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Tropical Storm Narda Discussion Number 12
NWS National Hurricane Center Miami FL EP162019
300 AM MDT Tue Oct 01 2019
The ill-defined surface center of Narda is a bit difficult to find
this morning, but the best estimate, using conventional satellite
imagery, is just offshore of the mainland Mexico coast and about 30
miles southeast of the now decoupled mid-level circulation. The
majority of the deep convection associated with the cyclone has
moved inland. However, sustained tropical-storm-force winds may
still exist along and just offshore of the coast, north of Los
Mochis, Sinaloa and south of Guaymas, Sonora. Based on the
deteriorating satellite presentation, and a blend of the satellite
intensity estimates from TAFB and SAB, the initial intensity is
lowered to 35 kt.
Although Narda's center has re-emerged over the Gulf of California,
further weakening is still forecast, and dissipation of the cyclone
is anticipated as it once again moves inland over the rugged terrain
of coastal Mainland Mexico on Wednesday. It's worth noting,
however, that a couple of the large-scale models indicate Narda's
remnants drifting back just offshore over the central Gulf of
California prior to dissipation.
The initial motion is estimated to be northwestward, or 325/12 kt.
This general northwestward motion, within the mid-level southwestern
peripheral flow of strong high pressure ridging to the northeast, is
expected until the cyclone dissipates, and the new NHC forecast
track is changed little from the previous one.
The main hazard produced by Narda continues to be very heavy
rainfall, due to large amounts of deep-layer moisture being
advected northward and northeastward over Mexico on the eastern side
of the cyclone's circulation. These rains, which could total as
much as 15 inches in a few locations, will result in
life-threatening flash floods and mudslides. Furthermore, the very
humid mid- and upper-level remnant moisture plume is expected to
spread northeastward across northern Mexico and into portions of the
U.S. Southern and Central Plains through Wednesday, enhancing the
threat for heavy rainfall and flash flooding in these areas. For
additional information, please see excessive rainfall products
issued by the NOAA Weather Prediction Center at
https://www.wpc.ncep.noaa.gov/qpf/excess_rain.shtml.
FORECAST POSITIONS AND MAX WINDS
INIT 01/0900Z 26.6N 109.7W 35 KT 40 MPH
12H 01/1800Z 27.9N 110.7W 30 KT 35 MPH...INLAND
24H 02/0600Z 29.2N 111.6W 25 KT 30 MPH...INLAND REMNT LOW
36H 02/1800Z...DISSIPATED
$$
Forecaster Roberts
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