000
AXPZ20 KNHC 090307
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED NOV 09 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH 09.5N84W TO 08N103W. THE ITCZ AXIS EXTENDS FROM 
08N103W TO 12N113W...THEN IS DISRUPTED BY A SURFACE TROUGH FROM 
14N115W TO 10N120W. THE ITCZ THEN RESUMES FROM 09.5N123W TO 
08.5N133W TO 09N140W. SCATTERED MODERATE CONVECTION WAS NOTED 
WITHIN 90 NM S OF AXIS BETWEEN 110W AND 112W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 60 NM OF AXIS W OF 135W. 

...DISCUSSION...

HIGH PRESSURE 1028 MB IS CENTERED N OF THE AREA NEAR 32N128W 
WITH SURFACE RIDGE EXTENDING SE TO NEAR 17N108W. THE PRESSURE 
GRADIENT BETWEEN THIS FEATURE AND THE ITCZ IS MAINTAINING FRESH 
20 KT TRADE WINDS FROM 08N TO 22N W OF 115W WITH COMBINED SEAS 
REACHING 11 FT IN NE SWELL. THE PRESSURE GRADIENT BETWEEN THE 
SURFACE RIDGE AND A TROUGH OVER MEXICO IS MAINTAINING FRESH TO 
STRONG NW WINDS ACROSS MUCH OF THE GULF OF CALIFORNIA.  

THE HIGH PRESSURE CENTER WILL SHIFT E AND WEAKEN OVER THE NEXT 
48 HOURS. AS A RESULT...THE PRESSURE GRADIENT THAT CREATED THE 
FRESH TRADES WILL LOOSEN AND TRADES WILL DIMINISH BELOW 20 KT  
BY THU EVENING. DESPITE THE WINDS DIMINISHING...SOUTHERLY SWELL 
WILL MAINTAIN SEAS TO 9 FT OVER MUCH OF THE AREA S OF 20N W OF 
100W. AS THE HIGH PRESSURE RIDGE WEAKENS...THE GRADIENT OVER THE 
GULF OF CALIFORNIA WILL ALSO RELAX WITH WINDS DIMINISHING BELOW 
20 KT OVER THE GULF OF CALIFORNIA BY THU EVENING. 

THE EASTWARD SHIFT OF THE HIGH PRESSURE CENTER MENTIONED ABOVE 
WILL ENABLE A COLD FRONT TO MOVE INTO THE AREA WED NIGHT. THE 
MOST SIGNIFICANT MARINE IMPACT FROM THE FRONT WILL BE LARGE NW 
SWELL THAT WILL SWEEP INTO NW PORTION AND SPREAD SE THROUGH THE 
REST OF THE WEEK. EXPECT LEADING EDGE OF SWELL TO ARRIVE 
IMMEDIATELY BEHIND THE FRONT WED NIGHT THEN RAPIDLY BUILD TO 
17-18 IN NW PART BY THU NIGHT. WW3 WAVE MODEL SHOWS ANOTHER 
SURGE OF NW SWELL CROSSING 30N ON FRIDAY...WITH SEAS BUILDING TO 
20-24 FT N OF 28N BEHIND THE FRONT AS IT PUSHES FURTHER E TOWARD 
BAJA CALIFORNIA.

GAP WINDS...
A COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS GULF COAST EARLY 
WED AND MOVE RAPIDLY ACROSS THE GULF OF MEXICO THROUGH LATE THU. 
WINDS BEHIND THE FRONT WILL START TO FUNNEL THROUGH THE CHIVELA 
PASS INTO THE GULF OF TEHUANTEPEC BY WED NIGHT. WINDS ARE 
EXPECTED TO REACH GALE FORCE BY THU AFTERNOON. PEAK WINDS AROUND 
45-50 KT CAN BE EXPECTED LATE THU NIGHT/EARLY FRI MORNING 
ASSOCIATED WITH THIS GAP WIND EVENT.

$$
AL