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Tropical Depression Norbert Discussion Number 13
NWS National Hurricane Center Miami FL EP192020
300 PM MDT Thu Oct 08 2020
Norbert has a ragged and disorganized appearance, with asymmetrical
convection bursting intermittently around the center. Satellite
imagery suggests that the system is now experiencing some
southeasterly shear. A recent ASCAT overpass sampled peak winds of
24 kt, so the advisory intensity will remain 25 kt.
The current environment surrounding Norbert is not forecast to
change much over the next few days. Therefore, only minor
fluctuations in intensity are expected to occur during that time. By
72 h, model guidance is indicating that the cyclone should encounter
a more stable atmosphere, which would limit convection and cause
Norbert to weaken. The cyclone is forecast to degenerate into a
remnant low devoid of deep convection by day 4, but it is possible
that the deep convection could dissipate long enough for Norbert to
be declared a remnant low before that time. Another plausible
scenario is that Norbert's low level circulation dissipates and
opens up into a surface trough later in the forecast period. The
only change to the latest NHC forecast is that no further
strengthening is indicated, which is agreement with every available
intensity model except the SHIPS guidance.
Norbert has barely budged since early this morning due to a lack of
steering currents. A weak mid-level ridge is forecast to build to
the northeast of the cyclone Friday through Saturday, which should
cause Norbert to eventually move west-northwest to northwest. By
Sunday, however, a mid-upper level low digging across northern
Mexico should weaken the ridge, and the model guidance has trended
toward Norbert once again meandering for a couple of days. By day 5,
low-level ridging building to the northwest of Norbert should cause
the shallow system to begin a westward motion. Due to the lack of
run-to-run model consistency in the 3-5 day period, that portion of
the track forecast is of low confidence. The NHC forecast track was
changed little through 48 h, then is slower at 60-96 h to reflect
the second collapse of the steering currents.
FORECAST POSITIONS AND MAX WINDS
INIT 08/2100Z 13.1N 106.1W 25 KT 30 MPH
12H 09/0600Z 13.0N 106.2W 25 KT 30 MPH
24H 09/1800Z 13.3N 106.7W 25 KT 30 MPH
36H 10/0600Z 13.9N 107.3W 25 KT 30 MPH
48H 10/1800Z 14.5N 107.6W 25 KT 30 MPH
60H 11/0600Z 14.8N 107.6W 25 KT 30 MPH
72H 11/1800Z 14.9N 107.7W 25 KT 30 MPH
96H 12/1800Z 15.0N 107.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 13/1800Z 15.1N 109.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
$$
Forecaster Latto
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