000
AXPZ20 KNHC 090405
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI DEC 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 
0315 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 09N84W TO 07N94W WHERE LOW LEVEL 
WINDS SUGGEST THAT THE INTERTROPICAL CONVERGENCE ZONE 
BEGINS...AND EXTENDS TO 06N103W TO 08N115W TO 10N126W TO 
07N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 
120 NM N OF THE ITCZ BETWEEN 126W-129W.

...DISCUSSION...

A STRONG BLOCKING UPPER LEVEL PATTERN IS EVIDENT ON WATER VAPOR 
IMAGERY THIS MORNING ACROSS THE BROADER REGION N OF 08N BETWEEN 
90W AND 145W ANCHORED BY AN UPPER LEVEL ANTICYCLONIC CIRCULATION 
CENTERED NEAR 12N118W. AN UPPER LEVEL TROUGH IS LOCATED WEST OF 
THE REGION WITH AXIS ALONG 30N142W TO 10N152W. STRONG AND 
DIFFLUENT SOUTHWESTERLY MIDDLE TO UPPER LEVEL FLOW ROUNDS THE 
BASE OF THIS TROUGH AND COVERS A BROAD ZONE OF THE DISCUSSION 
AREA GENERALLY FROM NORTH OF THE ITCZ AXIS NEAR 07N TO 27N W OF 
125W. THIS AREA OF DIFFLUENT FLOW WAS PROVIDING A FAVORABLE 
ENVIRONMENT FOR WIDELY SCATTERED DEEP CONVECTION FROM 08N TO 22N 
W OF 130W.

OVER THE NORTHEASTERN PERIPHERY OF THE UPPER LEVEL 
ANTICYCLONE...DRY AND STABLE ATMOSPHERIC CONDITIONS PREVAIL E OF 
115W...EXCEPT IN THE VICINITY OF A WEAK TUTT AXIS EXTENDING FROM 
OVER CENTRAL AMERICA NEAR 14N86W TO 04N101W OVER THE MONSOON 
TROUGH AXIS ACROSS THE FAR TROPICAL E PACIFIC.

THE OVERALL BROAD SCALE PATTERN WILL CHANGE ONLY MODESTLY ACROSS 
THE DISCUSSION AREA THROUGH THE NEXT 24-48 HOURS AS THIS BROAD 
LATITUDE RIDGING PREVAILS...CENTERED ON A PERSISTENT UPPER LEVEL 
HIGH NEAR 13N118W AND EXTENDING N TO 30N. THIS PATTERN WILL 
CONTINUE TO FORCE SHORTWAVE ENERGY LOCATED TO THE WEST AND 
NORTHWEST OVER THE NORTHWARD EXTENT OF THE RIDGE AND REMAIN 
OUTSIDE OF THE AREA...WITH NO FRONTAL BOUNDARIES EXPECTED TO 
CROSS S OF 32N.

GULF OF TEHUANTEPEC...HIGH PRES BUILDING SOUTHWARD ALONG THE 
SIERRA MADRE OF MEXICO HAS INCREASED THE PRES GRADIENT BETWEEN 
THE NORTHERN COAST OF THE ISTHMUS OF TEHUANTEPEC AND ITS 
SOUTHERN TERMINUS BEHIND A STALLED FRONT OVER THE NW CARIBBEAN 
SEA. THE GAP FLOW REACHED GALE FORCE YESTERDAY AND IS NOW 
DIMINISHING. DOWNSTREAM SEAS CONTINUE IN THE 8 TO 13 FT RANGE 
AND SHOULD SLOWLY SUBSIDE TO 8-11 FT THROUGH FRIDAY. NEAR THE 
END OF THE 48 HOUR FORECAST PERIOD HOWEVER...REINFORCING SURFACE 
RIDGING OVER THE SW GULF OF MEXICO WILL RE-ENERGIZE WINDS TO 
GALE FORCE ONCE AGAIN SATURDAY MORNING.

FARTHER WEST...THE PRES GRADIENT BETWEEN A TROUGH JUST W OF THE 
AREA AND HIGH PRES RIDGING OVER THE NW AND N PORTIONS WILL 
MAINTAIN NE TO E WINDS OF 20-25 KT OVER AN AREA FROM 08N TO 22N 
W OF 124W WITH SEAS 8 TO 11 FT THROUGH THE NEXT 24 HOURS...AND 
FROM 12N TO 23N W OF 121W IN 48 HOURS. ACTIVE CONVECTION WILL 
LIKELY PERSIST ACROSS THIS AREA THROUGH SATURDAY MORNING DUE TO 
FAVORABLE UPPER LEVEL DIFFLUENCE AND CONTINUED LOW LEVEL 
CONVERGENCE ASSOCIATED WITH THE FRESH TO STRONG TRADES.

GULF OF PAPAGAYO...NE 20 KT WINDS WILL CONTINUE TO PULSE UP AND 
DOWN DOWNWIND OF THE GULF OF PAPAGAYO THROUGH THE NEXT 48 HOURS 
IN THE LATE NIGHT AND EARLY MORNING HOURS DURING PEAK DRAINAGE 
FLOW OFF OF CENTRAL AMERICA. THESE OCCURRENCES SHOULD NOT LAST 
LONG ENOUGH TO BE INCLUDED IN THE HIGH SEAS FORECAST.

$$
AGUIRRE