000
AXPZ20 KNHC 122140
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT NOV 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

MONSOON TROUGH FROM 09N84W TO 07N94W. ITCZ AXIS FROM 07N94W TO 
10N122W WHERE IT IS DISRUPTED BY A TROUGH FROM 13N125W TO 
07N130W. THERE IS SCATTERED MODERATE CONVECTION NOTED S OF 110W 
WITHIN 120 NM E OF TROUGH. THE ITCZ THEN RESUMES FROM 08N132W TO 
09N140W. NO SIGNIFICANT CONVECTION WAS NOTED WITH THE ITCZ OR 
MONSOON TROUGH.

...DISCUSSION...

STRONG HIGH PRESSURE 1034 MB CENTERED NEAR 37N152W HAS RIDGE 
EXTENDING SE TO NEAR 19N128W. LOW PRESSURE 1005 MB IS CENTERED 
NEAR 30N122W. LATEST ASCAT PASS INDICATES GALE FORCE WINDS OVER 
THE SW QUADRANT OF THIS LOW DUE TO A RELATIVELY TIGHT PRESSURE 
GRADIENT BETWEEN THIS LOW AND THE AFOREMENTIONED RIDGE...AND A 
GALE WARNING WAS ISSUED FOR THIS AREA. THIS IS A GREAT EXAMPLE 
OF THE BENEFIT OF SCATTEROMETER WINDS...AS WITHOUT THIS WELL 
PLACED ASCAT PASS EVIDENCE OF THE GALE FORCE WINDS WOULD HAVE 
FALLEN BETWEEN THE SPARSE OCEANIC OBSERVATIONS. WINDS ARE 
EXPECTED TO DIMINISH BELOW GALE FORCE WITHIN 24 HOURS AS THE LOW 
PRESSURE CENTER FILLS. 

THERE IS ALSO A TIGHT PRESSURE GRADIENT BETWEEN THE LOW PRESSURE 
MENTIONED ABOVE AND HIGH PRESSURE OVER THE GREAT BASIN REGION OF 
THE UNITED STATES. THIS GRADIENT IS MAINTAINING FRESH 20 KT SW 
WINDS OVER THE FAR N PART OF THE GULF OF CALIFORNIA. THESE WINDS 
ARE EXPECTED TO DIMINISH BELOW 20 KT BY SUN MORNING AS THE LOW 
FILLS.  

NW SWELLS WITH COMBINED SEAS TO 18 FT PREVAIL OVER THE ENTIRE NW 
PART OF THE AREA. THE NW SWELL WILL SPREAD SE AND ENCOMPASS MUCH 
OF THE AREA W OF 11OW OVER THE NEXT 48 HOURS...ALTHOUGH OVERALL 
SEA HEIGHTS WILL SUBSIDE TO NO MORE THAN 10 FT AS THE SWELL 
DECAYS. 

GULF OF TEHUANTEPEC...RECENT ASCAT PASS INDICATED 20 KT WINDS 
REMAIN OVER A SMALL AREA N OF 14N BETWEEN 94W AND 96W. THESE 
WINDS WILL DIMINISH BELOW 20 KT TONIGHT. SE SWELL GENERATED FROM 
THE TEHUANTEPEC EVENT CONTINUE TO PROPAGATE SW...AND COMBINED 
SEAS GREATER THAN 8 FT ARE REACHING AS FAR E AS 108W. THE NE 
SWELL WILL CONTINUE TO SUBSIDE...AND COMBINED SEAS WILL FALL 
BELOW 8 FT BY MON. 

GULF OF PAPAGAYO...ENHANCED GRADIENT FLOW OVER THE SW CARIBBEAN 
ALONG WITH OVERNIGHT DRAINAGE EFFECTS OFF THE HIGH TERRAIN OF 
NORTHERN COSTA RICA MAY ALLOW WINDS TO 20 KT THROUGH THE GULF OF 
PAPAGAYO DURING THE LATE NIGHT AND EARLY MORNING THROUGH 48 
HOURS.  

S OF PANAMA...A FAVORABLE INTERACTION OF A MID LEVEL TROUGH 
DEFORMATION WITH THE MONSOON TROUGH OVER THE SW CARIBBEAN HAS 
RESULTED IN AN ACTIVE MONSOON TROUGH OVER THE SW CARIBBEAN. 
INDICATIONS ARE THAT BACKGROUND FLOW WILL BE FAVORABLE FOR THIS 
AREA TO REMAIN ACTIVE...WITH THE POSSIBLE FORMATION OF A LOW 
PRESSURE CENTER WITHIN THE MONSOON TROUGH. THIS WILL RESULT IN 
ENHANCED SW MONSOONAL FLOW S OF PANAMA OVER THE NEXT COUPLE OF 
DAYS. 
$$

AL