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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 280300

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 was downgraded to a tropical storm at 28/0300 
UTC. At this time, Hilary is centered near 18.3N 117.3W or about 
485 nm SW of the southern tip of Baja California moving WNW at 7 
kt. Estimated minimum central pressure is 992 mb. Maximum 
sustained wind speed is 60 kt with gusts to 75 kt. Numerous 
moderate convection is within 60 nm S quadrant. See latest NHC 
forecast/ advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 for 
more details.

Tropical Storm Irwin is centered near 14.9N 124.6W at 28/0300 
UTC or about 950 nm WSW of the southern tip of Baja California 
moving W at 2 kt. Estimated minimum central pressure is 1000 mb. 
Maximum sustained wind speed is 50 kt with gusts to 60 kt. Some 
fluctuations in intensity are likely the rest of today and 
tomorrow. Numerous moderate and scattered strong convection is 
within 90 nm of center, except NW quadrant. See latest NHC 
forecast/ advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 for 
more details.


The monsoon trough extends from 10N86W to 08N95W to 09N105W to 
12N110W. The ITCZ axis extends from 10N132W to 07N140W. 
Scattered moderate isolated strong convection is within 150 nm 
south of trough between 88W and 92W, and within 150 nm north of 
trough between 94W and 97W. Scattered moderate convection is 
near the western end of the monsoon trough from 08N to 14N 
between 108W and 115W. This convective activity was previously 
associated with a tropical wave. Scattered moderate isolated 
strong convection is on either side of the ITCZ axis from 07N to 
10N W of 132W.


Gentle to moderate NW winds are expected to continue within 120 
nm of the Baja California peninsula through Friday. Seas of at 
least 8 ft associated with tropical cyclone Hilary will continue 
to impact the forecast zones offshore of Baja California through 
the upcoming weekend. As Hilary moves away from this area, 
expect moderate to fresh NW winds just off the coast of Baja 
California, and across the southern Gulf of California Sun night 
into Mon. A ridge will build between the Baja California 
Peninsula and tropical cyclones Hilary and Irwin.

Nocturnal fresh northerly winds are forecast across the Gulf of 
Tehuantepec through Friday morning with seas peaking around 8 ft 
during the period of strongest winds. Cross equatorial long 
period southerly swell with seas of 7-8 ft will reach the 
offshore waters between the Gulf of Tehuantepec and Cabo 
Corrientes on Sun, and the waters between Los Cabos and Cabo 
Corrientes on Mon. 

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 7 to 8 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 tonight with building 
seas of 8-9 ft.

High pressure is located N of the area with a ridge axis 
extending across the northern forecast waters N of 20N. 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. 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.