AXPZ20 KNHC 010228

0405 UTC WED JUN 01 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 0000 UTC surface analysis and satellite imagery through 0300 UTC.


Tropical wave is moving off Costa Rica. Scattered convection is noted from 05N to 08N between 87W and 89W.

Tropical wave is along 100W from 06N to !3N. This wave is moving into an area of strong southwest winds, as noted in earlier scatterometer data. Low level convergence due to these winds is supporting a large area of scattered to numerous showerS and thunderstorms from 10N to 12N between 98W and 101W.


The monsoon trough extends from 10N85W to 11N100W to complex low pressure near 10N113W to 08N121W. The ITCZ reaches from 08N121W to 07N140W. Scattered moderate to strong convection is noted within 180 nm south of the monsoon trough axis between 85W and 100W, and between 110W and 118W.


North of 15N east of 120W - an upper trough continues to move across the northern reaches of the Gulf of California. Related upper dynamics is supporting a train of showers and thunderstorms into Todos Santos in the Pacific coast of Baja California Sur then across the peninsula to the southern Gulf of California, although this appears to be diminishing. Altimeter data from this morning indicated seas 8 to 9 ft south of 20N, in predominantly southwest swell mixed with northwest swell. This swell is expected to decay below 8 ft through Wednesday.

South of 15N east of 120W - successive scatterometer passes since last night have indicated a surge of southwest winds into the monsoon trough from 06N to 09N between roughly 90W and 95W. Altimeter data from this area has been showing concurrent wave heights of 8 to 10 ft, with some contribution of southwest swell. The winds are to the east of a pair of elongated weak low pressure areas along the monsoon trough farther west near 110W and 116W. The winds are expected to diminish after Wednesday as the low pressure areas drift farther west, allowing seas and thunderstorm activity to diminish as well.

West of 120W - A cold front is approaching the waters north of 25N to the east of 140W. Although strong winds are noted just ahead of this front to around 138W, the front will weaken and stall before crossing into the discussion area through tonight. Wave heights of 6 to 7 ft will impact the waters north of 25N and west of 137W through Wednesday related to shorter period swell generated along the front. Otherwise, broad ridging will prevail across the waters north of 15N and west of 120W. Farther south into the tropics, a pair of weak low pressure centered along the monsoon trough and near 110W and 116W respectively will gradually merge and deepen through Wednesday, crossing 120W by late Friday. No tropical cyclone development is expected through mid week, but the merged low may deepen further by late week according to some model output. Uncertainty remains regarding the expect track and intensity of this system at this time, but most guidance keeps the low pressure system south of 15N moving west through late week.

$$ Christensen