000
AXPZ20 KNHC 311518
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE MAY 31 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1345 UTC.
 
...ITCZ...
INTERTROPICAL CONVERGENCE ZONE IS ANALYZED FROM 10N86W TO 14N98W 
TO 07N115W TO 06N140W. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION LIES WITHIN 150 NM N OF THE ITCZ AXIS BETWEEN 92W AND 
101W AND WITHIN 150 NM S OF THE ITCZ AXIS BETWEEN 97W AND 101W. 
ISOLATED MODERATE CONVECTION IS ELSEWHERE FROM 03N TO 14N 
BETWEEN 86W AND 107W. ISOLATED MODERATE ALSO LIES WITHIN 120 NM 
N OF THE ITCZ AXIS BETWEEN 117W AND 120W AND WITHIN 120 NM S OF 
THE ITCZ AXIS BETWEEN 114W AND 117W.

...DISCUSSION...
A POSITIVELY TILTED LONGWAVE TROUGH EXTENDS FROM A DEEP LAYERED 
LOW WELL N OF THE AREA OFF THE PACIFIC NW COAST OF THE UNITED 
STATES TO AN UPPER LOW JUST E OF HAWAII BUT W OF THE FORECAST 
AREA NEAR 23N152W. A COLD FRONT ASSOCIATED WITH THE DEEP LAYERED 
LOW IS WEAKENING OVER THE AREA N OF 29N W OF 130W. THIS FRONT 
WILL DISSIPATE LATER TODAY...BUT NW SWELL ASSOCIATED WITH THE 
SYSTEM WILL MOVE INTO THE AREA AND REACH THE SOUTHERN CALIFORNIA 
COAST BY THU MORNING. 

THIS COLD FRONT HAS WEAKENED THE SUBTROPICAL RIDGE THAT STEMS 
FROM A 1032 MB HIGH PRES SYSTEM NEAR 38N150W AND EXTENDS SE OF 
THE FRONT FROM 29N128W TO 16N114W. THE SUBTROPICAL HIGH WILL 
REMAIN ALMOST STATIONARY OVER THE NEXT FEW DAYS...BUT THE 
RIDGING EXTENDING INTO THE FORECAST AREA WILL STRENGTHEN AS THE 
COLD FRONT DISSIPATES AND THE DEEP LAYERED TROUGH TO THE N MOVES 
EASTWARD. NE TRADE WINDS THAT ARE CURRENTLY CONFINED W OF 130W 
WILL EXPAND EASTWARD WED INTO THU MORNING AS A RESULT. IN 
ADDITION...THE FRESH NW TO N WINDS SEEN CLOSE TO THE BAJA 
CALIFORNIA NORTE COAST TODAY WILL EXPAND TO THE W AND INCREASE 
TO STRONG OVER NE WATERS BY THU.

FAIR WEATHER PREVAILS OVER THE REGION DOMINATED BY THE 
SUBTROPICAL RIDGE WITH SCATTERED TO BROKEN STRATOCUMULUS FOUND 
IN MUCH OF THE AREA N OF 13N W OF 115W. A BAND OF CIRRUS 
OVERLAYS THE LOWER CLOUDS WITHIN 240 NM OF A LINE FROM 20N140W 
TO THE BAJA CALIFORNIA NORTE COAST NEAR 28N. THIS CIRRUS IS THE 
RESULT OF MOISTURE TRANSPORT FROM THE TROPICS S OF HAWAII BY A 
40-50 KT SOUTHWESTERLY UPPER JET. DEEP CONVECTION IS CONFINED S 
OF 16N AND E OF 130W...WITH THE STRONGEST CONVECTION FOUND S OF 
PANAMA. THIS SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
FOUND N OF 03N E OF 84W IS BEING ENHANCED BY UPPER DIFFLUENCE 
BETWEEN SOUTHWESTERLY FLOW TO THE N ON THE LEADING EDGE OF A 
POSITIVELY TILTED BROAD TROUGH OVER THE NW CARIBBEAN AND 
EASTERLY FLOW TO THE S FOUND ON THE N SIDE OF AN UPPER LOW.

FRESH SOUTHWESTERLY WINDS WERE FOUND BY THE 0328 UTC ASCAT PASS 
IN THE AREA FROM 04N TO 11N BETWEEN 95W AND THE EDGE OF THE 
SWATH NEAR 100W. SHIP 3FMH7 NEAR 11N98W CONFIRMED THESE 
CONDITIONS. THE NUMERICAL WEATHER PREDICTION MODELS DO NOT 
CAPTURE THE CURRENT WIND FIELD SUFFICIENTLY COMPARED TO THESE 
OBSERVATIONS. HOWEVER...THEY DO SUGGEST A GENERAL REDUCTION IN 
THE SIZE OF THE WIND FIELD OVER THE NEXT FEW DAYS. THE MODELS 
ALSO SEEM TO BE HAVING A HARD TIME PICKING UP THE REASONABLY 
WELL DEFINED MID LEVEL CIRCULATION NEAR 09N109W...WITH MOST OF 
THE MODELS PLACING THE SYSTEM TOO FAR TO THE E. SOME OF THE 
MODELS SUGGEST THAT THIS SYSTEM COULD SEE SOME DEVELOPMENT LATE 
IN THE WEEK...BUT CONFIDENCE IS CURRENTLY LOW.

LARGE LONG PERIOD S SWELLS WITH SEAS OF 8-11 FT ARE PROPAGATING 
ACROSS THE ENTIRE BASIN E OF 130W. SEAS WILL GRADUALLY SUBSIDE 
BELOW ADVISORY CRITERIA BY THU. UNUSUALLY HIGH BREAKERS AND 
HEAVY SURF WILL CONTINUE ALONG THE ENTIRE PACIFIC COAST OF 
MEXICO AND CENTRAL AMERICA TODAY AND WED.

A SURFACE TROUGH IN THE WESTERN CARIBBEAN WILL SHIFT W AND START 
TO FUNNEL WINDS THROUGH THE CHIVELAS PASS INTO THE GULF OF 
TEHUANTEPEC TONIGHT. WINDS WILL QUICKLY BECOME STRONG IN THE 
GULF OF TEHUANTEPEC BY EARLY WED MORNING CONTINUING THROUGH THE 
END OF THE PERIOD EARLY THU. WINDS ARE EXPECTED TO STAY JUST 
BELOW GALE FORCE...BUT BRIEF GALE FORCE WINDS ARE POSSIBLE.

$$
SCHAUER