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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 270241
TWDEP 

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.

...SPECIAL FEATURES... 

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.

...TROPICAL WAVES... 

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. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

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.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

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.   

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, 
COLOMBIA, AND WITHIN 750 NM OF ECUADOR... 

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. 

REMAINDER OF THE AREA... 
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. 

$$
GR