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Hurricane ARTHUR Forecast Discussion Number 15
2014-07-04 16:42:27| National Hurricane Center (Atlantic)
Issued at 1100 AM EDT FRI JUL 04 2014 000 WTNT41 KNHC 041442 TCDAT1 HURRICANE ARTHUR DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014 1100 AM EDT FRI JUL 04 2014 The eye of Arthur remains evident in geostationary satellite imagery although the cloud tops surrounding the eye have warmed this morning. The U.S. Air Force Reserve Hurricane Hunter aircraft has measured 94-kt 700 mb flight-level winds in the southeastern quadrant, but it appears that these winds are not effectively mixing down to the surface, as peak SFMR surface winds have been 68 kt. Using a blend of the these data, the initial intensity has been reduced to 80 kt. Arthur will be moving over cooler water and the shear will be significantly increasing through tonight, which should cause gradual weakening. The hurricane will also interact with a deep-layer trough and associated cold front that will be moving off the United States east coast later today. This should cause the hurricane to complete transition into an extratropical cyclone in about 24 hours. After that time, continued weakening is expected while the post-tropical cyclone moves over the North Atlantic. Arthur is moving northeastward with an initial motion of 040/21 kt. The hurricane should continue moving northeastward during the next 24 to 36 hours ahead of the aforementioned deep-layer trough. The center of the cyclone is forecast to move over Nova Scotia on Saturday and track models are in good agreement on this portion of the forecast. The track guidance become very divergent after 48 hours, with the ECMWF taking the cyclone northward and northwestward while the GFS shows an east-northeastward motion near Newfoundland. Out of continuity for the previous forecasts, the NHC track continues to follow the eastward scenario shown by the GFS and GFS ensemble mean, but it now shows a somewhat slower motion by day 5. It is possible that this portion of the track will need to be adjusted in future forecasts. Hourly position updates and two-hourly intermediate advisories have been discontinued. Three-hourly intermediate advisories will continue as long as coastal warnings remain in effect. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 37.7N 73.4W 80 KT 90 MPH 12H 05/0000Z 40.2N 70.1W 75 KT 85 MPH 24H 05/1200Z 44.0N 66.1W 60 KT 70 MPH...POST-TROP/EXTRATROP 36H 06/0000Z 46.1N 63.2W 55 KT 65 MPH...POST-TROP/EXTRATROP 48H 06/1200Z 48.0N 59.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 07/1200Z 55.0N 52.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 08/1200Z 59.0N 46.0W 30 KT 35 MPH...POST-TROP/EXTRATROP 120H 09/1200Z 62.0N 35.0W 30 KT 35 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown
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