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Tropical Storm Dolores Discussion Number   2
NWS National Hurricane Center Miami FL       EP042021
1000 AM CDT Fri Jun 18 2021
 
Recent SSMIS microwave imagery indicates that convective banding
continues to become established to the north and west of the
cyclone's center, while the overall area of deep convection is
gradually expanding.  Dvorak satellite classifications have
increased to T2.0/30 kt from TAFB and T2.3/35 kt from SAB, and the
depression is therefore being upgraded to a tropical storm with
maximum winds of 35 kt.
 
Dolores is moving toward the west-northwest (285/9 kt), to the south
of a weak mid-level ridge which extends from the northwestern
Caribbean Sea to central Mexico.  Since Dolores is now reaching the
western extent of this ridge, the storm is expected to turn
northwestward and then north-northwestward around the ridge later
today and into Saturday, reaching the coast of Colima or Jalisco by
Saturday evening.  The track models agree on this general scenario,
although there is some spread on exactly where and if the center
makes landfall.  The GFS and HWRF models show a sharper turn toward
the north, with the center moving inland near or south of the
Manzanillo area, while the ECMWF and UKMET models depict a wider
sweeping turn, keeping the center near or just off the coast in the
vicinity of Cabo Corrientes.  The updated NHC track forecast is
between these two scenarios, near the TVCE and HCCA consensus aids,
depicting a potential landfall along the Colima or Jalisco coasts
Saturday evening.  The new NHC track forecast is not too different
than the previous forecast, although it does show Dolores reaching
the coast a little sooner than previously expected.
 
Additional strengthening is anticipated up until Dolores's
potential landfall due to very warm sea surface temperatures (29 to
30 degrees Celsius), a moist environment, and significant
upper-level divergence.  The intensity models agree on this
strengthening, although since several of the track models already
have Dolores inland by 36 hours (which the NHC official forecast
does not), they're showing the cyclone's intensity too low at that
time.  The NHC intensity forecast is close to the HCCA consensus
aid through 24 hours, but then it is above all of the guidance at
36 hours in order to show at least some additional strengthening
before Dolores reaches the coast.  Based on this forecast, Dolores
is expected to be near or just below hurricane strength when it
reaches the coast.  This new forecast necessitates the 
issuance of a tropical storm warning and a hurricane watch 
for a portion of the west-central coast of Mexico.  Depending on 
the amount of land interaction after 36 hours, Dolores is expected 
to weaken fast as it continues moving northward along the 
west-central coast of Mexico.
 
Key Messages:
 
1. Dolores is expected to continue strengthening today and on
Saturday, and it could be near hurricane strength when it reaches
the coast of west-central Mexico by Saturday evening.  A tropical
storm warning and a hurricane watch are now 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  18/1500Z 14.7N 102.5W   35 KT  40 MPH
 12H  19/0000Z 15.3N 103.3W   45 KT  50 MPH
 24H  19/1200Z 16.8N 104.3W   55 KT  65 MPH
 36H  20/0000Z 19.2N 105.0W   60 KT  70 MPH
 48H  20/1200Z 22.1N 105.6W   35 KT  40 MPH...INLAND
 60H  21/0000Z 24.4N 106.2W   25 KT  30 MPH...POST-TROP/INLAND
 72H  21/1200Z...DISSIPATED
 
$$
Forecaster Berg
 
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