AXPZ20 KNHC 292202

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2205 UTC Mon May 29 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 2145 UTC.


The Monsoon Trough axis extends from a low in NW Colombia near 09N75W to 10N84W to a 1009 mb low pressure near 13N100W to 11N113W to 07N124W. The ITCZ axis then continues from 07N124W to beyond 06N140W. Scattered moderate to isolated strong convection is noted from 04N to 08N between 77W and 81W. Scattered moderate convection is within 60 nm south of the axis between 102W and 105W, between 107W and 110W, and also within 60 nm north of the axis between 115W and 118W.



Moderate to fresh northwest winds continue to prevail west of the Gulf of California this morning, supported by high pressure to the west and surface troughs over Baja California and mainland Mexico. The high will retrograde westward tonight, allowing winds to relax to mainly moderate east of Baja California through Tuesday morning. On Tuesday, models continue to forecast low pressure to deepen over the interior portion of the western United States. The combination of this and high pressure present to the west of the Baja California will tighten the pressure gradient just west and northwest of Baja California Norte, resulting in fresh northwest winds and combined seas of 7 to 9 ft in northwest swell north of 29N between 120W and 126W beginning on Tuesday afternoon, and spreading southward to neat 27N between 119W and 124W by Wednesday afternoon.

Mainly light to gentle southeast to south winds are expected over the Gulf of California through early Tuesday, then increase to gentle to moderate winds Tuesday night and Wednesday. Seas will be in the range of 1 to 2 ft, except for slightly higher seas of 3 to 4 ft over the entrance to the Gulf of California.

Elsewhere, a 1009 mb low centered near 13N100W is associated with a broad area of low pressure that is located to the south of southern Mexico. This area of low pressure will slowly lift northward through Wednesday. Given that the atmosphere surrounding this low pressure is very moist as observed in TPW animated imagery and very unstable at the time, expect clusters of scattered showers and thunderstorms to persist along and just offshore the coast of southeastern Mexico, including the Gulf of Tehuantepec. As a result, heavy rainfall and localized flooding will be possible over these coastal sections through this week. Gusty winds and seas briefly reaching to 8 ft will be possible with the strongest of the shower and thunderstorm activity. Gradual development of the low pressure is possible as well during the week. Otherwise, mainly light to gentle winds and seas of 5 to 7 ft will prevail over the Mexican offshore waters south of the Baja California Peninsula through Wednesday.


Moisture southerly flow associated with the Monsoon Trough axis that stretches from NW Colombia to near 10N90W will continue to provide support for scattered to numerous showers and thunderstorms mainly north of 04N. Some of this activity may contain strong gusty winds and rough seas. Light to gentle winds will prevail north of the trough axis with 4 to 6 ft seas. Mainly moderate south to southwest winds are expected south of the trough axis with seas of 5 to 7 ft.


High pressure of 1025 mb is centered near 30N133W with a ridge extending southeastward to 26N126W and to near 20N118W. High pressure covers the area north of 16N and west of 117W. The associated gradient between the ridge and lower pressure to the south in the deep tropics is supporting fresh northeast trades from 07N to 15N west of 133W, with seas of 7 to 9 ft in mixed northeast and southeast swell. This area of winds and seas is forecast to gradually shrink through Wednesday as the ridge retreats westward. Seas of 6 to 8 ft in mixed northeast and southeast swell will linger within the same general area by Wednesday. Gentle to moderate trade winds will continue over the remainder of the northwestern waters through Wednesday with 5 to 7 ft seas. Fresh northwest winds are forecast to develop north of 27N and east of 125W tonight as the pressure gradient between low pressure deepening inland over the SW United States and high pressure over the northwest and north/central waters tightens. These winds will support 7 to 9 ft seas over that area through Wednesday night.

$$ Aguirre