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Eastern North Pacific Tropical Weather Discussion



165 
AXPZ20 KNHC 150940
TWDEP 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1005 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 0600 UTC surface analysis and satellite imagery through 
0830 UTC. 

...SPECIAL FEATURE...

Tropical Depression Fourteen-E is centered near 10.8N 122.3W at 
0900 UTC, moving W at 12 kt. Estimated minimum central pressure 
is 1007mb. Maximum sustained winds area 30 kt with gusts to 40 
kt. The surface circulation of the tropical depression is very 
small with maximum winds occurring within 60 nm across the 
northern quadrant. However, satellite imagery depicts a modest 
sized middle level circulation a bit to the west of the surface 
low, where scattered moderate to strong convection is observed 
in bands within 240 nm and 90 nm across the SE quadrants, while 
scattered moderate isolated strong convection is seen from 180 
to 360 nm across the SW quadrant. The depression is expected to 
continue moving westward through Thu while gradually 
strengthening, reaching hurricane strength Thu night as it 
reaches warmer waters and more favorable atmospheric conditions. 
See latest NHC forecast/advisory under AWIPS/WMO headers 
MIATCPEP4/WTPZ34 KNHC for more details.

...TROPICAL WAVES...

A weak tropical wave is moving across the Gulf of Tehuantepec 
region and SW portions of the Gulf of Mexico and southern Mexico 
tonight. Widely scattered moderate to strong convection is 
occurring within about 300 nm on either side of the wave across 
the Pacific waters. The majority of the moisture and energy 
associated with this wave will shift WNW across Mexico and the 
SW Gulf of Mexico during the next 24 hours. 

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

The monsoon trough extends from 09.5N73.5W TO 10N97W TO 
08.5N110W to Tropical Depression FOURTEEN-E near 10.8N122.3W. 
Widely scattered to scattered moderate to strong convection is 
noted within 240 nm either side of the trough E of 103W, and 
within 90 nm N and 150 nm S of the trough between 106W and 116W.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 

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. The remnants of former tropical 
cyclone John, in the form of a low level cloud swirl, have 
shifted SE into the waters about 150 nm offshore of Punta 
Eugenia, and are acting the weaken the local pressure gradient, 
and the winds. This weak trough at the surface is forecast to 
dissipate by Fri. Little change in this wind pattern is expected 
through Fri, before the trough dissipates and allows the pres 
gradient to tighten modestly leading to freshening NW winds. 
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 possible over the far northern Gulf tonight into Wed, and 
again nightly throughout 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, strong 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 Manzanillo. This will produce 
very large and dangerous surf conditions along the coastlines 
and outer reefs with localized breaking waves building to 15-20 
ft today through Thu morning. 

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

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

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 Mon 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 and will raise seas to 
7-10 ft by midday through early Thu before slowly subsiding 
through Fri. This swell will produce large and dangerous surf 
conditions along the coasts and outer reefs of the region.

REMAINDER OF THE AREA...   

Weak 1011 mb low pressure is centered near 17N134.5W, along a 
weakening tropical wave moving W-NW at 10 to 15 kt. Scattered 
moderate isolated strong convection has flared overnight from 
within 60 to 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 7 to 9 ft. Building high pressure 
north of the area will maintain this area of fresh easterly 
winds through Wed , even as the low pressure opens into a trough 
over the next couple of days, and reached 140W Wed night. 

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. 

$$
Stripling