AXPZ20 KNHC 260333

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Wed Jul 26 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 16.0N 109.8W at 26/0300 UTC moving WNW at 10 kt. Estimated minimum central pressure is 973 mb. Maximum sustained wind speed is 90 kt with gusts to 110 kt. Numerous moderate to strong convection is seen within 90 nm in the NE semicircle of the system. Numerous moderate isolated strong convection is noted elsewhere within 75 nm SW semicircle. A band of moderate convection is to the NW of the center from 16N to 19N between 109W and 111.5W. See latest NHC forecast/ advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 for more details.

Hurricane Irwin is centered near 16.1N 120.9W at 26/0300 UTC moving W at 7 kt. Estimated minimum central pressure is 980 mb. Maximum sustained wind speed is 80 kt with gusts to 100 kt. Irwin is a small cyclone with numerous moderate to scattered strong convection noted within 60 nm in the W and 30 nm in the E semicircles. Irwin is expected to interact with hurricane Hilary later this week. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 for more details.

Tropical Depression Greg is centered near 17.2N 138.8W at 26/0300 UTC moving NW at 12 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained winds are now 30 kt with gusts to 40 kt. Additional weakening is expected during the next couple of days, and Greg is forecast to degenerate into a remnant low by Wednesday night. Convective activity associated with Greg continues to decrease with scattered moderate isolated strong convection noted within 60 nm in the W semicircle. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 for more details.


A tropical wave is along 100W N of 05N moving W at 10-15 kt. Convection is limited near the wave axis.


The monsoon trough extends from 08N78W across western Panama and southern Costa Rica to 09N84W to 09N90W to 08N96W to 13N105W. Scattered moderate isolated strong convection is N of 07N E of 83W.



Gentle to moderate NW winds off the Baja California peninsula are expected to continue through Wednesday, as high pressure remains centered N-NW of the area. Seas will remain generally 4 to 6 ft in mixed swell through Wednesday. Thereafter, Hurricane Hilary will begin impacting the forecast zones offshore of Baja California through Friday with increasing winds and building seas in mainly southerly swell. This could continue during the upcoming 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 Thursday night into Friday morning. Hilary is expected to impact the offshore waters beyond 200 nm off the coasts of Michoacan, Colima and Jalisco through tonight, then pass S of the Revillagigedo Islands early Wednesday, and south of Clarion Island early Thursday. A couple of altimeter passes provided observations of seas in the 7-9 ft range near the coasts of of Michoacan, Colima and Jalisco. Seas of at least 8 ft associated with Hilary are forecast to reach the waters between 107W and 115W in the vicinity of Cabo San Lucas Wednesday into Thursday.


Across the Gulf of Papagayo, expect fresh winds each night with the assistance of the nocturnal drainage flow through the week, occasionally building max 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 across the forecast zones the next several days. Long period cross-equatorial SW swell generating 5-7 ft seas will continue to propagate into the forecast waters through Wednesday. Another set of cross- equatorial long period SW swell of 6 to 9 ft will reach the waters between Ecuador and the Galapagos Islands Thursday, and continue through the upcoming weekend. Seas of 6-8 ft will reach the offshore waters of Central America on Friday.


High pressure is located N of the area with a ridge axis that extends across the forecast waters north of 20N. The pressure gradient between this system and the active zone of tropical cyclones between 13N and 19N will maintain moderate to fresh fresh N to NE winds W of 130W through Thursday. On this day, cross equatorial SW swell of 8 to 9 ft will spread across the waters south of 10N and east of 110W, persisting into the weekend.