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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 251002

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Tue Jul 25 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 0600 UTC surface analysis and satellite imagery through 
0900 UTC.


The Eastern Pacific region remains very active with three 
tropical cyclones along 15N at 0300 UTC: from east to west, 
Hurricane Hilary, Hurricane Irwin and Tropical Storm Greg. 

Hurricane Hilary is centered near 15.3N 106.7W, moving WNW at 9 
kt. Estimated minimum central pressure is 975mb. Maximum 
sustained winds are 90 kt with gusts to 110 kt. Numerous 
moderate to strong convection is within 120 nm of the center. 
Continued strengthening is forecast during the next 24 hours, 
and Hilary may become a major hurricane later today or tonight 
as it continues on a WNW track about 200 to 250 nm west of the 
Mexican coast for the next couple of days. See the latest NHC 
forecast/advisory under AWIPS/WMO headers MIATCMEP4 WTPZ24 for 
more details.

Hurricane Irwin is centered near 15.5N 118.7W, moving WNW at 4 
kt with a minimum central pressure of 991 mb. Maximum sustained 
winds are 65 kt with gusts to 80 kt. Numerous moderate to strong 
convection is within 105 nm of the center. Irwin will remain in 
relatively close proximity to Hilary the next several days, with 
little change in intensity. Model guidance indicates a complex 
binary interaction between the two hurricanes may occur. See the 
latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5 
WTPZ25 for more details.

Tropical Storm Greg is centered near 15.2N 135.7W, moving WNW at 
8 kt. Estimated minimum central pressure is 1003 mb. Maximum 
sustained winds are 40 kt with gusts to 50 kt. Scattered 
moderate isolated strong convection is within 120 nm NW of the 
center. Greg is expected to remain a minimal tropical storm for 
the next 24 hours, then weaken to a tropical depression as it 
approaches 140W Wed. See the latest NHC forecast/advisory under 
AWIPS/WMO headers MIATCMEP2 WTPZ22 for more details.


A tropical wave is along 96W north of 06N moving west at 15 kt. 
Convection associated with the wave is well east of the wave 
axis, along 95W to 96W. 


The monsoon trough is analyzed east of the tropical cyclone 
activity from 08N78W to 10N96W. The ITCZ extends SW of TS Greg 
from 12N136W to 10N140W. Scattered moderate isolated strong 
convection is centered within 90 nm of 11N96W.



Gentle to moderate NW winds off the Baja California peninsula 
are expected to continue through mid-week, as high pressure 
remains centered N of the area. Seas will remain 4 to 6 ft in 
mixed swell through Wednesday. Gentle southerly flow will 
prevail in the Gulf of California, and moderate southerly flow 
over the northern Gulf. Large southerly swell from Hilary may 
reach the waters west of Baja California Thursday and Friday.

Nocturnal fresh northerly winds are forecast over the Gulf of 
Tehuantepec Tuesday through Thursday nights. Hilary is expected 
to impact the offshore waters beyond 200 nm off the coasts of 
Guerrero, Michoacan, Colima and Jalisco through Tue, then pass 
south of the Revillagigedo Islands Wed as a major hurricane.
Seas of at least 8 ft associated with Hilary are forecast to 
reach the waters between Los Cabos and Cabo Corrientes on 


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 near 8 ft in a mix of east wind
waves and long period southwest swell.

Gentle to moderate S to SW winds are expected across the forecast
zones the next several days. Long period cross-equatorial SW 
swell creating 5-7 ft seas will continue to propagate into the 
forecast waters through mid week. Another set of cross-equatorial
long period SW swell of 6 to 9 ft will reach the waters between 
Ecuador and the Galapagos Islands late Wednesday, and the coast 
of Central America on Thursday. 


High pressure is located north of 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 14N and 20N will maintain fresh N to NE winds W 
of 125W through mid-week. By Thursday, cross equatorial SW swell 
of 8 to 9 ft will spread over the waters south of 10N and east 
of 110W, persisting into the weekend.