AXPZ20 KNHC 212218
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Sun Oct 21 2018
Tropical Weather Discussion for the eastern Pacific Ocean from
the Equator to 32N, east of 140W. The following information is
based on satellite imagery, weather observations, radar, and
Based on 1800 UTC surface analysis and satellite imagery through
Hurricane Willa centered near 17.0N 107.0W at 2100 UTC moving
NNW at 5 kt. Estimated minimum central pressure is 963 mb.
Maximum sustained wind speed has increased to 100 kt with gusts
to 120 kt. A well defined 8 nm wide eye has cleared out in the
past few hours, and suggests a rapid intensification process is
now underway. Numerous strong convection is observed within 60
nm N and 75 nm S of the eye, surrounded by scattered moderate to
strong convection in bands within 300 nm of the center. Some of
these rain bands will bring very heavy rainfall to the Pacific
coast of Mexico from Michoacan to Sinaloa in the next few days.
Willa will continue to make a gradual N turn during the next 24
hours and then veer more NE late Mon and Mon night, then cross
Las Tres Marias Tue afternoon before accelerating to the NE and
entering the coast of Sinaloa Tue night. Swells generated by
Willa will begin to reach portions of the coast of southwestern
and west-central Mexico this afternoon and tonight, and will
produce very large and power surf and life-threatening rip
current conditions. Please refer to local forecasts from the
Meteorological Service of Mexico for specific information on
heavy rainfall and flash flood potential from Willa. Refer to
the latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMEP4/WTPZ24 KNHC for additional details.
Tropical Storm Vicente centered near 14.2N 97.9W at 2100 UTC
moving W at 9 kt. Estimated minimum central pressure is 1005 mb.
Maximum sustained wind speed is 35 kt with gusts to 45 kt. The
low level center of Vicente became partially exposed earlier
this afternoon and was located on the NE edge of the associated
convection. However, in the past few hours convection has
developed over the center again. Scattered moderate to strong
convection is observed in bands within 30 nm NE and 120 nm SW
semicircle of the center. Vicente will continue on a general
westward track across the southern Mexican offshore waters
through Mon and then begin to veer NW and follow Willa in a
parallel track, and move inland between Michoacan and Jalisco
Tue night. The main threat of Vicente will be very heavy
rainfall as it moves into the Mexican coastline across areas
that will also received very heavy rainfall from Willa. Refer to
the latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMEP3/WTPZ23 KNHC for additional details.
A tropical wave is analyzed N of 08N along 85W. Scattered
moderate to strong convection continues to flare along and east
of the wave, from 04N TO 08N E of 91W.
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
The monsoon trough extends W off the Caribbean coast of Colombia
at 10N76W to 12N92W where it loses identity to the east of
Tropical Storm Vicente. The monsoon trough then resumes SW of
Hurricane Willa at 13N110W, and continues SW through an embedded
surface low at 11N117.5W to 09N127W, then turns W-NW to beyond
Scattered moderate to strong convection is observed within 90 nm
N and 120 nm S of the trough westward of 128W.
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...
See the Special Features paragraph for details on Tropical
Cyclones Vicente and Willa.
A ridge extends from a 1021 mb surface high near 35N135W
southeastward through 30N131W to 17N114W and will retract
slightly to the W tonight as the high shifts SW and reorganizes.
Gentle to locally moderate NW to N flow is expected N of 20N W
of 110W through Mon night when the pressure gradient is forecast
to tighten, supporting moderate northerly flow W of the Baja
California Peninsula by the middle of the week. Additionally,
large southerly swell from Hurricane Willa will propagate
northward and into the waters between Cabo Corrientes and Baja
California Sur tonight through Mon, and spread farther northward
across the remaining Baja waters late Mon through Tue before
beginning to subside Wed.
Gulf of California: Light, mostly northerly flow is expected
through late Mon across the Gulf. Large southerly swell from
Hurricane Willa will begin to propagate into the southern gulf
waters tonight and dominate seas through Wed. Fresh to locally
strong northerly winds are expected across the gulf waters S of
24.5N on Tue night into Wed as Willa passes S of the gulf
entrance. Bands of showers and thunderstorms associated with
Willa will impact the coastal states from Jalisco to Sinaloa Mon
and Tue ahead of the expected landfall of Willa.
Gulf of Tehuantepec...Fresh northerly winds, with 6 to 8 ft seas
are forecast N of 15N today as Tropical Storm Vicente passes to
the S. Fresh to locally strong northerly flow is expected to
continue through Mon, with nocturnal drainage flow Mon night
diminishing during the day on Tue.
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND
WITHIN 750 NM OF ECUADOR...
Gulf of Papagayo...Pulses of fresh NE flow are forecast through
Light northerly winds and 4 to 7 ft seas are forecast elsewhere
N of the monsoon trough, while moderate to locally fresh
southwesterly monsoonal wind flow, and seas of 5 to 8 ft in
SW swell are expected through late Mon.
REMAINDER OF THE AREA...
Refer to the Special Features paragraph above for details on
Tropical Cyclone Willa.
A weak 1010 mb low will meander near 11N118W for the next few
days with moderate southerly flow and 6 to 8 ft seas forecast
within 280 nm SE of the low. The surface high mentioned above
will drift SW to near 29N136W through Tue, with moderate to
locally fresh anticyclonic flow forecast across the tropical
waters N of the monsoon trough and ITCZ, and W of 122W through
the middle of the week. An area of 7 to 9 ft seas is observed
across the tropical waters W of a line from 09N140W TO 12N131W
TO 26N140W, in mixed ENE wind waves and other mixed swell. These
conditions will gradually shrink in areal coverage and shift
slowly W through Tue.