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Tropical Storm Eugene Discussion Number   1
NWS National Hurricane Center Miami FL       EP052017
300 PM MDT Fri Jul 07 2017

The area of low pressure several hundred miles south of the southern
tip of the Baja California peninsula has become better organized
during the past several hours.  Earlier microwave images and current
enhanced BD-curve infrared imagery show well-developed deep
convective spiral bands over the northeast and southwest quadrants.
A recent ASCAT-B overpass indicated that surface circulation has
become more symmetric and tropical-storm-force winds are located in
the convective band to the northeast of the center. Consequently,
the system is being classified as a tropical storm at this time. The
initial intensity is set at 35 kt based primarily on the
scatterometer data.  Eugene is expected to remain in an environment
of low shear, warm sea surface temperatures, and a moist low- to
mid-level troposphere through 48 hours.  Afterward, the cyclone is
forecast to traverse decreasing SSTs, which should induce a slow
weakening through the remainder of the period. The intensity
forecast is weighed heavily on the IVCN multi-model consensus and
shows the cyclone reaching hurricane strength before moving over
cooler waters.

The initial motion is estimated to be northwestward, or 310/7 kt. A
retrograding mid-tropospheric trough currently centered over
northwestern Mexico has created a weakness in the subtropical ridge,
which will allow Eugene to continue moving northwestward through day
5.  The global and ensemble models are in good agreement with this
large-scale scenario, although the UKMET is a bit of an outlier on
the left side of the guidance suite. The NHC track forecast is near
the center of the guidance envelope, and is close to the multi-model
TVCN and the HFIP corrected consensus HCCA.

FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 11.9N 111.2W   35 KT  40 MPH
 12H  08/0600Z 12.6N 111.9W   45 KT  50 MPH
 24H  08/1800Z 13.8N 113.0W   55 KT  65 MPH
 36H  09/0600Z 15.1N 114.3W   60 KT  70 MPH
 48H  09/1800Z 16.6N 115.5W   70 KT  80 MPH
 72H  10/1800Z 19.5N 117.9W   65 KT  75 MPH
 96H  11/1800Z 22.0N 120.0W   50 KT  60 MPH
120H  12/1800Z 24.4N 121.8W   40 KT  45 MPH

$$
Forecaster Roberts

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