000
AXPZ20 KNHC 041013
TWDEP 

Tropical Weather Discussion                                 
NWS National Hurricane Center Miami FL                      
1005 UTC SAT JUN 04 2016

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
0800 UTC.

...SPECIAL FEATURE...

A broad and elongated area of low pressure is analyzed along the
monsoon trough near 09.5N118.5W with an estimated pressure of
1007 mb. Satellite imagery overnight showed a well defined
middle level circulation just to the west of the low level
center, where convection had increased in recent hours. Widely
scattered to scattered moderate to strong convection developed a
band occurring within 210 nm across the west semicircle of the
assumed center. Satellite and microwave imagery continue to
suggest that this system remains elongated northeast to
southwest. Moderate east to southeast wind shear also continues
to impact this low. the combination of these factors indicates
that this system has not yet gained sufficient organization to
be classified as a tropical cyclone. However, atmospheric
conditions remain favorable for gradual development, and there
is a medium chance of tropical cyclone development over the next
couple of days. Please refer to the Tropical Weather Outlook
under AWIPS/WMO headers TWOEP/ABPZ20 for more details. 

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

The monsoon trough extends from 12.5N98W to 14N104W to low pres
1007 mb near 09.5N118.5W to 07N125W, where it transitions to the
ITCZ, continuing on to beyond 08.5N140W. Scattered to locally
numerous moderate to strong convection is noted from 07N to 14N
between 94W and 112W. Widely scattered to scattered moderate to
strong convection is noted within 210 nm across the west
semicircle of low pres near 09.5N118.5W. Scattered strong
convection is noted within 60 nm of the ITCZ between 125W and
133W. Isolated to widely scattered moderate to strong convection
is occurring within 60 nm of the coast of Central America from
86W to 101W.
  
...DISCUSSION...   

North of 15N, east of 120W:

A weak surface ridge extends from a 1018 mb surface high
centered near 22N122W southeastward to just south of the
Revillagigedo Islands near 18N110W. This ridge is maintaining a
light to gentle northwest to west breeze across the area east
and southeast of the ridge, where wave heights are generally 4
to 6 ft in mixed southwest and northwest swell. The pressure
gradient across the offshore waters of the Baja California
Peninsula is sufficient to produce northwesterly winds in the 15
kt range early this morning, but evening seabreezes across
central portions enhanced winds to around 20 kt with gusts to 25
kt through midnight. Little change in this overall scenario is
expected over the next couple of days. Looking ahead, a surface
trough along the Gulf of California and northwest Mexico through
early next week will deepen, allowing northerly flow off the
central coast of the Baja California peninsula and across the
northern Gulf of California to increase to near 20 kt, with
afternoon seabreezes increasing isolated areas to near 20-25 kt.
Seas will build to 5 to 7 ft accordingly. Showers and
thunderstorms will increase early next week along the coasts of
Guerrero and Oaxaca as a broad low pressure area forms over
Central America. 

South of 15N, east of 120W:

Moderate southwest flow converging into the monsoon trough is
enhancing areas of showers and thunderstorms along and south of
the trough early this morning between 94 and 112W. This pattern
will continue through the next couple of days, with winds
expected to increase to near 20 kt by Sunday and seas building
to 6-8 ft. This southwest flow will increase in response to the
development of broad low pressure that has already become to
form across Central America and the Yucatan Peninsula. This
broad cyclonic gyre will shift slowly northwest across the
Yucatan and southern Gulf of Mexico Sunday through Monday and
draw abundant tropical moisture across Central America from
Nicaragua to far southeastern Mexico. This scenario will produce
a high chance of heavy rainfall across this area beginning today
into early next week. Offshore seas will build to 8 to 9 ft in
this area as well as the southwest flow freshens. 
    
Elsewhere from the equator to 32N east of 140W:
   
A weak subtropical ridge north of 25N is allowing only light to
moderate northeast trade winds flow farther south into the
tropics, generally south of 18N. There is enough convergence in
the lower levels of the atmosphere to support scattered
moderate to strong convection along the ITCZ between 125W and
133W. The ridge will build over the next couple of days north of
20N, just as the low pressure area currently near 09.5N118.5W
migrates west-northwest and south of the ridge between 10N and
15N. Looking ahead, a weak frontal boundary will cross east of
140W and north of 25N early next week and stall, but with little
impact on winds or seas.
 
$$
Stripling