AXPZ20 KNHC 281002

1005 UTC SAT MAY 28 2016

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 0600 UTC surface analysis and satellite imagery through 0830 UTC.


The monsoon trough passes through 10N85W to 09N96W, from 12N107W to 12N110W, to a 1009 mb low pressure center that is near 10N122W, and to 06N129W. The ITCZ continues from 06N129W to 06N135W, beyond 05N140W. Convective precipitation: scattered moderate to isolated strong within 150 NM to the south of the monsoon trough between 86W and 102W, and from 11N to 16N between 92W and 95W. Scattered moderate to isolated strong within 120 nm to the east of the 1009 mb low pressure center, from 07N to 08N between 107W and 109W, from 08N to 09N between 112W and 113W, and within 90 nm to the north of the ITCZ between 133w and 138w.


A surface ridge is along 19N112W to 22N121W to 26N130W beyond 32N136W. Surface high pressure covers the eastern Pacific Ocean from 15N northward from 118W westward. ASCAT winds have been showing fresh north to northeast winds from the ITCZ to 22N from 118W westward. Gale-force northerly winds that are to the north of the area near the California coast are expected to produce an area sea heights of 8 feet to 9 feet. The 8 foot to 9 foot sea heights are forecast to reach as far as 28N between 122W and 129W during the next few days.

Global models are persistent in depicting a broad and fairly weak area of low pressure in the central waters near 10N122W. The models suggest some development of the low pressure center beginning on Saturday as the low remains in a col region between two anticyclones...one centered near 12N135W
...and the other near 15N106W. A tight surface pressure gradient is forecast to develop between the low pressure center and the 19N112W to 32N136W surface ridge, into Saturday. The surface pressure gradient will lead to fresh northeast winds in the NW quadrant of the low pressure center, with seas building to 8 to 9 feet by early Sunday morning. The low is forecast by a consensus of the model guidance to meander in the area from 11N to 13N between 121W and 122W on Saturday and Sunday, with little change in intensity. It is possible that an active eastern segment of the monsoon trough may spawn a weak low pressure center near 90W on Saturday.

Cross-equatorial south to southwest swell, and 8 foot to 9 foot sea heights will start to affect the area from 01S southward between 108W and 120W. Those conditions will merge with the area of 8 foot to 9 foot sea heights that will start to the north of the low pressure center that will be near 11N122W. The area that will be affected during the next 48 hours will be from 17N southward between 118W and 138w.

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