AXPZ20 KNHC 192140

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2140 UTC Sun Nov 19 2017

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 2130 UTC.


Gulf of Tehuantepec Gale Warning: Strong high pressure is surging down eastern Mexico while a cold front is also moving into the SW Gulf of Mexico N of the area. While there have been no recent observations in the Gulf of Tehuantepec, available guidance indicates that northerly strong to minimal gale force winds have commenced. Winds will continue to increase, approaching strong gale force overnight tonight, then will diminish by Mon afternoon as the gradient significantly slackens. Seas will rapidly build to up to 17 ft during the strongest winds tonight. Northerly winds will pulse to fresh to near gale force Mon night, then will diminish to 20 kt or less Tue morning. Northerly flow will then pulse to fresh to strong starting Wed morning with another gale force wind event possible Wed night through Fri night.


The monsoon trough axis extends from 09N76W to 07N91W to 09N106W. The intertropical convergence zone axis extends from 09N106W to 10N114W to 10N130W to 12N140W. Scattered moderate and isolated strong convection is within an area bounded by 10N113W to 13N118W to 11N127W to 07N129W to 04N126W to 06N114W to 10N113W.



Please read the Special Features section above for information regarding the Gulf of Tehuantepec Gale Warning.

A NW to SE oriented ridge just beyond 250 nm seaward will maintain moderate to locally fresh NW flow W of the Baja Peninsula through the evening when the pressure gradient will relax, supporting moderate NW flow later tonight through sunrise Mon. Light N winds winds then are expected through Thu. A trough is forecast to form from the central Baja Peninsula southward, on Thu night and Fri, accompanied by a light W to NW wind shift. Expect seas in the 4 to 7 ft range today, with these conditions resuming again late in the week, with 3 to 5 ft seas during early and mid part of the week.

Gulf of California: Fresh to strong NW winds across the central and northern gulf W of 110W will diminish tonight as the pressure gradient relaxes. Moderate NW flow is then forecast across the entire gulf waters, becoming light by Mon evening. Moderate to locally fresh NW flow will resume across the entire gulf on Tue and Wed, then diminishing Thu through Fri.


Gulf of Papagayo: Moderate to locally fresh NE drainage winds are forecast during the overnight hours tonight and on Mon night, then light drainage flow expected during the overnight hours through Thu night, with moderate to fresh nocturnal drainage resuming on Fri night.

Light and variable winds and 3 to 5 ft seas are expected elsewhere to the N of the monsoon trough, which has been meandering between 09N and 11N. Moderate to locally fresh southerly winds and 4 to 7 ft seas are forecast S of the monsoon trough through the week.


A tight pressure gradient is in place between a dissipating cold front W of 140W and ridging to the E across the northern waters. Associated scattered moderate convection is within an area bounded by 28N132W to 30N132W to 30N140W to 21N140W to 28N132W. The tight pressure gradient is supporting fresh to strong southerly flow in the NW corner of the discussion waters, along with 8 to 10 ft seas. Winds will increase to near gale force with seas also building to 12 ft by early Mon with a lengthening fetch area. The front will dissipate prior to reaching 140W.

Additional cold fronts will approach 140W through the week, but will stall through Wed night as high pressure holds. A weakening front will manage to cross 140W by early Thu with an associated area of large NW swell intruding prior to its arrival. NW swell will build seas to 16 ft near 30N140W by Thu morning. The highest seas will decay through the end of the week, but the edge of seas of 8 ft or greater will manage to stretch across the waters N of 10N and W of 125W by Fri morning.

Elsewhere, fresh to locally strong trades are supporting seas to 8 ft within an area bounded by 14N129W to 16N132W to 15N137W to 12N135W to 11N131W to 12N128W to 14N129W. Trades will diminish slightly later tonight allowing for seas to subside to less than 8 ft.

$$ Lewitsky