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Tropical Depression SIX-E


Tropical Depression Six-E Discussion Number   2
NWS National Hurricane Center Miami FL       EP062017
300 AM MDT Wed Jul 12 2017

The structure of the depression has changed little during the past
few hours, with the low-level center still located on the eastern
edge of a central cluster of deep convection.  Dvorak intensity
estimates from TAFB and SAB are T2.5/35 kt and T1.5/25 kt, while
the objective ADT estimate is T2.0/30 kt.  The initial intensity
therefore remains 30 kt.

Low- to mid-level high pressure is currently located north of the
depression near the Baja California peninsula, and it is steering
the cyclone westward at 270/10 kt.  This ridging is expected to
strengthen and build westward through the forecast period,
imparting a continued westward or even south-of-due-west motion on
the cyclone through day 5.  In fact, with the exception of the
UKMET, the other track models have shifted notably southward from
the previous NHC forecast for the first 72 hours.  The updated NHC
track forecast has also been shifted southward, close to the TVCN
multi-model consensus, but it is not as far south as the ECMWF,
HWRF, and HCCA models.  Therefore, it wouldn't be surprising to see
additional southward adjustments in future forecast packages.

Various shear analyses place 10-15 kt of northeasterly shear over
the depression, and that shear is likely to continue for another
24-36 hours.  In the meantime, the depression is moving over very
warm waters of 28-29 deg C, and the cyclone's forecast low latitude
should keep it over warm water for the duration of the forecast
period.  The global models, particularly the GFS and ECMWF, seem to
suggest that significant deepening won't occur for another 24-48
hours (possibly due to the ongoing shear).  Gradual strengthening
is therefore forecast initially, and the NHC forecast is close to a
blend of the SHIPS and HCCA models for the first 48 hours.  After
48 hours, many of the models show more significant intensification
due to lower shear, and during that period the NHC forecast is
close to HCCA and the ICON intensity consensus.  This new forecast
is a little higher than the previous one on days 3, 4, and 5.


INIT  12/0900Z 12.1N 110.7W   30 KT  35 MPH
 12H  12/1800Z 12.1N 112.0W   35 KT  40 MPH
 24H  13/0600Z 12.1N 113.9W   45 KT  50 MPH
 36H  13/1800Z 12.0N 115.8W   55 KT  65 MPH
 48H  14/0600Z 11.9N 117.8W   65 KT  75 MPH
 72H  15/0600Z 11.8N 122.4W   80 KT  90 MPH
 96H  16/0600Z 12.2N 127.3W   90 KT 105 MPH
120H  17/0600Z 12.7N 132.0W   90 KT 105 MPH

Forecaster Berg