000 WTNT44 KNHC 070257 TCDAT4
HURRICANE MATTHEW DISCUSSION NUMBER 36 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 PM EDT THU OCT 06 2016
The satellite appearance of Matthew has improved during the past several hours, with an eye embedded within a more circular central dense overcast and an increase in the outer banding. Reports from a NOAA Hurricane Hunter aircraft and coastal radar data show the presence of centric eyewalls with diameters of about 8 and 60 n mi respectively. The NOAA aircraft earlier reported a minimum pressure of 937 mb, and an Air Force Reserve Hurricane Hunter just reported estimated surface winds of 109 kt from the SFMR and a pressure of 939 mb. Based on these data, the initial intensity is 115 kt.
The initial motion is 325/11 kt. For the next 24-48 hours, Matthew should move around the western end of the subtropical ridge, with the motion gradually turning northward and then northeastward. During this time, the center of the guidance envelope and the various consensus models have shifted a little to the east. However, the ECMWF, GFS, and UKMET continue to suggest the possibility of the hurricane making landfall in Florida and then moving near the coasts of Georgia and South Carolina. This part of the forecast is nudged a little to the east and lies between the model consensus and the previous forecast. After 48 hours, a mid- to upper-level ridge is forecast to build north and west of Matthew, and the track guidance forecasts a southeasterly to southerly motion in response. While there is still a large spread, the GFS, ECMWF, and UKMET are in better agreement that Matthew should move south between the ridge and Hurricane Nicole to the east. This part of the forecast follows this guidance and lies between the GFS and ECMWF.
During the next 12-24 hours, Matthew will likely weaken a little as it undergoes an eyewall replacement cycle. After that time, it is expected to encounter strong southwesterly vertical shear, and later in the forecast period dry air is likely to entrain into the cyclone. This combination should cause steady weakening, and Matthew is forecast to drop below hurricane strength by 72 hours. The new intensity forecast is in best agreement with the SHIPS model.
1. Matthew is likely to produce devastating impacts from storm surge, extreme winds, and heavy rains in the northwestern Bahamas today, and along extensive portions of the east coast of Florida tonight.
2. Evacuations are not just a coastal event. Strong winds will occur well inland from the coast, and residents of mobile homes under evacuation orders are urged to heed those orders.
3. Hurricane winds increase very rapidly with height, and residents of high-rise buildings are at particular risk of strong winds. Winds at the top of a 30-story building will average one Saffir-Simpson category higher than the winds near the surface.
4. 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 specify impacts at any one location. Only a small deviation of the track to the left of the NHC forecast could bring the core of a major hurricane onshore within the hurricane warning area in Florida and Georgia. Modest deviations to the right could keep much of the hurricane-force winds offshore. Similarly large variations in impacts are possible in the hurricane watch and warning areas in northeast Georgia and South Carolina.
5. The National Hurricane Center is issuing Potential Storm Surge Flooding Maps, and Prototype Storm Surge Watch/Warning Graphics for Matthew. It is important to remember that the Potential Storm Surge Flooding Map does not represent a forecast of expected inundation, but rather depicts a reasonable worst-case scenario -- the amount of inundation that has a 10 percent chance of being exceeded.
FORECAST POSITIONS AND MAX WINDS
INIT 07/0300Z 27.1N 79.2W 115 KT 130 MPH 12H 07/1200Z 28.5N 80.2W 110 KT 125 MPH 24H 08/0000Z 30.3N 80.8W 105 KT 120 MPH 36H 08/1200Z 31.8N 80.2W 90 KT 105 MPH 48H 09/0000Z 32.6N 78.7W 75 KT 85 MPH 72H 10/0000Z 31.5N 75.5W 60 KT 70 MPH 96H 11/0000Z 29.0N 75.5W 50 KT 60 MPH
120H 12/0000Z 27.0N 77.0W 40 KT 45 MPH
$$ Forecaster Beven