000
AXPZ20 KNHC 271609
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT NOV 27 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 08N78W TO LOW 
PRES NEAR 09N98W TO A SECOND LOW PRES NEAR 11N109W TO 10N132W TO 
11N140W. SCATTERED MODERATE CONVECTION WITHIN 60 NM OF LOW 
CENTERS.  

...DISCUSSION...
W OF 110W...SURFACE RIDGING N OF 25N CONTINUES TO WEAKEN IN 
ADVANCE OF A COLD FRONT THAT EXTENDS FROM CENTRAL CALIFORNIA TO 
31N140W. A STATIONARY UPPER LOW CENTERED REMAINS PARKED NEAR 
20N147W...WITH AN ASSOCIATED SURFACE TROUGH ALONG 142W S OF 23N. 
THE PRESSURE GRADIENT REMAINS TIGHT ENOUGH BETWEEN THE TROUGH 
AND THE WEAKENING RIDGE TO SUPPORT FRESH TO STRONG 
TRADES...GENERALLY FROM 13N TO 23N W OF 130W...AS NOTED BY 
SHIP...ASCAT...AND WINDSAT DATA FROM THE PAST SEVERAL HOURS. THE 
SURFACE TROUGH WILL DAMPEN OUT OVER THE NEXT 48 HOURS AS THE 
UPPER TROUGH OPENS UP AND LIFTS OUT TO THE NE IN PHASE WITH AN 
UPPER SHORT WAVE TROUGH MOVING INTO THE NE PACIFIC. THE FRESH 
TRADES WILL PERSIST HOWEVER MAINLY N OF 10N W OF 120W THROUGH 
EARLY NEXT WEEK AS HIGH PRES BUILDS INTO THE AREA FROM THE NORTH 
BEHIND THE ADVANCING COLD FRONT. THE FRONT WILL PUSH SOUTH AND 
EXTEND FROM NORTHERN BAJA TO 28N126W BY 12Z SUN...THEN WASH OUT 
FROM CENTRAL BAJA TO 25N128W BY SUN EVENING. NW TO N WINDS 20 TO 
25 KT WILL FOLLOW THE FRONT DOWN THE BAJA COAST SUN...FOLLOWED 
BY 8 TO 10 FT NW SWELL. FURTHER SOUTH...A WEAK TROUGH ALONG THE 
ITCZ AT 118W DRIFTING W. A 1011 MB LOW PRES IS CENTERED ALONG 
ITCZ EAST OF THE TROUGH NEAR 11N110W. EXPECT CLUSTER OF SHOWERS 
AND TSTMS TO PERSIST NEAR THESE FEATURES AS THEY MOVE SLOW W 
OVER THE NEXT 48 HOURS...WITH 20 KT FLOW WITHIN 120 NM TO N. 

E OF 110W...THE MAIN ISSUE IS THE ONSET OF GALE FORCE WINDS 
THROUGH THE GULF OF TEHUANTEPEC...AS COLDER...DENSER AIR FILTERS 
DOWN THE WESTERN GULF OF MEXICO AND THROUGH THE ISTHMUS OF 
TEHUANTEPEC. THE GALE FORCE WINDS WILL PERSIST INTO 
TONIGHT...THEN DIMINISH SUN AS HIGH PRES N OF THE AREA RAPIDLY 
SHIFTS EAST. FURTHER SOUTH...GAP WINDS THROUGH THE GULF OF 
PAPAGAYO WILL PULSE TO 20 KT IN THE EARLY MORNING HOURS...THE 
COMBINATION OF LOCAL NOCTURNAL DRAINAGE FLOW AND SOME ADDED 
ENHANCEMENT FROM EASTERLY GRADIENT FLOW FROM THE SW CARIBBEAN. 
LOOKING AHEAD...A STRONGER COLD FRONT WILL PUSH THROUGH THE 
WESTERN GULF OF MEXICO BY MIDWEEK...AND WILL DELIVER ANOTHER 
ROUND OF GALE FORCE WINDS TO THE GULF OF TEHUANTEPEC...POSSIBLY 
APPROACHING STORM STRENGTH WED.

GULF OF CALIFORNIA...A 04Z ASCAT PASS SHOWS NW WINDS 20 KT OVER 
THE SOUTHERN GULF OF CALIFORNIA. THE WINDS ACROSS THE GULF ARE 
DIMINISHING AS HIGH PRES OVER THE GREAT BASIN WEAKENS AND SHIFTS 
EAST. EXPECT A NEW ROUND OF FRESH TO STRONG NW FLOW IN THE GULF 
OF CALIFORNIA BY EARLY MON AS HIGH PRES BUILDS BEHIND A WEAK 
COLD FRONT THAT WILL MOVE INTO THE AREA AND DISSIPATE SUN.

$$
CHRISTENSEN