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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 232026
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1925 UTC Sun Jul 23 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 1800 UTC surface analysis and satellite imagery through
2100 UTC.

...SPECIAL FEATURES... 

The Eastern Pacific region remains very active with three
tropical cyclones: from west to east, Greg, Irwin and Hilary. 
Irwin and Hilary are forecast to become hurricanes. So far in 
July, five named storms have developed.

Tropical Storm Greg is centered near 14.4N 130.1W at 23/2100 
UTC, moving W at 12 kt. Estimated minimum central pressure is 
1001 mb. Maximum sustained winds are 45 kt with gusts to 55 kt. 
Numerous moderate isolated strong convection is noted within 120 
nm east semicircle of the center. Greg is forecast to maintain 
its intensity for another 24 hours, followed by gradual weakening
due to the dry air, increasing shear, and cooler sea surface 
temperatures after 48 hours. Greg is expected to weaken to a 
tropical depression on Wednesday and to a remnant low on 
Thursday. See the latest NHC forecast/advisory under AWIPS/WMO 
headers MIATCMEP2 WTPZ22 for more details.

Tropical Storm Irwin is centered near 14.0N 116.6W at 23/2100 
UTC, moving W at 7 kt with minimum central pressure of 1003 mb. 
Maximum sustained winds are 40 kt with gusts to 50 kt. Scattered
moderate isolated strong convection is from 12.5N to 15.5N 
between 113W and 118W. 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 on Tuesday. See the latest NHC 
forecast/advisory under AWIPS/WMO headers MIATCMEP5 WTPZ25 for 
more details.

Tropical Storm Hilary is centered near 12.7N 102.3W at 23/2100 
UTC, moving WNW at 9 kt. Estimated minimum central pressure is 
1003 mb. Maximum sustained winds are 40 kt with gusts to 50 kt. 
Numerous moderate scattered strong convection is in a band within
180 nm NE semicircle of center. Scattered moderate isolated 
strong is within 120 nm SW semicircle. Conditions are favorable 
for significant strengthening during the next 24 to 48 hours, and
it is possible Hilary could intensify to a hurricane on Mon as 
it continues on a WNW track. See the latest NHC forecast/advisory
under AWIPS/WMO headers MIATCMEP4 WTPZ24 for more details.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

The monsoon trough is analyzed E of the tropical cyclone activity
from 09N84W to 11N98W. The ITCZ extends from 11N132W to beyond 
07N140W. Scattered moderate isolated strong convection is noted 
from 05N to 10N E of 88W. A cluster of moderate to isolated 
strong convection is from 11N to 13.5W between 96W and 99W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gentle to moderate NW winds off the Baja California peninsula 
are expected to continue through mid week, as high pressure 
remains centered NW of the area and shifts NW. 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 Tehuantepec and Acapulco through early Mon. The forecast
track and intensity of T.S. Hilary is expected to impact the 
offshore waters within 250 nm of the coast of the Mexican States 
of Chiapas and Oaxaca through tonight, then the offshore waters 
of Guerrero, Michoacan and Jalisco through Tue. Hilary is
forecast to pass south of the Revillagigedo Islands on Wednesday.

OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR...

Across the Gulf of Papagayo, moderate to fresh offshore winds 
will pulse to fresh each night with 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 southerly winds are expected south of the 
monsoon trough axis E of 95W. Long period cross-equatorial SW 
swell creating 5-7 ft seas will continue to propagate into the 
waters reaching the coast of Central America through the weekend.
Another pulse of large southerly swell will move into the region
Mon and Tue.

REMAINDER OF THE AREA... 

T.S. Greg will gradually dissipate through Tue. The pressure 
gradient between high pressure north of the area and an active 
zone of tropical systems between 12N and 20N will maintain fresh 
trade winds and 6-7 ft seas north of 20N the next several days. 
Northerly swell in the form of 7-8 ft seas will propagate S of 
32N between 125W and 135W the next two days.

$$
GR