AXPZ20 KNHC 251511

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1511 UTC Thu May 25 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 axis extends from 08N102W to 15N95W to low pressure near 13N101W to 08N115W to 09N132W. The intertropical convergence zone axis extends from 09N132W to 07N140W. Scattered moderate to strong convection is from 03N to 09N E of 80W. Scattered moderate and isolated strong convection is from 05N to 08N between 85W and 91W, and also from 06N to 10N between 118W and 129W. Scattered moderate convection is from 06N to 08N between 134W and 138W.

In addition, scattered moderate and isolated strong convection is within 300 nm of the center of the low pressure area near 13N101W, except within 420 nm in the NE quadrant.



A weak high pressure ridge snakes into the area from the NW and then W along about 25N, with the associated gradient supporting generally moderate NW winds across the Baja California Peninsula waters. Light to gentle NW to N winds are noted elsewhere over the Mexican offshore waters to Acapulco. Seas are in the 4 to 5 ft range in mixed SW and NW swell across these waters, except across the Michoacan through Chiapas offshore waters where winds and seas are higher. This is due to 1008 mb low pressure located near 13N101W. Fresh to strong S to SW winds and seas in the 8 to 10 ft range are occurring on the SE side of the low with 4 to 7 ft seas elsewhere across the two offshore zones. The low is forecast to gradually dissipate through the next 12 to 24 hours, allowing for associated winds and seas to subside. The pressure gradient will tighten slightly to the N of 20N through Friday as the ridge builds modestly into the region, with winds and seas increasing slightly across those areas. Gentle to moderate SE winds occurring elsewhere between Tehuantepec and offshore of Acapulco will gradually weaken and veer SW to W through Friday.

In the Gulf of California, mainly light to gentle variable winds are expected through the day except in the northern Gulf, with seas of 2 ft or less, except 3 to 5 ft near the entrance to the Gulf. Low pressure just to the N of the area over SW Arizona will linger through the end of the week. A trough extending S to SW from the low to Baja California Norte will linger as well. Fresh to nearly gale force SW to W winds have developed to the SE side of the trough, and will persist through Friday night. The winds are enhanced through the gaps in the higher terrain of Baja. Seas will also build to 6 to 8 ft tonight on the SE side of the trough.


Gentle SW to W winds prevail between the Papagayo region and Tehuantepec, with seas of 4 to 6 ft in SW swell. Expect NW to W monsoonal winds to spread across the coastal waters through Friday as a tropical wave moves across the area through Friday. Nocturnal offshore winds will pulse to fresh levels near the Gulf of Papagayo by Saturday night, behind the wave, and again on Sunday night. Moderate SW winds will continue to the S of 09N through Thursday night. A few pulses of SW swell are forecast to propagate across the area through the next several days, occasionally building seas to 7 ft. Otherwise, little change is anticipated through the upcoming weekend and early next week.


A weak ridge extends from 28N140W southeastward through 21N131W to 25N116W. The ridge is slowly shifting SE as a weak trough from 30N126W to 25N134W, and a cold front along and N of 30N are sinking southward. Moderate northerly winds follow the trough and front in the northern waters, with long period N swell producing seas of 7 to 9 ft across the area from 29N to 32N between 124W and 136W today, before subsiding to less than 8 ft Friday evening. Elsewhere N of the deep tropics, the weak ridge will maintain moderate trade winds S of 18N, with seas of 5 to 7 ft expected through Friday. High pressure NW to N of the area will build southward by the end of the weekend and into early next week, supporting increasing trades to moderate to fresh levels and resultant seas of 5 to 8 ft across the waters N of the convergence zone.