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Tropical Depression Nineteen-E Discussion Number 1
NWS National Hurricane Center Miami FL EP192020
400 PM CDT Mon Oct 05 2020
Satellite imagery and ASCAT-C data indicate that the area of low
pressure located several hundred miles south of the southwestern
coast of Mexico has become better-defined today. The associated
deep convection has also become more organized and convection has
persisted over the low-level center since early this morning. In
addition, a banding feature has also developed over the western
portion of the circulation. Based on these trends, advisories have
been initiated for Tropical Depression Nineteen-E. The ASCAT data
showed winds as high as 32 kt. However, these vectors were at the
very edge of the data swath, and may be unreliable. The initial
intensity of 30 kt is therefore based off the latest Dvorak
intensity estimate from TAFB.
The forecast for the depression is not straightforward and there is
a larger than normal amount of uncertainty for both the future track
and intensity of the cyclone. The global models generally do not
favor much strengthening beyond 24 h and some of the guidance,
including the GFS and HWRF indicate weakening. On the other hand,
the SHIPS guidance suggests gradual strengthening and indicate the
cyclone could be near hurricane intensity by the end of the 5-day
forecast period. The overall environment appears conducive for
the depression to intensify over the next several days, with very
warm SSTs, low vertical wind shear, and plenty of atmospheric
moisture to work with. One negative influence that the global models
could be picking up on is an ongoing interaction with the larger
scale Intertropical Convergence Zone (ITCZ). The NHC forecast, out
of respect for the skilled global and dynamical models, does not
show as a robust rate of strengthening as suggested by the SHIPS
guidance. However, some intensification is indicated throughout the
forecast period due to the aforementioned favorable environmental
factors.
The initial motion of the depression is 340/6 kt. This motion is
expected to continue through tonight as the depression is steered
by a mid-level ridge centered over southern Mexico. The ridge is
forecast to weaken tomorrow and steering currents over the
depression are expected to collapse through the middle of the week.
The track guidance is highly divergent after 48 h, as the models
appear to steer the cyclone in varying directions based off the
interaction with the ITCZ in the midst of weak synoptic steering.
By the end of the forecast period, the models are generally in
better agreement on a slow northwesterly motion as the ridge
rebuilds to the northeast of the cyclone. The NHC track forecast
lies near the HFIP corrected consensus HCCA.
FORECAST POSITIONS AND MAX WINDS
INIT 05/2100Z 12.8N 105.4W 30 KT 35 MPH
12H 06/0600Z 13.5N 105.9W 35 KT 40 MPH
24H 06/1800Z 13.9N 106.5W 35 KT 40 MPH
36H 07/0600Z 13.7N 106.8W 35 KT 40 MPH
48H 07/1800Z 13.5N 106.8W 40 KT 45 MPH
60H 08/0600Z 13.5N 106.6W 40 KT 45 MPH
72H 08/1800Z 13.6N 106.5W 40 KT 45 MPH
96H 09/1800Z 13.7N 106.9W 45 KT 50 MPH
120H 10/1800Z 14.7N 108.2W 45 KT 50 MPH
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Forecaster Latto
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