Tropical Weather Discussion
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AXPZ20 KNHC 250236

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0235 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 0000 UTC surface analysis and satellite imagery through
0145 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 in the basin.

Hurricane Hilary is centered near 15.0N 105.7W at 25/0300 UTC,
moving WNW at 8 kt. Estimated minimum central pressure is 982
mb. Maximum sustained winds have increased to 85 kt with gusts
to 105 kt. Numerous moderate scattered strong convection are
within 150 nm in the N semicircle and 90 nm in the S semicircle.
A cluster of moderate convection is from 08N to 18N between 100W
and 104W. Continued strengthening is forecast during the next 24
hours, and Hilary is likely 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 15.2N 118.2W at 25/0300
UTC, moving WNW at 3 kt with a minimum central pressure of 993
mb. Maximum sustained winds have increased to 60 kt with gusts
to 75 kt. Clusters of moderate to strong convection are within
120 nm in the N semicircle and 90 nm in the S semicircle.
Scattered moderate convection was noted elsewhere from 13N to
18N between 116W and 120W. Irwin will remain in relatively close
proximity to Hilary the next several days. Gradual strengthening
is expected during the next 48 hours, and Irwin is forecast to
become a minimal hurricane later tonight or Tue. See the latest
NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5 WTPZ25
for more details.

Tropical Storm Greg is centered near 14.8N 134.9W AT 25/0300
UTC, moving WNW at 8 kt. Estimated minimum central pressure is
1003 mb. Maximum sustained winds remain 40 kt with gusts to 50
kt. Clusters of moderate to strong convection are within 120 nm
in the N and 60 nm in the S semicircles of the center. Greg is
expected to remain a minimal tropical storm through the next 24
hours or so, before weakening ensues. Greg could become a
tropical depression by Wed, and a remnant low by Thu. See the
latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2
WTPZ22 for more details.


A tropical wave is just to the W of the Gulf of Tehuantepec
along 98W north of 08N moving west at 10 to 15 kt. No deep
convection is currently noted.


The monsoon trough is analyzed E of the tropical cyclone
activity from 09N79W to 09N90W to 12N99W. The ITCZ extends from
12N136W to beyond 10N140W. Scattered moderate convection was
from 05N to 11N east of 97W and within 90 nm of the ITCZ axis.



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 through
Wednesday. Gentle southerly flow will generally prevail in the
Gulf of California, except for moderate southerly flow over the
northern Gulf. Large 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 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.

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