ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM HURRICANE ARTHUR DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014 500 PM EDT THU JUL 03 2014 The eye of Arthur has become more distinct in visible satellite imagery this afternoon, although the overall radar presentation has changed very little. The latest flight-level and SFMR wind observations are 84 kt and 82 kt respectively. These data support maintaining the 80-kt initial intensity. Environmental conditions are expected to remain conducive for strengthening during the next 12 to 18 hours and Arthur is still forecast to reach category two intensity as it nears the North Carolina coast. Vertical shear is forecast to increase significantly by Friday night and weakening should commence by that time. Arthur is expected to interact with an approaching deep-layer trough and should become a post-tropical cyclone within 48 hours. Steady weakening is anticipated after Arthur becomes post-tropical. Aircraft and radar fixes indicate that the initial motion is 020 degrees at 11 kt, a little faster than before. Arthur is expected to turn northeastward and accelerate ahead of a deep-layer trough that will move into the eastern United States during the next day or so. Although the models still remain in good agreement on the track of Arthur during the next couple of days, there has been a westward shift this cycle. The new NHC track has been shifted westward and lies between the GFS and ECMWF models through 36 hours. The updated track now shows landfall in eastern North Carolina or the Outer Banks later tonight. Beyond 36 hours, the NHC track has been adjusted about a degree westward, but it is not as far west as the GFS and ECMWF model trackers. While in most cases this westward shift in the track will be immaterial to impacts, it does mean that the hurricane's strongest winds are now more likely to be experienced along the Outer Banks, rather than remain offshore. NHC public advisories will be issued every two hours beginning at 7 pm EDT this evening and Tropical Cyclone Updates will be issued on the hour between each Public Advisory to provide hourly position updates. The new experimental potential storm surge flooding map is available at: http://www.nhc.noaa.gov/graphics_at1.shtml?inundation FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 33.4N 77.9W 80 KT 90 MPH 12H 04/0600Z 35.3N 76.1W 85 KT 100 MPH 24H 04/1800Z 38.2N 72.6W 85 KT 100 MPH 36H 05/0600Z 41.9N 68.0W 75 KT 85 MPH 48H 05/1800Z 45.2N 64.2W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 06/1800Z 50.4N 56.2W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 07/1800Z 56.5N 47.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 08/1800Z 60.0N 37.5W 30 KT 35 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown NNNN