Hurricane EDOUARD

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HURRICANE EDOUARD DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062014
1100 AM AST SUN SEP 14 2014

Edouard's inner core convective pattern has continued to improve
since the previous advisory, with a ring of deep convection
surrounding a brief appearance of a 20 nmi diameter eye around 1200
UTC. Since that time, the eye has become cloud-covered with cirrus
from a strong convective burst in the western eyewall. A 0924 UTC
Windsat microwave overpass revealed good low-level structure and a
15-20 nmi diameter eye. Satellite intensity estimates are a
consensus T4.5/77 kt from TAFB and SAB, and UW-CIMSS ADT values
have been T4.4/75 kt for the past few hours. However, due to the
eye recently becoming cloud-filled, the initial intensity is only
being increased to 70 kt, which still makes Edouard the fourth
hurricane of the 2014 Atlantic season.

Edouard has made slight wobble to the right, possibly due to the
formation of the eye, but a 12-hour-average yields a motion of about
305/14 kt. A deep-layer subtropical ridge along 30N-32N latitude is
expected to steer the hurricane northwestward today, followed by a
turn to the north on Monday and Tuesday. On Wednesday, the cyclone
is expected to accelerate to the northeast ahead of a strong
mid-tropospheric trough that is forecast to move off of the U.S.
east coast. By Days 4 and 5, Edouard is expected to get caught up
into the strong mid-latitude westerlies and turn toward the
east-northeast. The NHC model guidance is in excellent on this
developing steering pattern, and the official forecast closely
follows the previous forecast track and the consensus model TVCA.

Given the well-developed structure noted in the Windsat imagery, a
very favorable poleward outflow pattern forecast to develop by all
of the models, and anomalously warm SSTs of 29.5C ahead of the
cyclone, there appears to be no physical reason why Edouard should
not continue to strengthen and eventually become a major hurricane
over the next 2 days or so. The only inhibiting factor could be the
dry mid-level air surrounding the cyclone, and that is the only
reason why rapid intensification is not being forecast at this
time. By Day 4 and beyond, Edouard will be moving over sub-24C SSTs
and encountering vertical wind shear greater than 25 kt, which is
expected to induce significant weakening. By Day 5, Edouard is
forecast to transition to an extratropical cyclone as the system
becomes embedded within the strong mid-latitude westerlies. The
official intensity forecast follows the trend of the previous
forecast and the SHIPS model, except that the timing of the peak
intensity has been moved forward by 24 hours, in order to coincide
with the time that Edouard will be over the warmest water and in the
lowest shear conditions.

A NOAA hurricane hunter aircraft is currently conducting a research
mission into Edouard.

FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 24.7N  50.7W   70 KT  80 MPH
 12H  15/0000Z 25.8N  52.5W   80 KT  90 MPH
 24H  15/1200Z 27.1N  54.6W   90 KT 105 MPH
 36H  16/0000Z 28.5N  56.1W  100 KT 115 MPH
 48H  16/1200Z 30.1N  56.7W  105 KT 120 MPH
 72H  17/1200Z 34.5N  54.6W   95 KT 110 MPH
 96H  18/1200Z 39.4N  47.1W   75 KT  85 MPH
120H  19/1200Z 41.7N  38.0W   60 KT  70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Stewart

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