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Tropical Storm Dolores Discussion Number 3
NWS National Hurricane Center Miami FL EP042021
400 PM CDT Fri Jun 18 2021
Dolores is a large, sprawling tropical storm. Recent scatterometer
data indicated that the circulation remains broad, with the center
embedded within an elongated area of lighter winds. However, the
scatterometer passes also showed an extensive area of
tropical-storm-force winds extending up to 140 n mi to the
northeast of the center, blowing from east to west away from the
coast of Mexico. Based on these data, Dolores's initial winds are
set at 40 kt.
The ASCAT data indicated that Dolores's center is located a little
farther to the right, or northeast, of the previous NHC track
forecast. With this adjusted position, the initial motion is now
estimated to be northwestward (310 degrees) at 6 kt. Dolores is
moving around the western periphery of a mid-level ridge which
extends across the northwestern Caribbean Sea and southeastern
Mexico, and this feature should steer the storm northwestward to
north-northwestward during the next couple of days. All of the
reliable track models show this general trajectory, and they bring
the center inland along the coast of Michoacan, Colima, or Jalisco
during within the next 18-36 hours, with the timing depending on
the storm's exact heading. Because of the eastward adjustment of
the initial position, the new NHC track forecast has been shifted
eastward, but it still generally follows the TVCE and HCCA
consensus aids.
Environmental conditions are generally conducive for additional
strengthening, particularly warm sea surface temperatures,
mid-level relative humidity between 70 and 80 percent, and
significant upper-level divergence. The two limiting factors to
intensification are (1) the broad structure of the circulation and
(2) less potential time over water due to the eastward shift in the
track. The updated NHC intensity forecast continues to show
intensification up until landfall and is generally close to the
IVCN and HCCA consensus aids. There is still some possibility that
Dolores could be near hurricane strength when it reaches the coast
if the intensification rate is faster than indicated in the
forecast, or if the center ends up staying over water longer than
indicated. After the center crosses the coast, the mountainous
terrain of west-central Mexico should cause rapid weakening, with
the cyclone degenerating into a remnant low, and then completely
dissipating, in 2 to 3 days.
Key Messages:
1. Dolores is expected to continue strengthening tonight and on
Saturday, and it could be near hurricane strength when it reaches
the coast of west-central Mexico by Saturday afternoon. A tropical
storm warning and a hurricane watch are in effect for portions
of the southwestern and west-central coasts of Mexico.
2. Heavy rains are forecast over coastal sections of the Mexican
states of Oaxaca, Guerrero, Michoacan, Colima, Jalisco, and Nayarit
during the next few days, which could result in life-threatening
flash flooding and mudslides.
FORECAST POSITIONS AND MAX WINDS
INIT 18/2100Z 15.6N 102.3W 40 KT 45 MPH
12H 19/0600Z 16.6N 103.1W 50 KT 60 MPH
24H 19/1800Z 18.5N 104.0W 55 KT 65 MPH
36H 20/0600Z 21.2N 104.7W 35 KT 40 MPH...INLAND
48H 20/1800Z 23.6N 105.4W 25 KT 30 MPH...POST-TROP/INLAND
60H 21/0600Z...DISSIPATED
$$
Forecaster Berg
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