000
AXPZ20 KNHC 052136
TWDEP

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
2038 UTC Wed Jul 5 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
2130 UTC.

...SPECIAL FEATURE...

A surface low is analyzed near 18N118W, moving in tandem with a 
tropical wave along 118W that extends from 11N to 21N. Most recent
visible satellite imagery shows a well defined exposed low level
center becoming increasingly displaced from the deep convection 
associated with the wave. An 1806 UTC ASCAT pass showed NE to E 
winds of 20-25 KT within 180 NM in the north semicircle of the 
low but did not capture the area of S to SW monsoonal flow to the
southeast of the low. Scattered moderate isolated strong 
convection is noted within 120 nm W of the wave axis from 15N to 
17N. This low is beginning to move into less favorable 
environmental conditions, and the chances of this system becoming
a tropical depression are decreasing. Please refer to the NHC 
Tropical Weather Outlook at hurricanes.gov for more information.

...TROPICAL WAVES...

In addition to the wave mentioned above along 118W, a tropical 
wave is analyzed from 06N105W to 15N108W. Scattered moderate 
convection is noted within 180 nm either side of the wave axis 
from 07N to 14N. NWP model guidance suggests that a surface low 
may develop along this wave near 10N/11N in 24 hours or so. A 
low pressure has been introduced into the High Seas forecast in 
24 hours with an area of monsoonal S to SW winds of 20 to 25 kt 
forecast near the low by 48 hours. Long term environmental 
conditions appear to be favorable for further strengthening of 
this low. Please refer to the NHC Tropical Weather Outlook at 
hurricanes.gov for more information.

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

The monsoon trough extends across Panama and Costa Rica into the
east Pacific near 11N95W to 11N110W, then resumes from a low 
near 18N118W to 11N127W to 10N140W. Scattered moderate isolated 
strong convection was noted within 180 to 240 NM either side of
the axis between 92W and 103W extending to the Gulf of
Tehuantepec, and within 180 NM south of the monsoon trough
between 125W and 140W.  

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

A weak ridge of high pressure extends across the waters west of 
Baja California. Light to moderate anticyclonic flow prevails 
west of the Baja California peninsula, moderate to fresh N winds 
in the Gulf of Tehuantepec, and light to gentle winds over the 
Gulf of California. Seas are 4-6 ft in the open waters west of 
Mexico, with 1-2 ft seas in the Gulf of California. Nocturnal 
winds will pulse to near 25 kt each night in the Gulf of 
Tehuantepec, and diminish during the day. Little change is 
expected elsewhere.
    
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND 
WITHIN 750 NM OF ECUADOR... 

Moderate to locally fresh nocturnal winds are expected in the 
Gulf of Papagayo this week. Gentle to moderate southerly winds 
are expected south of the monsoon trough this week. Long period 
cross-equatorial S to SW swell will build seas west of Colombia 
and Ecuador Wednesday night and Thursday, then subside Friday.

REMAINDER OF THE AREA...
  
See special feature section for more information on the low 
centered near 18N118W. Outside the monsoonal influence of this 
area, gentle to moderate trade winds will prevail north of the 
monsoon trough, while moderate to fresh southerly winds will
develop south of the trough axis. Seas will be generally 5-7 ft.
These general conditions will prevail through the rest of the 
week. Long period cross-equatorial S to SW swell will build seas 
to 8 to 9 ft south of 04N and east of 120W by Thursday and shrink
in area by Friday. 

$$
Cobb