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Tropical Storm ARTHUR Forecast Discussion Number 9
2014-07-03 04:55:58| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT WED JUL 02 2014 000 WTNT41 KNHC 030255 TCDAT1 TROPICAL STORM ARTHUR DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014 1100 PM EDT WED JUL 02 2014 Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft, along with satellite data, indicate that Arthur is very near hurricane strength. On one side, the central pressure has fallen to 988 mb, there were a few estimates of hurricane force winds from the SFMR instrument on the Air Force plane, and there are several satellite intensity estimates of 65-75 kt. On the other side, the flight-level winds from the two aircraft did not support hurricane strength, and the SFMR winds from the NOAA plane were also below hurricane strength. Given the conflicting data, the initial intensity is held at 60 kt. Another aircraft is scheduled to investigate Arthur around 06Z. The initial motion is now 360/7. Arthur is moving through a weakness in the subtropical ridge towards the westerlies over the eastern United States. During the next 24-36 hours, the cyclone should recurve northeastward ahead of a deep-layer baroclinic trough moving eastward through the Great Lakes and New England. While the guidance is in good agreement with this scenario, the center of the guidance envelope has again shifted a little westward toward the North Carolina coast. The GFS has made a rather significant shift since the previous run, and it now brings the center of Arthur across eastern North Carolina. The new forecast track is shifted a little closer to the coast, but it will stay in the center of the guidance envelope to the east of the GFS. Coastal radar data shows that Arthur is having trouble maintaining a closed eyewall, which is likely due to continued entrainment of dry air. However, the storm should remain in an area of light vertical wind shear and over warm sea surface temperatures for the next 36 hours or so. Thus, the new intensity forecast calls for additional strengthening during that time similar to the previous forecast. After 48 hours, Arthur should merge with the baroclinic trough over the Canadian Maritimes and become extratropical. The intensities and wind radii during the extratropical phase have been modified based on input from the Ocean Prediction Center. 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 03/0300Z 30.6N 79.1W 60 KT 70 MPH 12H 03/1200Z 31.7N 78.9W 65 KT 75 MPH 24H 04/0000Z 33.5N 77.4W 70 KT 80 MPH 36H 04/1200Z 36.0N 74.5W 75 KT 85 MPH 48H 05/0000Z 39.0N 70.7W 75 KT 85 MPH 72H 06/0000Z 45.5N 63.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 07/0000Z 51.0N 55.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 08/0000Z 55.5N 50.5W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven
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