AXPZ20 KNHC 250241

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 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 0000 UTC surface analysis and satellite imagery through 0215 UTC.


The Monsoon Trough axis extends from 09N79W to a 1008 mb low at 14N94W to 13N104W to another 1008 mb low at 09N109W to 09N124W. ITCZ axis extends from 09N124W to 08N134W to 07N140W. Scattered moderate to numerous strong convection is within 180 nm south of the axis between 94W and 105W. Scattered moderate to isolated strong convection is within 120 nm of the axis between 125W and 128W, and also within 60 nm of the axis between 121W and 125W. Scattered moderate convection is within 60 nm of the axis between 113W and 115W.



Rather weak high pressure is present over the area, with the associated gradient supporting generally moderate northwest winds prevailing across the Baja California Peninsula waters. Light to gentle NW to N winds are noted elsewhere over the Mexican offshore waters. Seas are in the 4 to 5 ft range in mixed SW and NW swell across these waters, with slightly higher seas of 5 to 6 ft south of Puerto Angel. The pressure gradient will tighten slightly to the north of 20N through Friday as the ridge builds some into the region, with winds and seas increasing slightly.

In the Gulf of California, mainly light to gentle variable winds are expected through Thursday 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 is presently deepening quite rapidly just to the north of the area over SW Arizona, and should remain pretty low through at least Thursday night. A trough will extend from the low across the northern Gulf to Baja California Norte through Friday. Fresh to strong southwest to west are expected to develop shortly to the southeast of the trough tonight, and then again on Thursday night into Friday as winds become enhanced through the gaps in the higher terrain of Baja. Seas are expected to build to around or to 8 ft each night during the nocturnal wind max.

S of 16N including the Gulf of Tehuantepec, broad and ill-defined low pressure has persisted across the offshore waters SW of Tehuantepec the past few days, and continues to gradually drift westward. Last visible satellite imagery showed the presence of another weak low pressure to the south-southeast of the Gulf of Tehuantepec near 14N94W. The low is on the northeast edge of the large clusters of very deep convection described above under ITCZ/Monsoon Trough. This low is expected to remain about stationary through the next 24 hours, and perhaps dissipate thereafter. Another weak low is noted to the west of this deep convection near 09N109W moving westward. Models depict this low to track more in a northwesterly direction beginning late on Thursday and through Friday while beginning to slow down as ridging to its NW builds to the SE. Gentle to moderate SE winds occurring between Tehuantepec and offshore of Acapulco will gradually weaken and veer SW to W through Friday.


Gentle to moderate E to SE winds prevail between the Papagayo region and Tehuantepec, with seas of 4 to 5 ft in SW swell. Expect these conditions to continue through this evening before gentle to moderate SW to W monsoonal winds spread N of 09N and into the coastal waters through Friday. Nocturnal offshore winds will pulse to fresh levels near the Gulf of Papagayo by Saturday night, and again on Sunday night. Moderate SW winds will continue to the south of 09N through Thursday night. A new pulse of SW swell is progged to arrive Thursday through late Friday. Otherwise, little change is anticipated through the upcoming weekend.


A weak ridge extends from 32N140W southeastward to near 17N113W. The ridge will change little through Thursday as a weak cold front moves across the northeast portion of the area, then build some southeastward Friday through Saturday once the front the exits the area. A set of long period NW swell producing max seas of 8 to 9 ft is forecast to approach the area from 31N to 32N between 125W and 135W on Thursday, before subsiding to less than 8 ft late Friday afternoon. 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.

$$ Aguirre