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Eastern North Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 201004
TWDEP 

Tropical Weather Discussion 
NWS National Hurricane Center Miami FL 
1005 UTC WED SEP 20 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 0600 UTC surface analysis and satellite imagery through 
0900 UTC.

...SPECIAL FEATURES...

The Post-Tropical remnant low pressure center of NORMA has a 
pressure of 1008 mb, and it is near 22N116W. Precipitation: a 
swirl of multilayered clouds and possible rainshowers covers the 
area that is from 16N to 25N between 114W and 121W. This feature 
will continue to move slowly NW for the next few days.
Associated winds and seas will wind down slowly before the low 
center dissipates on Thursday.

The Post-Tropical remnant low pressure center of OTIS has a 
pressure of 1012 mb, and it is near 18N130W. Precipitation: a 
swirl of multilayered clouds and possible rainshowers covers the 
area that is from 16N to 25N between 114W and 121W. A sufficient 
pressure gradient exists between this low center and a surface 
ridge to the NW in order to create strong NE to E winds 20 to 25 
kt WITHIN 90 NM in the NW QUADRANT. The sea heights range from 8 
to 9 feet. The low center will continue to move WSW during the 
next 2 days and dissipate gradually. An area of fresh to strong 
NE to E winds, and seas from 8 to 9 feet, will accompany the low 
center through Thursday.

...TROPICAL WAVES...

A tropical wave is along 95W/96W S OF 18N. Precipitation: 
scattered moderate to strong from 14N to 17N between 96W and 
101W. Global models suggest that it is possible that a low 
pressure center may develop in this region in a few days as 
active convective precipitation continues.

..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...         

MONSOON TROUGH FROM 09N78W TO 10N86W TO 14N96W TO 12N109W TO 
12N115W TO 11N124W TO 14N134W TO 13N140W. SCATTERED MODERATE 
ISOLATED STRONG WITHIN 390 NM S OF TROUGH E OF 90W, WITHIN 90 NM 
N OF TROUGH BETWEEN 86W AND TROPICAL WAVE, WITHIN 210 NM S OF 
TROUGH BETWEEN TROPICAL WAVE AND 95W, AND WITHIN 240 NM S OF 
TROUGH BETWEEN 100W AND 110W.

...DISCUSSION...   

OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  

A surface ridge passes through 34N136W to 25N122W.
Anticyclonic wind flow covers the area N through NW of the 
remnant lows of Norma and Otis. A surface trough is in the 
northernmost part of the Gulf of California, where fresh 
northerly winds prevail across the nearshore waters of Baja 
California Norte. The surface pressure gradient that exists 
between the ridge and the trough is supporting gentle to 
moderate N to NE winds, and seas in the range from 5 feet to 7 
feet. The ridge will build during the middle of the week as the 
remnants of Norma dissipate, which will freshen winds off the 
Baja California coast with seas building to 6 to 8 feet.

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

A tropical wave across the W Caribbean is moving slowly into the 
far eastern waters of the Pacific Ocean. Light to gentle 
monsoonal flow prevails to the south of the monsoon trough, 
while gentle to moderate southeasterly winds prevail to the N of 
the monsoon trough between 90W and the Gulf of Tehuantepec. 
Light to gentle northeasterly winds will develop briefly to the 
N of the monsoon trough Tue night before the trough lifts N and 
along the coasts. S to SW swell continues to propagate across 
the area with seas in the 6 to 8 foot range from 100W westward, 
and in the 4 to 6 foot range from 100W eastward.

REMAINDER OF THE AREA...

A 1030 mb high pressure center is located near 39N149W and 
extends S and SE into the waters N of 25N. The surface pressure 
gradient that exists between this high pressure, and the lower 
pressure that is in the vicinity of the monsoon trough, will 
maintain moderate to fresh trade winds to the N of 20N west of 
120W, and to the NW of Otis remnants, with seas in the 6 to 9 
foot range. The ridge will prevail in the northern waters during 
the next few of days with these general conditions persisting. 

$$
mt