000
AXPZ20 KNHC 082128
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE NOV 08 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 09N84W TO 07.5N101W. THE ITCZ AXIS EXTENDS FROM 
07.5N101W TO 11N113W...THEN IS DISRUPTED BY A SURFACE TROUGH 
FROM 14N114W AND 09N117W. THE ITCZ THEN RESUMES FROM 09.5N119W 
TO 08N134W TO 09N140W. SCATTERED MODERATE TO STRONG CONVECTION 
WAS NOTED WITHIN 60 NM S OF ITCZ AXIS BETWEEN 109W AND 111W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 
60 NM S OF ITCZ AXIS BETWEEN 119W 128W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 30 NM S AND 60 NM N OF AXIS BETWEEN 
131W AND 135W. 

...DISCUSSION...

HIGH PRESSURE 1027 MB IS CENTERED N OF THE AREA NEAR 32N130W 
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 24N 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 20 
KT 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 WILL WEAKEN WITH 
FRESH 20 KT TRADES LIMITED TO THE AREA FROM 12N TO 18N W OF 137W 
BY THU AFTERNOON. DESPITE THE WINDS DIMINISHING...SOUTHERLY 
SWELL WILL MAINTAIN SEAS TO 9 FT OVER THE AREA S OF 20N W OF 
103W AND S OF 10N BETWEEN 91W AND 103W. 

AS THE HIGH PRESSURE CENTER SHIFTS EASTWARD...THE PRESSURE 
GRADIENT OVER THE GULF OF CALIFORNIA WILL TIGHTEN...WITH NW 
WINDS EXPECTED TO INCREASE TO 25 KT IN THE GULF OF CALIFORNIA BY 
WED AFTERNOON. AS THE HIGH PRESSURE CENTER WEAKENS...THE 
GRADIENT WILL RELAX WITH FRESH WINDS LIMITED TO N OF 30N OVER 
THE GULF OF CALIFORNIA BY THU AFTERNOON. 

THE EASTWARD SHIFT OF THE HIGH PRESSURE CENTER MENTIONED ABOVE 
WILL ENABLE A COLD FRONT TO MOVE INTO THE AREA WED NIGHT. THE 
FRONT WILL EXTEND FROM 30N131W TO 25N140W BY THU AFTERNOON. 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