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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 230945
TWDEP 

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

...SPECIAL FEATURES... 

Tropical Storm Greg is centered near 14.7N 127.7W, moving W at 
12 kt. Estimated minimum central pressure is 1001 mb. Maximum 
sustained winds are 45 kt with gusts to 55 kt. Scattered 
moderate to strong convection is noted within 90 nm SW of the 
center, with scattered moderate isolated strong convection 
elsewhere within 120 nm. Little change in intensity is forecast 
through the next 24 hours, with slow weakening expected 
thereafter as Greg tracks over cooler waters and a more stable 
atmosphere. Greg may weaken to a tropical depression by late 
Tue. See the latest NHC forecast/advisory under AWIPS/WMO 
headers MIATCMEP2 WTPZ22 for more details.

Tropical Storm Hilary centered near 12.5N 101.6W, or about 280 
nm S of Acapulco Mexico, is moving WNW at 13 kt. Estimated 
minimum central pressure is 1005 mb. Maximum sustained winds are 
35 kt with gusts to 45 kt. Scattered moderate to strong 
convection is observed in bands within 120 nm NE and 60 nm SW of 
the center. Conditions are favorable for significant 
strengthening during the next 24 to 48 hours, and it is possible 
Hilary could intensify to a hurricane by late Mon as it 
continues on a WNW track. See the latest NHC forecast/advisory 
under AWIPS/WMO headers MIATCMEP4 WTPZ24 for more details.

Newly formed Tropical Storm Irwin is centered near 14.7N 115.2W, 
moving WNW at 8 kt with minimum central pressure of 1005 mb. 
Maximum sustained winds are 35 kt with gusts to 45 kt. Scattered 
moderate to strong convection is within 150 nm of the southern 
semicircle. This system is encountering strong northerly shear, 
but is expected to intensify once the vertical shear diminishes. 
It will remain in relatively close proximity to Hilary the next 
few days, and some interaction between the two tropical cyclones 
may occur later this week. See the latest NHC forecast/advisory 
under AWIPS/WMO headers MIATCMEP5 WTPZ25 for more details.

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

A monsoon trough is analyzed E of the tropical cyclone activity 
from 10N85W to 12N97W. The ITCZ extends from 11N129W to 07N140W. 
Scattered moderate isolated strong convection is noted from 07N 
to 10N between 93W and 102W. 

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gentle to moderate NW winds off the Baja California peninsula 
are expected to continue through Monday, 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 winds are expected across most of the area between 
Tehuantepec and Acapulco today, becoming SE 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 Oaxaca and Chiapas through tonight, then the 
offshore waters of Michoacan, Guerrero and Jalisco through Tue. 

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.

$$
Mundell