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Eastern North Pacific Tropical Weather Discussion

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 
meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through 
2100 UTC.      


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.


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.



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.  


Gulf of Papagayo...Pulses of fresh NE flow are forecast through 
Mon morning.  

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.


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.