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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 240955

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 UTC Mon Jul 24 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: from east to west, Hurricane Hilary, Tropical 
Storm Irwin and Tropical Storm Greg. So far in July, five named 
storms have developed.

Hurricane Hilary is centered about 300 nm S of Manzanillo Mexico 
near 14.0N 103.8W at 2 am PDT, moving WNW at 7 kt. Estimated 
minimum central pressure is 990 mb. Maximum sustained winds have 
increased to 65 kt with gusts to 80 kt. Numerous moderate 
scattered strong convection is within 120 nm of the center. 
Conditions are favorable for significant strengthening during 
the next 24 to 48 hours, and Hilary is forcast to become a major 
hurricane on Tuesday 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.

Tropical Storm Irwin is centered near 14.8N 117.4W at 2 am PDT, 
moving W at 4 kt with a minimum central pressure of 1001 mb. 
Maximum sustained winds remain 45 kt with gusts to 55 kt. 
Scattered moderate isolated strong convection is from 12N to 17N 
between 114W and 119W. Irwin will remain in relatively close 
proximity to Hilary the next few days. Gradual strengthening is 
expected during the next 48 hours, and Irwin is forecast to 
become a minimal hurricane in about 24 hours. See the latest NHC 
forecast/advisory under AWIPS/WMO headers MIATCMEP5 WTPZ25 for 
more details.

Tropical Storm Greg is centered near 14.4N 132.1W, moving W at 
10 kt. Estimated minimum central pressure is 1003 mb. Maximum 
sustained winds are 40 kt with gusts to 50 kt. Scattered 
moderate to strong convection is within 90 nm of the center. 
Greg is forecast to gradually weaken during the next 24 to 48 
hours, becoming a remnant low by Thursday. See the latest NHC 
forecast/advisory under AWIPS/WMO headers MIATCMEP2 WTPZ22 for 
more details.


A tropical wave north of 06N along 90W is moving west at 10 to 
15 kt. Scattered moderate isolated strong convection is within 
60 nm W and 30 nm E of the wave axis from 06N to 09N.


The monsoon trough is analyzed E of the tropical cyclone 
activity from 09N85W to 11N100W. The ITCZ extends from 10N135W 
to beyond 08N140W. Scattered moderate and isolated strong 
convection is noted within 60 nm either side of the monsoon 
trough axis between 93W and 100w.



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 7 ft in a 
mix of long period north and southwesterly swell. Gentle 
southerly flow will generally prevail in the Gulf of California, 
except for moderate southerly flow over the northern Gulf. 

Moderate E to SE winds are expected across most of the area 
between just west of Tehuantepec and Acapulco through early Mon.
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 
Oaxaca, Guerrero, Michoacan, Colima and Jalisco through Tue, 
then pass south of the Revillagigedo Islands Wed as a major 


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. 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 an active zone of tropical 
cyclones between 12N and 20N will maintain fresh N to NE winds W 
of 125W through mid-week. Seas associated with T.S. Greg are 
already propagating across the waters N of 20N W of 130W. By 
Thursday night, cross equatorial southwesterly swell of 8 to 9 
ft will spread over the waters south of 10N and east of 110W, 
persisting into next weekend.