000 WTNT44 KNHC 050256 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 PM EDT TUE OCT 04 2016 Hurricane Matthew made landfall along the extreme eastern coast of Cuba near Juaco around 0000 UTC this evening, and the eye is just now moving off of the northeastern coast of Cuba. Some weakening has occurred due to interaction with the mountains of eastern Cuba and western Haiti. However, latest reports from an Air Force Reserve reconnaissance aircraft indicate that the central pressure hasn't risen much and that the maximum winds have only decreased to an estimated 115 kt, keeping Matthew a dangerous category four hurricane. Radar and recon fixes indicate that Matthew is moving slightly west of due north, or 350/07 kt. Matthew is expected to begin turning toward the north-northwest during the next 12 hours or so, followed by a northwestward motion in 24-48 hours as the large ridge to the north of the powerful hurricane begins to build westward across the southeastern United States in response to a broad trough over the central U.S. weakening and lifting out to the northeast. The next upstream weather system that will affect the steering currents surrrounding Matthew is a large trough currently approaching the northwestern U.S. and southwestern Canada. That system is forecast to dig southeastward and amplify over the central U.S. during next several days, resulting in significant ridging downstream over the northeastern United States. As the next ridge builds and lifts northward, Matthew is expected to turn northward as well by 72 hours, and turn northeastward after that as the aforementioned trough moves eastward into the eastern United States by 96-120 hours. The official forecast track remains close to a blend of the GFS and ECMWF models. The current 10-15 kt of northwesterly vertical wind shear is forecast to weaken to around 5 kt by 36-48 hours while Matthew is moving over the warm waters of the Gulf Stream, where SSTs are expected to be near 30 deg C. That combination, along with high mid-level humidity, should enable Matthew to maintain category four status, although eyewall replacement cycles, which can not be forecast with any skill, could result in fluctuations in the intensity not shown by the official forecast. By 72 hours and beyond, steadily increasing vertical wind shear is expected to induce gradual weakening. The official intensity forecast is close to but slightly above the consensus model IVCN. KEY MESSAGES: 1. Matthew is likely to produce devastating impacts from storm surge, extreme winds, heavy rains, flash floods, and/or mudslides in portions of the warning areas in Haiti, Cuba, and the Bahamas. Please consult statements from the meteorological services and other government officials in those countries. 2. When a hurricane is forecast to take a track roughly parallel to a coastline, as Matthew is forecast to do from Florida through South Carolina, it becomes very difficult to estimate impacts this far in advance. For example, only a small deviation of the track to the left of the NHC forecast could bring the core of a major hurricane onshore, while a small deviation to the right could keep all of the hurricane-force winds offshore. It will likely take another day or so for the potential impacts of Matthew in the United States to clarify. 3. Tropical storm or hurricane conditions could affect portions of Florida north of the current Hurricane Watch area, Georgia, South Carolina, and North Carolina later this week or this weekend, even if the center of Matthew remains offshore. It is too soon to specify what, if any, direct impacts Matthew might have on the remainder of the U.S. east coast farther to the north. At a minimum, very dangerous beach and boating conditions are likely along much of the U.S. east coast later this week and weekend. FORECAST POSITIONS AND MAX WINDS INIT 05/0300Z 20.4N 74.4W 115 KT 130 MPH 12H 05/1200Z 21.7N 74.8W 115 KT 130 MPH 24H 06/0000Z 23.3N 76.0W 115 KT 130 MPH 36H 06/1200Z 25.0N 77.6W 115 KT 130 MPH 48H 07/0000Z 26.7N 79.0W 115 KT 130 MPH 72H 08/0000Z 30.3N 80.8W 100 KT 115 MPH 96H 09/0000Z 33.2N 78.1W 85 KT 100 MPH 120H 10/0000Z 37.0N 72.0W 70 KT 80 MPH $$ Forecaster Stewart