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.


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 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.

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 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.

REMAINDER OF THE AREA... 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.

$$ GR