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HURRICANE ARTHUR DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012014
500 AM EDT THU JUL 03 2014

Data from NOAA and Air Force Reserve Hurricane Hunter aircraft
indicate that Arthur has reached hurricane strength. Both aircraft
showed several SFMR winds of 60 to 63 kt southeast of the center,
and the NOAA aircraft reported a peak flight-level wind of 79 kt at
8,000 feet. Based on these data the initial intensity is set to 65
kt. Radar data show that Arthur was still having difficulty
maintaining an eyewall overnight, likely due to dry mid/upper-level
air being entrained into the storm. However, the overall radar
presentation has improved during the past couple of hours. Some
gradual intensification is forecast during the next 24 hours while
the cyclone is in an environment of low shear and moves over warm
waters. After that time, however, the shear increases dramatically
as Arthur interacts with a deep-layer baroclinic zone moving off
of the east coast of North America, and global model fields show
Arthur completing extratropical transition by 72 hours. The NHC
intensity forecast is similar to the previous one and remains close
to the multi-model consensus IVCN through 24 hours and is a little
below the consensus after that time.

Radar data and aircraft fixes indicate that the current motion is
now a little east of due north, or 010 degrees at 8 knots. Arthur
should begin to recurve today ahead of the aforementioned deep-layer
trough, and the track model guidance is in good agreement on this
scenario. The NHC track forecast is similar to the previous one and
remains near the middle of the dynamical model envelope and close
to the TVCA multi-model consensus. The official forecast shows the
center of Arthur moving very close to the North Carolina Outer Banks
late tonight and early Friday. Arthur should then accelerate
northeastward offshore of the mid-Atlantic states and the
northeastern U.S. Friday and Friday night, and move into the
Canadian Maritimes by Saturday before turning northward by the end
of the period.

The track, intensity, and wind radii forecast during the
extratropical phase of Arthur have been coordinated with 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  03/0900Z 31.3N  79.1W   65 KT  75 MPH
 12H  03/1800Z 32.5N  78.3W   70 KT  80 MPH
 24H  04/0600Z 34.7N  76.1W   75 KT  85 MPH
 36H  04/1800Z 37.5N  72.6W   75 KT  85 MPH
 48H  05/0600Z 40.9N  67.9W   70 KT  80 MPH
 72H  06/0600Z 47.5N  60.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  07/0600Z 54.0N  52.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  08/0600Z 60.0N  50.0W   35 KT  40 MPH...POST-TROP/EXTRATROP

$$
Forecaster Brennan

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