AXPZ20 KNHC 171535

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1402 UTC Fri Nov 17 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 1200 UTC surface analysis and satellite imagery through 1500 UTC.


The monsoon trough extends from 09N83W to 10N90W to 08N100W TO 09N125W where it transitions to the intertropical convergence zone, and extends from 09N125W to 11N136W to beyond 08N140W. Scattered moderate convection is noted from 08N to 12N between 114W and 123W. Similar convection is from 12N to 15N between 134W and 136W.



A weak 1018 mb surface high centered near 25N124W is forecast to dissipate within 24 hours. This system will be reinforced by a stronger high pressure from the N on Sat. Under this weather pattern, expect gentle to moderate northerly winds across the offshore waters W of Baja California today, with moderate to fresh NW to N flow, and building seas of 6-7 ft N of 25N Sat morning through late Sun.

Gulf of Tehuantepec: Pulses of strong to near gale force northerly drainage flow, with seas building to a max of 11 ft, are forecast late tonight into early Sat morning, diminishing afterward as the high pressure over the eastern slopes of the Sierra Madre mountains weakens. Another strong cold front will enter the Gulf of Mexico late Sat, followed by strong high pressure building into northeast and central Mexico through Sun. This will support a return of strong gap winds in the Gulf of Tehuantepec by early Sun, reaching gale force early Sun afternoon through Mon morning. Marine guidance indicates winds of 35-40 kt and building seas of 14-15 ft by Sun night.

Gulf of California: Strong high pressure building north of the area over the Great Basin will support fresh to strong NW winds across the northern Gulf of California by mid-day Sat, spreading into the central and southern portions of the gulf late Sat into Sun, before diminishing late Sun. Seas are forecast to build to 6 or 7 ft across the central gulf early on Sun.


Gulf of Papagayo: Moderate to locally fresh NE drainage winds are forecast during the overnight hours through the middle of next week with seas building to 5 ft downstream near 10N87W.

Light and variable winds, and 3 to 5 ft seas, are expected elsewhere to the N of 09N, while moderate to locally fresh southerly winds, and 4 to 7 ft seas, are forecast S of 09N through the middle of next week.


A 1015 mb occluded surface low is centered near 29N132W. The associated cold front enters the forecast waters near 30N128W and extends to 20N135W. An earlier ASCAT pass indicated fresh to strong N winds within about 120 NM in the NW quadrant of the low center. A pair of altimeter passes showed 8 to 10 ft seas in the wake of the front. The low is forecast to move near 28N132W within the next 12 hours while weakening significantly. The front will become stationary later today and gradually dissipate tonight into Sat.

Strong SE to S return flow will develop across the NW waters N of 27N W of 138W by Sat night, in advance of the next cold front forecast to approach the far NW corner of the area Sun night. The front will move slowly with the strong S to SW flow persisting over the NW waters on Mon. At that time, expect fresh to strong winds and seas of 8 to 10 ft covering roughly the waters N of 24N W of 136W.

Farther S and N of the ITCZ/Monsoon trough, expect gentle to moderate trade winds and 4 to 6 ft seas through Sat, with moderate to fresh trades and seas of 6 to 8 ft by Sat evening into Sun.

$$ GR