000
AXPZ20 KNHC 171604
TWDEP 

TROPICAL WEATHER DISCUSSION                                  
NWS NATIONAL HURRICANE CENTER MIAMI FL                      
1605 UTC TUE MAY 17 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 1200 UTC surface analysis and satellite imagery through
1500 UTC.     
  
.INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...                

The monsoon trough is along 08N78W to 08N85W to 07N95W to
08N103W to 08N107W. The ITCZ continues from 08N107W to 09N120W
to 09N130W. Convective precipitation...Scattered strong from 07N
to 09N between 94W and 100W. A surface trough is along 14N130W
10N133W 05N135W. Convective precipitation...scattered moderate
to isolated strong within 360 nm to the east of the surface
trough from 11N to 14N...and within 180 nm to the west of the
trough from 11N to 12N. Convective precipitation...scattered
strong from 08N TO 09N between 135W and 136W...and from 06N to
07N between 137W and 138W.

Other convective precipitation...scattered strong from 02N to
06N from 86w eastward. The atmospheric conditions should remain
favorable for sustained precipitation in this area through
tonight. Low level moisture is forecast to diminish, and the
winds aloft will become less favorable for vertical lift
thereafter.

A surface trough is along 118W/120W from 11N to 14N. Convective
precipitation...scattered moderate to isolated strong within 90
nm to the east of the trough...and within 45 nm to the west of
the trough.

.DISCUSSION...                                             

A surface ridge extends from a 1029 mb subtropical high pressure
center that is near 36N139W...through 32N137W to 25N129W 22N118W
and 18N107W. The pressure gradient, that exists between the
ridge and the ITCZ/monsoon trough that is to the southwest, is
supporting mainly moderate to fresh trade winds. The wind speeds
are enhanced, to the northeast of a surface trough that is along
14N130W 10N133W 05N135W. The subtropical high will migrate
northwestward and merge with a new area of surface high
pressure, that is behind a cold front that is well to the north
of the area. The ridge will shift to the west and weaken,
shrinking the area of fresh trade winds westward. Fresh to
strong northeast winds should remain just west of the trough
until Wednesday afternoon. Scattered moderate convective
precipitation is around the surface trough. Precipitation that
has been closed to the trough has waned during the last day or
so. The available moisture is expected to diminish more during
the next few days, further limiting the chance of significant
deep convective precipitation. 

Northwesterly to northerly swell has built seas to 8 feet to the
north of 29N between 118W and 126W this morning/today. This
swell is originating in an area of 20 knot to 30 knot winds that
is just to the north of the forecast area off the California
coast. The winds and swell will shift westward as the
subtropical ridge shifts westward. Combined seas to 9 feet are
expected in the forecast waters that are to the north of 28N to
the west of 126W by the end of the forecast period early
Thursday morning.

$$ 
mt