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Eastern North Pacific Tropical Weather Discussion

AXPZ20 KNHC 150349

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0405 UTC Wed Aug 15 2018

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 
0200 UTC. 


A well defined low pressure center near 10.9N 121.2W 1008 MB AT 
0300 UTC, has become better organized this evening, and the 
convective pattern currently supports an upgrading of this 
system to Tropical Depression Fourteen-E. The tropical 
depression is moving W at 12 kt, with maximum sustained winds to 
30 kt occurring within 60 nm across the northern quadrant. 
Scattered moderate to strong convection is observed in bands 
within 180 nm across the NW quadrant, while scattered moderate 
isolated strong convection is seen from 90 to 330 nm across the 
SW quadrant. The depression is expected to continue moving 
westward through Thu while gradually strengthening to tropical 
storm force, before reaching warmer waters and more favorable 
atmospheric conditions Thu night into the weekend, when it is 
expected to move more northwestward and strengthen to hurricane 
force. See latest NHC forecast/advisory under AWIPS/WMO headers 
MIATCPEP4/WTPZ34 KNHC for more details.


A tropical wave is entering the basin along 80W-81W, moving 
westward near 15 kt. Scattered moderate to strong convection is 
occurring both east and west of the wave along the monsoon 
trough, from 05N to 12N east of 87W and across coastal portions 
of Panama and Colombia.


The monsoon trough extends from 09N72.5W TO 10N97W to Tropical 
Depression FOURTEEN-E near 10.9N 121.2W. Scattered moderate to 
strong convection is noted E of 97W, and within 180 nm S of the 
trough between 102W and 113W.



Weak ridging persists across the waters west of Baja California, 
supporting gentle to moderate NW wind flow and 4 to 5 ft seas in 
the adjacent offshore waters. Little change in this wind pattern 
is expected for the next few days. Long period southerly swell 
will spread into the regional waters this afternoon through Fri 
to raise seas to 6-8 ft.

Gentle to moderate SE breezes continue across the Gulf of
California, although brief pulses of moderate to fresh W to SW
winds are possible over the far northern Gulf tonight into Wed, 
and again nightly through the week. The approaching southerly 
swell will move into the southern waters this afternoon through 
Fri to raise seas to 4-7 ft.

Farther south, cross equatorial S to SW swell will move into the 
offshore waters between Puerto Angel and Baja California Sur 
late tonight through Wed, with seas peaking at 7 to 10 ft Wed 
evening into Thu morning, and highest seas across the waters 
between Guatemala and Cabo Corrientes. This will produce very 
large and dangerous surf conditions along the coastlines and 
outer reefs with localized breaking waves 15-20 ft Wed through 
Thu morning. 

Looking ahead, fresh to briefly strong northerly gap winds are 
expected Thu night and Fri night across the Gulf of Tehuantepec.


Gulf of Papagayo: Fresh gaps winds are expected during the
overnight hours through mid week followed by fresh nocturnal 
easterly flow through Fri morning. 

Gentle to occasionally moderate E winds are forecast elsewhere N 
of the monsoon trough which will meander between 09N and 11N. 
Moderate to locally fresh southerly winds are forecast S of the 
monsoon trough through early next week. Long period S to SW 
swell has spread into the regional waters today and raised 
offshore seas to 6 to 8 ft on either side of the Galapagos 
Islands. A stronger and larger pulse of SW swell will move into 
the regional waters overnight through Wed. This next pulse of 
cross equatorial swell will raise seas to 7-10 ft Wed through 
early Thu before slowly subsiding through Fri, and produce large 
and dangerous surf conditions along the coasts and outer reefs.


Weak 1010 mb low pressure is centered near 17.5N133.5W, along a 
weakening tropical wave moving W-NW at 10 to 15 kt. Scattered 
moderate isolated strong convection has flared within 150 nm 
across the NW quadrant of the low. Fresh easterly winds are 
still occurring across the northern periphery of the low center, 
with seas 6 to 7 ft. Building high pressure north of the area 
will allow the area of fresh easterly winds to expand, and seas 
may build to around 8 ft, even as the low pressure opens into a 
trough over the next couple of days, reaching 140W by Wed night. 

Farther to the northwest, the remnant low of Kristy is centered 
near 25N140W, with an estimated pressure of 1014 mb. The low is 
weakening, and a recent scatterometer pass showed generally 
moderate winds north of the low pressure as it drifts west of 
the area. 

Long-period cross-equatorial southerly swell, in the form
of 7 to 10 ft seas, will propagate N across the tropical waters 
S of 20N E of 120W tonight through Thu, and then subside to less 
than 8 ft on Thu night.