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HURRICANE DOLORES DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052015
900 AM MDT WED JUL 15 2015

Dolores has stopped strengthening for the moment, with some warming
of the convective tops noted within the northern semicircle since
the last advisory.  Although Dvorak final-T numbers from TAFB and
SAB fell to 5.5, the initial intensity is being held at 115 kt
based on the CI numbers.  Low vertical wind shear and very warm
ocean waters should support additional strengthening during the next
12-24 hours, and the official forecast keeps Dolores as a category 4
hurricane during this period.  Weakening is expected after 24 hours,
predominantly due to gradually cooler waters and a more stable
environment.  The NHC intensity forecast is near the high end of the
guidance during the first 48 hours and then close to the IVCN
consensus thereafter.  As will be discussed below, Dolores's
forecast track has been shifting southward, which would keep the
cyclone over warmer water and possibly result in slower or delayed
weakening.

Dolores's eye wobbled westward recently, but a longer-term motion
is 290/5 kt.  A mid-tropospheric ridge located over northern Mexico
should propel Dolores west-northwestward or even westward during
the next 72 hours.  After that time, there are some model
differences regarding the strength of the ridge and whether Dolores
will turn northwestward by the end of the forecast period.  At the
extremes, the GFS maintains a strong ridge and keeps Dolores to the
south, while the ECMWF weakens the ridge off the California coast
and allows Dolores to turn northward.  Despite these differences,
the overall guidance envelope has continued to shift southward, and
the updated NHC track forecast follows that trend.

FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 18.4N 110.2W  115 KT 130 MPH
 12H  16/0000Z 18.8N 111.0W  125 KT 145 MPH
 24H  16/1200Z 19.4N 112.2W  120 KT 140 MPH
 36H  17/0000Z 19.8N 113.8W  110 KT 125 MPH
 48H  17/1200Z 20.0N 115.3W   95 KT 110 MPH
 72H  18/1200Z 20.9N 118.7W   70 KT  80 MPH
 96H  19/1200Z 23.0N 122.0W   50 KT  60 MPH
120H  20/1200Z 25.5N 125.0W   35 KT  40 MPH

$$
Forecaster Berg

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