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Tropical Depression Three-E Discussion Number 1
NWS National Hurricane Center Miami FL EP032021
200 PM PDT Sat Jun 12 2021
The disturbance that has been tracked westward for the past several
days across the open waters of the the tropical eastern Pacific has
finally established a sufficiently well-defined low-level
circulation to be designated as Tropical Depression Three-E.
Convection increased last night and began to consolidate, while
satellite images and microwave data this morning indicated that
there was evidence of a well-defined low developing. This was later
confirmed by a pair of ASCAT overpasses. These overpasses showed a
compact radius of maximum winds. And, although the ASCAT-A data
had a few vectors between 30-35 kt, these were not homogeneous and
appeared unrepresentative of the system's intensity. In addition,
the rather ragged satellite appearance and the Dvorak intensity
estimate of 2.0 from SAB are suggestive that this system should be
initialized as a 30-kt depression for this advisory.
The environment surrounding the depression is moderately conducive
for gradual strengthening, with SSTs of 27-28 degrees C, mid-level
RH values between 50-60 percent, and vertical wind shear of about
5-10 kt. These conditions are expected to continue for the next 2-3
days. By 72 h, dry air and subsidence are expected to hinder any
further intensification and should begin a weakening trend. By late
in the forecast period, the system is forecast to cross the 26
degree C isotherm, which should hasten the pace of weakening. The
official intensity closely follows the HFIP corrected consensus
HCCA, which shows the depression becoming a tropical storm tonight,
and levels off its intensity by 48 h, followed by a weakening trend
after 60 h.
A mid-level ridge to the north of the cyclone is steering it at a
somewhat uncertain 275/08 kt. This ridge is forecast by nearly all
of the models to weaken over the next couple of days, leaving the
depression in a region of very weak steering currents through
early next week. A mid-upper level trough digging southward to the
northwest of the cyclone should induce a northerly component of
motion along with an increase in forward speed by midweek. As
said, there is good agreement on the pattern, however, the models
vary greatly on how abruptly they slow the system. This is resulting
in a track model spread of about 300 n mi by 72 h. The NHC track
forecast tries to split the difference by closely following the TVCE
and TVCN consensus aids.
FORECAST POSITIONS AND MAX WINDS
INIT 12/2100Z 11.8N 123.6W 30 KT 35 MPH
12H 13/0600Z 11.9N 124.5W 35 KT 40 MPH
24H 13/1800Z 11.7N 125.5W 40 KT 45 MPH
36H 14/0600Z 11.4N 126.1W 45 KT 50 MPH
48H 14/1800Z 11.0N 126.5W 50 KT 60 MPH
60H 15/0600Z 10.8N 126.7W 50 KT 60 MPH
72H 15/1800Z 11.0N 126.9W 45 KT 50 MPH
96H 16/1800Z 12.5N 126.7W 40 KT 45 MPH
120H 17/1800Z 15.2N 126.1W 30 KT 35 MPH
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Forecaster Latto
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