Tropical Weather Discussion
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AXPZ20 KNHC 270241

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Thu Jul 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.


Hurricane Hilary is centered near 17.1N 114.2W at 27/0300 UTC or
about 415 nm SSW of the southern tip of Baja California moving
WNW at 10 kt. Estimated minimum central pressure is 976 mb.
Hilary has weakened a little. Now, maximum sustained wind speed
is 85 kt with gusts to 105 kt. Additional gradual weakening is
forecast during the next 48 hours. Numerous moderate to strong
convection is within 75 nm N and 45 nm S semicircles of center.
A band of moderate convection is from 15N to 18N between 111W
and 113W. See latest NHC forecast/advisory under AWIPS/WMO
headers MIATCMEP4/WTPZ24 for more details.

Tropical Storm Irwin is centered near 14.9N 123.1W at 27/0300
UTC or about 865 nm WSW of the southern tip of Baja California
moving WSW at 5 kt. Estimated minimum central pressure is 995 mb.
Maximum sustained wind speed is 50 kt with gusts to 60 kt. Irwin
is forecast to move slowly over the open Pacific with little
change in strength during the next 48 hours. Irwin is a sheared
tropical cyclone with numerous moderate to strong convection
within 120 nm W semicircle. See latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMEP5/WTPZ25 for more details.


A tropical wave is along 105W from 05N to 14N moving W at 10-15
kt. Scattered moderate convection is within about 90 nm on
either side of the wave axis.


The monsoon trough extends from 08N79W to 08N90W to 09N100W to
12N110W, then resumes at 10N125W to 07N133W. The ITCZ axis
continues from 07N133W to beyond 07N140W. A cluster of moderate
to isolated strong convection is N of 07N between 82W and 85W.
Scattered moderate convection is from 07N to 11N between 92W and
97W, and from 08N to 11N between 109W and 112W. Isolated
moderate convection is from 06N to 11N between 132W and 137W.



Gentle to moderate NW winds are expected to continue within 120
nm of the Baja California peninsula through Friday. Seas will
maintain 6 to 8 ft as southerly swell associated with Hurricane
Hilary will continue impacting the forecast zones offshore of
Baja California through Friday then remain W of the area during
the weekend. Gentle southerly flow will prevail in the Gulf of
California, and moderate southerly flow across the northern Gulf
of California.

Nocturnal fresh northerly winds are forecast across the Gulf of
Tehuantepec through Friday morning with seas peaking at 8 ft
briefly during the period of strongest winds. Hilary will cross
south of Clarion Island tonight. Fresh to strong winds and seas
of at least 12-14 ft are reaching the island and surrounding
waters. Hilary will remain outside of the offshore forecast
zones Friday and into the upcoming weekend.


Across the Gulf of Papagayo, expect fresh winds each night with
the assistance of the nocturnal drainage flow the next few days,
occasionally building maximum seas to 7 ft in a mix of E wind
waves and long period SW swell.

Gentle to moderate S to SW winds are expected the next few days.
Long period cross-equatorial SW swell will continue to propagate
into the forecast waters through Saturday, reaching the waters
between Ecuador and the Galapagos Islands on Thursday with
building seas of 8-9 ft.

High pressure is located N of the area with a ridge axis
extending across the forecast waters N of 22N. The pressure
gradient between this system and the active zone of tropical
cyclone activity will maintain moderate to fresh N to NE winds W
of 120W through Saturday. An altimeter pass indicated seas up to
9 ft associated with post-tropical cyclone Greg across the west-
central waters from 17N to 21N W of 138W. Long period cross
equatorial SW swell of 8-9 ft will spread across the waters S of
10N and E of 110W, persisting into the weekend.

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