Tropical Storm EDOUARD

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TROPICAL STORM EDOUARD DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062014
1100 PM AST FRI SEP 12 2014

Edouard's cloud pattern has changed little in organization since
the last advisory.  Moderately strong south-southwesterly shear is
still affecting the cyclone, as evidenced by the center location
near the southern edge of the main convective mass in microwave
imagery.  However, convective cloud top temperatures have cooled
some, and the upper-level outflow has expanded to the north and
west. Dvorak intensity estimates range from T2.5/35 kt from TAFB and
SAB, while an earlier AMSU estimate suggested an intensity of around
45 kt. A blend of these data yields an initial intensity of 40 kt.

The center of Edouard was relocated a bit to the south and west
based on a 2113 UTC Windsat overpass.  That pass, in combination
with previous fixes, suggests an initial motion estimate of 295/11.
Edouard should move generally west-northwestward for the next few
days under the influence of a mid-level ridge over the central
Atlantic. In about 3 days, the cyclone should reach a significant
break in the the same ridge and gradually turn northward between
55-58w with some decrease in forward speed.  The cyclone should
accelerate northeastward once it becomes embedded in deep-layer
westerly flow over the north Atlantic toward the end of the forecast
period. The NHC track forecast is shifted to the left of the
previous one through 72 hours due to the the center relocation and a
westward trend in the track guidance this cycle.  The track forecast
lies on the right side of the guidance envelope through 3 days and
is near the center of it after that, close to the multi-model
consensus.

Edouard has been moving through a sheared environment over the
tropical Atlantic, characterized by strong low- to mid-level
easterly trades and southerly flow aloft. Global models generally
forecast a reduction of this shear after another day or so, when
upper-level anticyclonic flow develops over the storm.  In a couple
of days, upper-level troughs to the east and west of Edouard could
allow the formation of dual outflow channels while the cyclone is
over sea surface temperatures around 30 deg C.  This should allow
intensification to hurricane strength.  After recurvature, the storm
motion and shear vectors are likely to align which should allow
Edouard to maintain its intensity until it encounters increasing
shear and cooler waters by day 5. The NHC wind speed forecast is
nearly unchanged relative to the previous, except to show a slightly
higher peak intensity in agreement with the latest guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 19.5N  45.2W   40 KT  45 MPH
 12H  13/1200Z 20.4N  46.7W   45 KT  50 MPH
 24H  14/0000Z 21.8N  48.7W   50 KT  60 MPH
 36H  14/1200Z 23.1N  50.8W   60 KT  70 MPH
 48H  15/0000Z 24.6N  53.1W   65 KT  75 MPH
 72H  16/0000Z 27.9N  56.4W   80 KT  90 MPH
 96H  17/0000Z 32.2N  56.6W   80 KT  90 MPH
120H  18/0000Z 37.0N  52.0W   75 KT  85 MPH

$$
Forecaster Kimberlain

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