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.

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