hurricane Nora Discussion Number 13 NWS National Hurricane Center Miami FL EP142021 400 PM CDT Sat Aug 28 2021 Nora developed a cloud-filled eye during the past few hours, with the center now grazing the coast and the eyewall moving across western Jalisco, Mexico. An Air Force Reserve Hurricane Hunter aircraft has been investigating the hurricane, but unfortunately the storm is now too close to the mountainous coastline for the plane to safely locate the surface center or sample the likely-stronger wind field on the eastern side of the circulation. Based mainly on T4.5/77 kt Dvorak estimates from TAFB and SAB, the initial intensity is estimated to be 75 kt. The center has been moving a little faster to the west of due north, or 350/12 kt. The track models are in agreement that Nora should turn toward the north-northwest and northwest during the next few days, generally keeping the center of the hurricane over the waters of the Gulf of California. However, due to the complex geography and mountainous topography of the region, the track forecast is challenging, and it's almost impossible to know if Nora's center will remain over water or graze the coastlines of Nayarit and Sinaloa over the next few days. By days 4 and 5, Nora's center is forecast to move inland over Sonora after traversing a significant length of the Gulf of California. Assuming a path that keeps Nora just offshore, low shear and very warm sea surface temperatures in the Gulf of California should be sufficient to at least maintain hurricane intensity for the next 3 days. However, any slight deviations of the track could cause Nora to weaken and fall below hurricane intensity sooner than is indicated in the official forecast. Given the uncertainties, however, the government of Mexico has extended the hurricane warning farther north along the coasts of Nayarit and Sinaloa out of an abundance of caution. Weakening will become more likely the farther north Nora gets up the Gulf of California, both due to possible land interaction and ingestion of drier air off the Mexican plateau. Key Messages: 1. Nora is forecast to be a hurricane while it moves near or along the coasts of the Mexican states of Jalisco, Nayarit, and Sinaloa through Monday, 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 Mexican states of Guerrero, 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 28/2100Z 19.7N 105.4W 75 KT 85 MPH...ON THE COAST 12H 29/0600Z 21.5N 105.9W 75 KT 85 MPH 24H 29/1800Z 22.9N 106.7W 75 KT 85 MPH 36H 30/0600Z 23.5N 107.4W 75 KT 85 MPH 48H 30/1800Z 24.2N 108.1W 75 KT 85 MPH 60H 31/0600Z 24.8N 108.9W 70 KT 80 MPH 72H 31/1800Z 25.6N 109.5W 70 KT 80 MPH 96H 01/1800Z 27.6N 110.4W 55 KT 65 MPH...INLAND 120H 02/1800Z 29.4N 110.6W 30 KT 35 MPH...INLAND $$ Forecaster Berg