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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 151545

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1458 UTC Mon Oct 15 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.


The center of newly named Tropical Storm Tara is located near 
17.6N 104.4W at 15/1500 UTC or 80 nm S of Manzanillo Mexico 
drifting WNW or 295 degrees at 1 kt. Estimated minimum central 
pressure is 1001 mb. Maximum sustained wind speed is 40 kt with 
gusts to 50 kt. Numerous moderate to strong convection is noted
within 120 nm NW and 60 nm SE semicircles. On the forecast 
track, the center of Tara is expected to remain near or just 
offshore of the southwestern coast of Mexico during the next 
couple of days. Slow strengthening is forecast during the next 
few days. See latest NHC forecast/advisory under AWIPS/WMO 
headers MIATCPEP2/WTPZ32 KNHC for more details.

Gulf of California: A Gale Warning is in effect for the northern
Gulf of California through this evening. Strong to near gale 
force NW winds will rapidly develop N of 27N in response to 
robust high pressure building over the Great Basin of the United 
States. Frequent gusts to gale force are also expected N of 30N, 
with seas building to 9 or 10 ft. These marine conditions will 
persist through Tue, but mainly N of 29N. 


The monsoon trough extends from a 1007 mb low pressure centered 
over the SW Caribbean near 15N82W, then across Nicaragua to near
12N87W to 15N97W. Another segment of the monsoon trough stretches
from 14N106W to 10N120W to 11N133W to 09N140W. A cluster of 
moderate to scattered strong convection is seen over the Gulf of
Tehuantepec. Scattered moderate isolated strong convection is N 
of 10N between 85W-93W, from 11N-14N between 98W-111W, from 09N- 
12N between 111W-117W, and within 120 nm N of trough between 



A ridge will continue to dominate the offshore waters W of Baja 
California Peninsula producing mainly gentle to moderate NW to N
winds, and seas generally in the 4 to 6 ft range. Seas are
forecast to increase a foot or so by the end of the forecast 
period as mixed swell generated by Tropical Storm Tara arrives. 

Gulf of Tehuantepec: Next gap wind event is forecast to start 
early on Wed with seas rapidly building to 10 ft by Wed 
afternoon. This event will be associated with a ridge building
behind a cold front across the eastern slopes of Sierra Madre 
Mountains in Mexico and the western Gulf of Mexico.


Moderate to fresh SW monsoonal flow will continue across the 
region through Tue, with showers and thunderstorms expected to 
continue along the Pacific coast of Central America. Long period 
cross-equatorial SW swell will maintain 5 to 8 ft seas across the
forecast area during this time frame. By Tue night and Wed, 
marine guidance suggests an increase in winds and seas across the
offshore waters from Costa Rica to Guatemala. This appears to be
associated with a broad area of low pressure moving from the SW 
Caribbean into Central America during this time frame. 


A 1022 mb high pressure located N of area near 35N127W extends a
ridge across the northern forecast waters producing light to 
gentle winds N of 20N, and gentle to moderate winds S of 20N and 
N of the monsoon trough. The next cold front will approach the 
far NW corner of the discussion area by this evening. Fresh to 
strong southerly winds and seas to 9 ft are forecasted ahead of 
the front. The front will reach a position from 30N139W to 
28N140W on Tue morning, and from 30N138W to 26N140W on Wed
morning while weakening. Long period NW swell will follow the 
front building seas of 8-10 ft.

Satellite-derived wind and altimeter data confirmed the presence
of moderate to fresh monsoonal flow from 05N to 13N between 100W
and 110W, and 05N and 10N between 110W and 125W, with an 
associated area of seas of 7 to 9 ft in long period SW swell.