Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 270244

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Sat May 27 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.


A tropical wave has a tilted southeast to northwest axis 
extending from 05N85W to 12N88W moving westward at about 15 kt. 
This wave earlier was quite active with widespread shower and 
thunderstorm activity to its east. However, over the past few 
hours the shower and thunderstorm has diminished. The wave 
remains embedded within a large are of deep atmospheric moisture 
per latest TPW animation. A nearly 90 nm wide cyclonic swirl of 
low and mid level clouds is observed on satellite imagery along 
the northern portion of the wave near 11N88W. Isolated showers 
and weak isolated thunderstorms are located within this swirl. 
Scattered showers and thunderstorms are diminishing to the east 
of the wave axis from 05N to 09N between 83W and 87W. The flow
aloft to the east of the wave remains rather diffluent, and this
will be favorable to support new development of shower and
thunderstorm activity late tonight into early on Saturday.
The wave is forecast to continue westward during the next 48 
hours, and become embedded within a large area of expected broad 
low pressure south of the southern coast of Mexico early next 

A tropical wave has an axis north of 07N along 93W/94W moving 
westward around 10 kt. Scattered showers and isolated 
thunderstorms are noted within 60 nm east of the wave axis from 
07N to 11.5N.
This activity is presently diminishing. Guidance suggests that 
this wave will continue on a west to west-northwest motion 
through the weekend, with part of it brushing the southern 
portion of Mexico, and the remainder staying offshore the coast.


The Monsoon trough axis extends from 10N96W to 11.5N104W to
11N111W to 09N120W. The ITCZ axis extends from 09N120W to beyond
08N140W. Scattered moderate convection is within 120 nm south of
the axis between 134W and 137W, also within 60 nm south of the 
axis between 113W and 115W and within 60 nm north of the axis
west of 138W.



A surface trough extends from a 1003 mb low over southeast
Nevada south-southeastward to across northern portion of
the Gulf of California, and to just inland Baja California south
to just northwest of La Paz. The pressure gradient between this 
low and higher pressure near Guadalajara is producing strong 
southwest to west winds south of the low to 30N over the 
northern Gulf of California. These winds are likely supporting 
seas to 8 ft over this area. The winds are expected to continue 
through early Saturday before the low weakens and winds diminish.
The pressure gradient between the trough over Baja California 
and higher pressures northwest of the region will support fresh 
northwest winds within about 90 nm of the west coast of Baja 
California through early next week. Occasionally strong winds 
will be possible very near the coast in the afternoons. 
Otherwise, mainly moderate northwest winds are expected west of 
Baja California.

Elsewhere, A tropical wave moving south of southern Mexico will
support scattered to numerous showers and thunderstorms the next
couple of days. Mainly gentle to moderate winds are occurring 
over the offshore waters of Mexico south of the Baja California 
with seas of 4 to 6 ft. These winds and seas are expected to 
prevail for the next several days. 


The eastern portion of the Monsoon Trough is forecast to 
become re-established over the eastern portion of the discussion
area late in the weekend or early next week once the tropical
wave along 05N85W to 12N88W progresses further to west away from
the Central America. Otherwise, mainly light to gentle winds 
will prevail north of about 08N, with seas of 4 to 6 ft. To the 
south 09N moderate to fresh south to southwest winds can be 
expected with seas of about 5 to 7 ft in a southwest swell. 


A storm system northeast of the discussion area has been causing
a weak pressure pattern over the northern waters north of 20N and
west of the Mexico offshore waters. A frontal trough is moving 
across the northeast waters from 32N118W to near 24N130W. This
is keeping a rather weak pressure gradient in place resulting 
in mainly gentle to moderate winds over these waters with seas 
of 5 to 7 ft. Winds to the south of 20N are a little stronger, 
with moderate to locally fresh northeast winds from the 
ITCZ/monsoon trough axis to 20N, and moderate and southerly winds
to the south of these axes. A weak ridge is forecast to build 
over the northwestern waters near 30N133W over the weekend and 
meander over the area into early next week which will continue to
support gentle to moderate winds over the northern waters west 
of the Mexico offshore waters. As this ridge develops, winds over
the waters south of 20N and north of the ITCZ and Monsoon Trough
will increase slightly resulting in combined seas to near 8 ft 
over these waters by early next week. 


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Page last modified: Saturday, 27-May-2017 02:44:56 UTC