[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 140857
TCDAT1

TROPICAL STORM EDOUARD DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062014
500 AM AST SUN SEP 14 2014

Edouard continues to gradually intensify, as a tightly curved band
has wrapped around the cyclone's center.  Dvorak classifications
from both TAFB and SAB are a 4.0, or 65 kt, while the CIMSS Advanced
Dvorak Technique is substantially lower.  The current intensity of
Edouard is assessed as a high-end tropical storm at 60 kt, but the
system may already be a hurricane given the uncertainties.  The
vertical shear - primarily induced by a large tropical upper
tropospheric trough to its west-southwest - has begun to relax, now
that Edouard has moved poleward of the trough axis. Vertical shear
predicted by the global models should further weaken to less than 10
kt from 24 through 72 hours.  This along with quite warm 29C waters
is likely to lead to continued intensification through three days.
The new NHC forecast peaks Edouard's intensity at 95 kt (slightly
higher than that in the previous advisory), based upon a blend of
the SHIPS statistical model and HWRF dynamical model. While the
vertical shear picks up significantly between days 3 and 4 as
Edouard recurves into the mid-latitude westerlies, the storm motion
and shear vectors are likely to align which would allow Edouard to
maintain its intensity through day 4.  By day 5, cold waters and
very strong vertical shear are anticipated to cause substantial
weakening.  Both the FSU Cyclone Phase Space analysis and the SHIPS
storm type indicate Edouard will transition to an extratropical
cyclone by day 5.

The improved organization of the deep convection as seen in the
infrared imagery as well as a couple of microwave passes allow for a
fairly confident assessment of the current position.  Edouard is
moving toward the northwest at about 12 kt, primarily due to the
steering induced by a mid-level ridge to its northwest.  Edouard
will round the western periphery of the ridge and recurve toward
the northeast about 3 days.  The NHC track prediction is based upon
the tightly clustered multi-model TVCA track ensemble and is
slightly west of that shown in the previous advisory through 72
hours and slightly east thereafter.

The tropical-storm-force wind radii of Edouard was based upon an
earlier ASCAT pass, which indicated a substantially larger size than
that previously analyzed.

FORECAST POSITIONS AND MAX WINDS

INIT  14/0900Z 24.0N  49.7W   60 KT  70 MPH
 12H  14/1800Z 25.0N  51.6W   65 KT  75 MPH
 24H  15/0600Z 26.2N  54.0W   75 KT  85 MPH
 36H  15/1800Z 27.5N  55.8W   85 KT 100 MPH
 48H  16/0600Z 28.9N  57.1W   90 KT 105 MPH
 72H  17/0600Z 33.0N  56.6W   95 KT 110 MPH
 96H  18/0600Z 38.5N  50.0W   85 KT 100 MPH
120H  19/0600Z 42.0N  39.0W   60 KT  70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Landsea


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