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Tropical Depression Narda Discussion Number   7
NWS National Hurricane Center Miami FL       EP162019
1000 PM CDT Sun Sep 29 2019

My best estimate of Narda's position based on conventional and
microwave satellite imagery, along with surface observations, is
inland near Puerto Vallarta, Mexico. There may be other small swirls
embedded within a surface trough that lies from the Islas Marias
archipelago southeastward to Puerto Vallarta, Narda, and Manzanillo.
However, the mid-level circulation center that we have been
tracking, which is near ground level in this mountainous region, is
the feature that has had the most continuity. A curved band of
intense deep convection consisting of cloud tops of -85C to -90C,
with isolated overshooting tops to -95C, wraps about half around the
center and generally corresponds to 35-kt winds. Due to land
interaction, however, the initial intensity is being held just below
tropical storm strength or 30 kt.

The initial motion is 315/18 kt. A large ridge anchored to the east
of Narda is expected to steer the the cyclone northwestward for the
next 3 days. This will result in Narda emerging back over the
Pacific Ocean in about 6 hours, then passing near or over the Islas
Marias islands Monday morning, followed by a track near or just
offshore the northwestern coast of Mexico Monday night and Tuesday.
A second landfall is expected along the coast of Mexico on
Wednesday, followed by dissipation Wednesday night or early
Thursday. The new NHC forecast track is similar to the previous
advisory, and lies just a tad to the left of the consensus models
TVCN and HCCA, which move the center inland in about 24 hours.

The intensity forecast remains highly uncertain, and leans toward a
consensus of the wind fields in the global models, which show Narda
regaining tropical storm status in 6-12 hours as a band of 35-kt
winds forms between the center and the mountainous coastline, likely
due to funneling/orographic effects. The upper-level environment is
forecast to be conducive for additional strengthening when Narda
moves over the very warm waters of the Gulf of California after
12-18 hours, but land interaction is expected to temper any
significant strengthening. Thus, the intensity forecast is
flat-lined at 35-kt, although some fluctuations in the intensity is
likely. Due to Narda being forecast to regain tropical storm status,
tropical storm warnings and watches have been issued for portions of
northwestern Mexico.

The primary threat from Narda will continue to be 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  30/0300Z 20.6N 105.2W   30 KT  35 MPH...INLAND
 12H  30/1200Z 22.0N 106.4W   35 KT  40 MPH...OVER WATER
 24H  01/0000Z 24.0N 108.0W   35 KT  40 MPH
 36H  01/1200Z 25.4N 109.4W   35 KT  40 MPH
 48H  02/0000Z 26.7N 110.3W   35 KT  40 MPH
 72H  03/0000Z 29.2N 111.4W   30 KT  35 MPH...INLAND
 96H  04/0000Z...DISSIPATED INLAND

$$
Forecaster Stewart

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