000
AXPZ20 KNHC 290927
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE NOV 29 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.

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

MONSOON TROUGH 09N84W TO 06N100W TO 10N120W. ITCZ FROM 10N120W 
TO 1011 MB LOW PRES NEAR 10N128W TO BEYOND 09N140W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION FROM 11N TO 14N BETWEEN 
107W AND 110W. ISOLATED MODERATE CONVECTION FROM 11N TO 15N 
BETWEEN 110W AND 114W. A DIFFLUENT PATTERN ALOFT IS HELPING TO 
INDUCE THIS CONVECTIVE ACTIVITY.

...DISCUSSION...

A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE AREA BETWEEN MEXICO 
AND 145W. A DEEP UPPER LEVEL TROUGH EXTENDS FROM NE MEXICO 
ACROSS SOUTHERN BAJA CALIFORNIA TO A CUT-OFF LOW NEAR 16N116W. 
ANOTHER CUT-OFF LOW IS OVER THE FAR NW CORNER OF THE AREA. IN 
BETWEEN...THERE IS AN UPPER RIDGE ROUGHLY EXTENDING FROM 08N138W 
TO BEYOND 32N122W. AN UPPER ANTICYCLONE IS CENTERED OVER THE 
PACIFIC COAST OF COSTA RICA AND EXTENDS A RIDGE ACROSS SE MEXICO 
AND NORTHERN CENTRAL AMERICA WHERE STRONG UPPER LEVEL SUBSIDENCE 
AND IMPLIED DRY AIR MASS IS NOTED. THE FIRST CUT-OFF LOW WILL 
PERSIST FOR ANOTHER 24 HOURS BUT IS EJECTED NE WED AS THE UPPER 
WINDS BECOME MORE ZONAL ACROSS THE REGION. THE SECOND WILL 
MEANDER OVER THE NW PORTION OF THE FORECAST REGION AND GRADUALLY 
DISSIPATE THROUGH THU. A STRONG ANTICYCLONE WILL PERSIST NEAR 
COSTA RICA AND NICARAGUA. THIS PATTERN WILL FAVOR STRONG SW 
UPPER LEVEL WINDS BETWEEN 100W AND 115W WHICH WILL TRANSPORT 
ITCZ MOISTURE ACROSS MEXICO.

PRES GRADIENT BETWEEN A STRONG HIGH PRES CENTERED N OF THE 
DISCUSSION AREA AND A TROUGH LOCATED ALONG 144W/145W IS 
PRODUCING AN AREA OF FRESH NE TO E WINDS PARTICULARLY N OF 17N W 
OF 135W...WITH SEAS OF 11 TO 13 FT IN MIXED E AND NW SWELL. 
SCATTEROMETER DATA CONFIRMED THESE WIND SPEEDS. AS HIGH PRES 
FURTHER STRENGTHENS N OF THE AREA LATE TODAY INTO WED...EXPECT 
INCREASING WINDS OF 20 KT AND BUILDING SEAS OF 9-11 FT ACROSS 
THE N WATERS PARTICULARLY N OF 25N AND W OF 116W.  

AN EARLIER ASCAT PASS INDICATED THAT WINDS HAVE DIMINISHED TO 
10-15 ACROSS THE GULF OF CALIFORNIA. A COLD FRONT WILL BRING 
ANOTHER ROUND OF FRESH NLY WINDS ACROSS THE N PORTION OF THIS 
GULF BY THU. 

STRONG N WINDS SURGING THROUGH THE CHIVELA PASS INTO THE GULF OF 
TEHUANTEPEC ARE PRODUCING GALE FORCE WINDS AT 25-35 KT BASED ON 
THE 0404 UTC ASCAT PASS. A JASON PASS ALSO CROSSED THE REGION 
AND INDICATED SEAS OF UP TO 15 FT. WINDS ARE FORECAST TO 
DIMINISH BELOW GALE FORCE IN ABOUT 24 HOURS. HOWEVER...NLY WINDS 
OF 30 KT ARE EXPECTED TO PERSIST THROUGH WED NIGHT...WITH SEAS 
SLOWLY SUBSIDING FROM 10-15 FT TODAY TO 8-10 FT WED.

A SURGE OF NLY WINDS IN THE W CARIBBEAN WILL INCREASE WINDS TO 
20 KT ACROSS THE GULF OF PAPAGAYO. WINDS ARE FORECAST TO PEAK  
IN THE MORNING...AIDED BY NOCTURNAL DRAINAGE FLOW.

$$
GR