ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM

Tropical Depression Narda Discussion Number   6
NWS National Hurricane Center Miami FL       EP162019
400 PM CDT Sun Sep 29 2019

Narda has become less organized during the past several hours.  The
primary center has been over the mountains of southwestern Mexico
between Lazaro Cardenas and Manzanillo, and the associated
convection has been decreasing.  A 17Z ASCAT-C overpass suggests
two other vorticity centers are located offshore, one near a
cluster of convection to the southwest of Manzanillo and the other
to the southwest of Lazaro Cardenas.  The scatterometer data showed
35 kt winds southeast of the primary center, and given the decrease
in organization since that time it is estimated that Narda has
dropped below tropical storm strength.

The initial motion is a rather uncertain 315/17 kt, which is
faster than in the previous advisory.  Over the next couple of days,
Narda will be steered generally northwestward close to the coast
of mainland Mexico along the southwestern periphery of a large high
pressure area.  After that time, a mid- to upper-level trough
approaching the northern Baja California peninsula from the west
should cause the system to turn north-northwestward and move over
northwestern mainland Mexico.  The track guidance has shifted to the
right since the last advisory.  However, due to the uncertainty in
what will happen to the center, including the possibility it could
re-form offshore, the new forecast track will be to the left of the
model consensus.  The new track will be faster than the previous
track based on a combination of the initial motion and faster
guidance.

The intensity forecast is highly uncertain.  The official forecast
will follow the previous forecast in calling for Narda to weaken
while over Mexico, and then re-intensify a little when the
system emerges over water.  However, there remain two alternative
scenarios.  The first of these is that the circulation dissipates
completely as it passes over the mountains of western Mexico.  The
second is that the center re-forms offshore, either from the
vorticity center currently southwest of Manzanillo or, as suggested
by some of the global models, from a new center north of Cabo
Corrientes.  If such a re-formation occurs, this could lead to
significant changes in both the intensity and the track forecasts.

The primary threat from Narda is very heavy rainfall, which should
result in life-threatening flash flooding and mudslides over
portions of the southern coast of Mexico.  Rainfall totals of up to
15 inches are possible.  This rainfall threat is expected to
continue even if the system dissipates as a tropical cyclone.


FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 19.1N 103.5W   30 KT  35 MPH...INLAND
 12H  30/0600Z 20.8N 105.2W   25 KT  30 MPH...INLAND
 24H  30/1800Z 23.0N 106.9W   25 KT  30 MPH...OVER WATER
 36H  01/0600Z 24.7N 108.4W   30 KT  35 MPH
 48H  01/1800Z 25.7N 109.5W   35 KT  40 MPH
 72H  02/1800Z 28.5N 110.5W   30 KT  35 MPH...INLAND
 96H  03/1800Z...DISSIPATED

$$
Forecaster Beven

NNNN