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Eastern North Pacific Tropical Weather Discussion



310 
AXPZ20 KNHC 151558
TWDEP 

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL
1605 UTC Sun Jul 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 1200 UTC surface analysis and satellite imagery through 
1500 UTC.  

...SPECIAL FEATURE...

A weak 1007 mb surface low is centered near 13N132W. The 
overnight ASCAT scatterometer pass missed the system, but it is 
likely that peak sustained winds are near strong breeze 
conditions north of the center.  These winds should continue 
even with little development of the low, due to the moderate 
pressure gradient south of the surface ridge.  The system's 
center should reach our western border at 140W by Mon morning 
and associated strong wind out of our area by late Mon.  This 
system does have a moderate - 40 percent - chance of becoming a 
tropical cyclone within the next 48 hours. Refer to the EPAC 
Tropical Weather Outlook under AWIPS/WMO headers MIATWOEP/ABPZ20 
KNHC for additional information. 

...TROPICAL WAVES...

A tropical wave has moved into eastern Pacific and over Central 
America extending from 06N to 17N near 83W.  Scattered moderate 
convection is occurring over Nicaragua.

A tropical wave is analyzed from 05N to 13N near 97W and is 
estimated to be moving W at 15 kt.  No significant deep 
convection is associated with the system at this time.

A tropical wave is analyzed from 05N to 15N near 107W and is 
estimated to be moving W at 10-15 kt.  A 1011 mb low pressure 
center is analyzed to be along the wave's axis near 12N107W. 
Scattered moderate and isolated strong convection is occurring 
from 09N to 15N between 106W and 113W.  

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

The monsoon trough axis extends W from a 1008 mb low near 10N75W 
over the coast of Colombia, across Panama and Costa Rica, and to 
a 1011 mb low at 11N107W.  The ITCZ axis extends from 11N107W to 
08N127W.  The ITCZ begins again at 10N138W and extends W beyond 
140W.  Scattered moderate and isolated strong convection is 
observed from 03N to 07N between 77W and 81W.  Isolated moderate 
convection is occurring from 05N to 11N between 90W and 103W as 
well as within 120 nm of the ITCZ between 117W and 127W. 
Scattered moderate and isolated strong convection exists within 
180 nm N of the ITCZ between 138W and 140w.

...DISCUSSION...

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...

Gulf of Tehuantepec:  Strong pulses of northerly gap wind flow 
is expected during late night and morning hours through Wed. 
Seas will peak at 8 to 9 ft.  Conditions will subside on Thu and 
Fri. 

A surface ridge will meander across the area from near 23N116W 
to near 15N100W this week. A moderate NW breeze will develop 
within 90 nm of the Baja Peninsula during the evenings, 
otherwise gentle anticyclonic northerly winds are expected 
around the ridge axis, with 3 to 5 ft seas.   

Gulf of California: Moderate southerly flow will continue along 
30N through early Mon morning. Elsewhere, light to gentle 
southerly flow expected for the next 48 hours.  

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

Gulf of Papagayo: 

Gentle to occasionally moderate E winds are forecast elsewhere N 
of the monsoon trough which is meandering between 07N and 10N. 
Moderate southerly winds are forecast S of the monsoon trough 
for the next several days accompanied by 4 to 6 ft seas.

Extended model guidance is suggesting that long period southerly 
swell, in the form of 7 to 8 ft seas, will arrive along 03.4S to 
the E of 93W early Thu, and propagate N reaching the far 
offshore waters along 10N and W of 93W next weekend.   

REMAINDER OF THE AREA...

Refer to Special Features section above for information on a 
weak surface low near 13N132W.  

A surface ridge will meander across the discussion area from 
32N140W to 23N116W this week, with moderate to locally fresh 
anticylonic flow forecast elsewhere around the ridge accompanied 
by 4 to 7 ft seas. 

$$
Landsea/Nelson