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Hurricane ISELLE (Text)

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HURRICANE ISELLE DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092014
200 AM PDT SAT AUG 02 2014

Satellite images indicate that Iselle continues to become better
organized during the past several hours with a ragged eye feature
present on the shortwave infrared channel.  Microwave data also
show that the inner core has become better defined on the last
SSMI/S pass.  There is quite a disparity, however, of current
satellite intensity estimates, ranging from 55 to 90 kt.  Since the
cyclone appears somewhat better organized than 6 hours ago, the wind
speed is raised to 70 kt, but this estimate is more uncertain than
average.

Iselle has turned westward and appears to be moving 280/9,
although recently has wobbled due westward.  The subtropical ridge
to the northwest of the cyclone should remain firm for the next
several days, continuing the general westward motion. There has been
a notable southward shift to most of the guidance overnight with
less influence now expected from a digging trough along 130W in a
couple of days.  The ridge is expected to strengthen at long range,
causing a faster westward motion at that time.  The new NHC track
forecast is shifted southward at all times, especially at Day 3 and
beyond, close to the model consensus.

Although Iselle has good inner core structure, a combination of
moderate northeasterly shear and decreasing SSTs is expected to
limit the chance for significant strengthening over the next couple
of days.  However, the overall environment is not that unfavorable,
so little change in wind speed is forecast through 48 hours.  After
that time, the cyclone will likely encounter drier air aloft,
marginal SSTs and more significant shear by Day 5, which should
cause weakening.   The new forecast is kept very similar to the
previous forecast, which lies near the model consensus.



FORECAST POSITIONS AND MAX WINDS

INIT  02/0900Z 14.8N 128.4W   70 KT  80 MPH
 12H  02/1800Z 15.0N 129.6W   75 KT  85 MPH
 24H  03/0600Z 15.4N 131.4W   75 KT  85 MPH
 36H  03/1800Z 15.7N 133.2W   75 KT  85 MPH
 48H  04/0600Z 16.0N 134.8W   75 KT  85 MPH
 72H  05/0600Z 16.0N 138.0W   70 KT  80 MPH
 96H  06/0600Z 16.0N 141.5W   60 KT  70 MPH
120H  07/0600Z 16.5N 147.0W   45 KT  50 MPH

$$
Forecaster Blake

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