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Tropical Depression EIGHT-E


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TROPICAL DEPRESSION EIGHT-E DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP082015
800 PM PDT MON JUL 27 2015

The depression has become somewhat less organized since the last
advisory.  The center has become exposed to the northwest of an
amorphous but persistent mass of deep convection.  According to the
UW-CIMSS shear analyses, the cyclone's appearance is a result of
northwesterly shear of around 20 kt associated with an upper-level
trough located to its northeast.  Last-light visible satellite
images also showed arc clouds on the fringes of the eastern half of
the circulation, indicative of dry air entrainment.  A satellite
classification of T2.0 from both SAB at 0000 UTC is used to maintain
the initial intensity at 30 kt.

Any opportunity for the depression to strengthen is expected to be
in the very short term.  Water vapor imagery shows the cyclone
moving into a region dominated by very dry mid- to
upper-tropospheric air.  The dry air, in combination with lower sea
surface temperatures and greater atmospheric stability, should
result in weakening after 24 to 36 hours.  Global models show
the system opening up into a trough in about 3 days in an
increasingly unfavorable environment, around the time it crosses
140W.  Like the previous forecast, this one shows little
intensification, followed by weakening.  However, dissipation is
predicted much sooner (by 96 hours) based on the latest guidance.

The initial motion estimate is 290/12.  A low- to mid-level ridge
over the subtropical eastern Pacific should steer the cyclone on a
west-northwestward course during the next few days.  The model
solutions diverge to some degree after 12 to 24 hours, due to
their handling of the strength of this feature.  The GFS and its
ensemble mean have a weaker ridge and are farthest north while the
ECWMF, with a stronger ridge, is on the southern side of the
guidance envelope.  The new forecast track results in little
overall change from the previous one and is nearly split between
the ECMWF and GFS, near the multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 16.0N 127.0W   30 KT  35 MPH
 12H  28/1200Z 16.4N 128.7W   30 KT  35 MPH
 24H  29/0000Z 16.9N 131.0W   35 KT  40 MPH
 36H  29/1200Z 17.2N 133.3W   35 KT  40 MPH
 48H  30/0000Z 17.5N 135.8W   30 KT  35 MPH
 72H  31/0000Z 18.0N 141.3W   25 KT  30 MPH
 96H  01/0000Z...DISSIPATED

$$
Forecaster Kimberlain

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