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Eastern North Pacific Tropical Weather Discussion

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 

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 



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