[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 092035
TCDAT1

TROPICAL STORM ANA DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012015
500 PM EDT SAT MAY 09 2015

Ana continues to maintain deep convection near and east of the
center, although the convection is rather ragged-looking.  There is
weak upper-level outflow over the southern portion of the
circulation.  The current intensity is held at 50 kt, in agreement
with data from an ASCAT overpass from several hours ago.  Since the
storm will be moving over progressively cooler waters as it departs
the Gulf Stream, and is being influenced by northwesterly shear and
some dry air, gradual weakening is forecast until landfall.  After
Ana crosses the coast, the weakening will of course be more rapid.
The official intensity forecast is again close to IVCN, the
intensity model consensus.  Global model guidance indicates that
Ana or its post-tropical remnant will become absorbed by, or merge
with, a large extratropical cyclone over Atlantic Canada within 72
hours.

The center is a little difficult to locate, but my best estimate of
the initial motion is 320/3.  The track forecast philosophy
continues unchanged.  The persistent mid-tropospheric blocking
ridge to the north of Ana is predicted by the global models to
shift eastward and weaken during the next day or so.  The models
also depict a broad trough moving eastward from the central to the
eastern U.S. over the next 2-3 days.  This evolution of the
steering currents should cause Ana to turn northward and
northeastward.  The official track forecast is similar to the
dynamical model consensus, IVCN, but leans a little more toward the
latest ECMWF solution.

FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 32.9N  78.3W   50 KT  60 MPH
 12H  10/0600Z 33.4N  78.6W   45 KT  50 MPH
 24H  10/1800Z 34.2N  78.7W   35 KT  40 MPH...INLAND
 36H  11/0600Z 35.2N  78.1W   30 KT  35 MPH...INLAND
 48H  11/1800Z 36.7N  76.5W   30 KT  35 MPH...INLAND
 72H  12/1800Z...ABSORBED

$$
Forecaster Pasch
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