[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

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


This weather bulletin was brought to you by:
www.nashvilleweather.net