Eastern North Pacific Tropical Weather Discussion (Text)

AXPZ20 KNHC 270249

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
248 UTC Thu Apr 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
0230 UTC.


A trough axis extends from 07N80W TO 07N89W to 05N95W to 07N101W 
where scatterometer winds from this evening indicate that the 
northern ITCZ forms and continues to 06N112W to 05N122W to 
05N131W to 03N140W. A southern hemispheric ITCZ axis extends 
from 03.4S107W to 03.4S120W. Scattered moderate to strong 
convection is noted within 120 nm south of the axis between 112W 
and 115W. Scattered strong convection is within 60 nm north of 
the axis between 107W and 110W, and and within 60 nm of the axis
between 117W and 119W. Scattered moderate isolated strong 
convection is within 120 nm south of the axis between 85W and 
90W, within 180 nm north of the axis between 126W and 131W, 
within 60 nm south of the axis between 90W and 97W and within
60 nm of the axis between 138W and 140W.



A tight pressure gradient over the northeast portion of the
area between high pressure ridging that extends southeastward
over the area and the thermal trough across the Gulf of
California is bringing strong to near gale force northwest winds 
just north of the discussion waters east of 125W. Seas generated 
by these winds are in the range of 9 to 12 ft. The northwest 
swell associated with these seas has propagated into the
northeast part of the discussion waters just to the west of
the Baja California Peninsula to near 122W, where 10 to 11 ft
combined seas are observed. Peak seas to 10 ft have reached 
southward to near 20N and west to near 125W. The tight pressure 
gradient will weaken some early this evening, but tighten again
late tonight into Thursday morning, with northwest winds
increasing to the strong category north of about 28N between 
117W and 124W, with generated combined seas of 9 to 12 ft.
These winds will continue through Friday allowing for combined
seas to build some more to around 13 ft north of 29N between 119W
and 121W. Seas to 10 ft will continue to press southward
elsewhere north of 20N between 115W and 129W. The gradient 
should begin to relax late on Friday night, with the area of 
strong northwest to north winds gradually shifting westward as
high pressure just north of the area moves to the northeast.

Gulf of California: Light and variable winds are occurring 
throughout the Gulf, except in the southern sector where the flow
is mainly gentle from the south and southwest in direction. The 
flow will become generally moderate to locally fresh from the 
southwest and west during Friday across just about the entire 
Gulf as the thermal trough becomes more pronounced.

Gulf of Tehuantepec: Gentle to moderate south to southwest flow
will continue through Friday as suggested in the latest
scatterometer data.


Mostly a gentle onshore breeze is expected during the day 
becoming offshore along the coasts at night. Combined seas of 4 
to 5 ft in mixed SW and NW swell are forecast during the next 
several days.


A 1029 mb high pressure system is analyzed at 32N139W, with a 
ridge extending southeastward to near 18N117W. The 1029 mb 
high center will weaken slightly as it moves north-northeast 
through Thursday allowing the present tight gradient over the 
northeast portion to slacken some this evening, but then 
tighten again late tonight through Thursday. This will 
support strong northwest to north winds and seas of 8 to 
11 ft over the northeast portion outside the waters within 
250 nm of Mexico. These conditions will change little through
Friday. Fresh northeast trades are expected to the south of the
ridge axis to zone of the ITCZ, and will maintain seas of 6 to 8
ft to the west of 121W through Thursday, and from 07N to 21N 
west of 136W on Friday. Southern hemispheric cross-equatorial 
swell will produce seas in the range of 7 to 9 ft to reach the 
equator between 106W and 120W on Fri.


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Page last modified: Thursday, 27-Apr-2017 02:49:51 UTC