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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 282205 RRA

2205 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 1800 UTC surface analysis and satellite imagery through
2145 UTC.


The monsoon trough axis extends from 10N84W to 11N96W to 13N110W
to low pressure near 10N122W 1009 mb to 07N126W. ITCZ extends
from 07N126W to beyond 05N140W. Scattered moderate to isolated
strong convection is within 120 nm s of the axis between 93W
and 97W, and south of the axis within 30 nm of a line from
09.5N106W to 09N111W. Scattered moderate convection is within
60 nm of the axis west of 136W. 


High pressure centered N of the area extends a ridge
southeastward to 32N133W to 25N127W to near 20N120W. High
pressure covers the area north of 15N and west of 115W. A weak
low of 1009 mb is analyzed near 10N122W. Widely scattered
showers and isolated thunderstorms are noted mainly within 120
nm east semicircle of low. Global model guidance continues to
keep the low in the same general area through Sunday morning
with some development before it begins to lift in a north to
northeasterly direction through Monday. Strong south to
southwest winds are expected to to the southeast of the low from
10N to 12N between 117W and 120W on Sunday with seas building to
10 feet. A tight pressure gradient between the low and the ridge
over the northern and central waters should allow for strong
northeast winds to develop in the northwest quadrant of the low
on Sunday with seas of 8 to 9 ft. The low is forecast to weaken
Sunday night and Monday with associated winds decreasing to 20
kt and seas of 8 ft in south to southwest mixed with a secondary
swell component from the north over an area roughly south of 16N
between 114W and 127W. 

East of 125W...satellite water vapor imagery shows plentiful
deep atmospheric moisture present underneath a mid-level ridge
roughly along 14N. The southern portion of an upper level trough
that stretches from central Baja California to near 12N126W is
providing lift for the deep moisture. This has resulted in the
development of clusters of scattered moderate to isolated strong
convection near and south of the monsoon trough segment between
105W and 111W. The trough is forecast to shift east of the area
Sunday. Ascat data from this afternoon depicted an area of fresh
northeast winds west of 136W between 09N-12N, and moderate
trades N of the convergence zone west of 125W. Mainly gentle
winds prevail elsewhere across the basin. Elsewhere, near gale
force N-NW winds along the California coast have produced an
area of 7-8 ft N swell in north-central waters between 123W and
129W. Cross-equatorial S-SW swell will affect the area south of
the equator between 104W and 120W. The swell is forecast to
merge with the area of elevated sea heights associated with the
low near 10N122W to produce a fairly large area of 6-8 ft seas
in south-central waters by late Sunday  Mostly benign marine
conditions are expected to prevail across the remainder of the
forecast area through Tuesday.