000
AXPZ20 KNHC 100936
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT SEP 10 2011

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.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE FAR SW CARIBBEAN ACROSS 
COSTA RICA AND ENTERS THE EPAC NEAR 9.5N84W TO 12.5N92W WHERE IT 
HAS FRACTURED FROM THE REMAINDER OF THE TROUGH...THEN RESUMES 
AGAIN FROM 18N104W TO 20N110W TO LOW PRES 16N117W TO LOW PRES 
13.5N131W TO BEYOND 10N1410W. SCATTERED MODERATE CONVECTION WAS 
NOTED WITHIN 120 NM N OF AXIS BETWEEN 85W AND 89W.

...DISCUSSION...

LITTLE CHANGE HAS OCCURRED AT THE SURFACE DURING THE PAST 24 
HOURS...WITH A WEAK HIGH PRES RIDGE ACROSS W AND NW PORTIONS 
EXTENDING FROM A 1026 MB HIGH NEAR 37N140W TO NEAR 23N124W. A 
WEAK PRESSURE GRADIENT CONTINUES ACROSS THE AREA WITH TRADES 
LESS THAN 20 KT ACROSS THE AREA. DEEPENING SURFACE LOW PRESSURE 
ACROSS SRN CALIFORNIA AND SW ARIZONA IS INDUCING SLY WINDS TO 20 
KT ACROSS THE N PORTION OF THE GULF OF CALIFORNIA...WHICH IS 
EXPECTED TO PERSIST THROUGH SUNDAY NIGHT BEFORE DIMINISHING. 

TWO LOW PRESSURE SYSTEMS CONTINUE TO SPIN WITHIN THE MONSOON 
TROUGH. ONE IS CENTERED NEAR 16N118W 1008 MB WITH FRESH TO 
STRONG WINDS WITHIN 150 NM SW QUADRANT AND SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION NOTED WITHIN 270 NM W QUADRANT. THE 
SECOND LOW IS CENTERED NEAR 12.5N130W 1009 MB WITH FRESH TO 
STRONG WINDS WITHIN 210 NM NW AND 150 NM SE SEMICIRCLES AND 
SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 120 NM SW 
QUADRANT. THESE LOW PRESSURE CENTERS WILL REMAIN NEARLY 
STATIONARY AS THEY REMAIN EMBEDDED IN THE MONSOON TROUGH THROUGH 
THE FORECAST PERIOD. 

GAP WINDS...TROPICAL STORM NATE CONTINUES TO MEANDER SLOWLY 
ACROSS THE BAY OF CAMPECHE RESULTING IN NORTHERLY WINDS AT 20 KT 
TO FUNNEL THROUGH THE CHIVELA PASS AND INTO THE GULF OF 
TEHUANTEPEC REGION. WITH NATE CONTINUING ITS SLOW WESTWARD 
MOTION...THESE WINDS WILL DIMINISH BELOW 20 KT OVER THE GULF OF 
TEHUANTEPEC THIS EVENING. 

OTHERWISE...MARINE CONDITIONS ACROSS THE AREA ARE DOMINATED BY 
MIXED SE AND SW CROSS EQUATORIAL SWELL. THIS SWELL WILL CONTINUE 
TO PROPAGATE NORTHWARD THROUGH THE TROPICAL WATERS THROUGH THE 
FORECAST PERIOD.

$$
AL