000
AXPZ20 KNHC 070259
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU APR 07 2011

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 0300 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 07N80W 
TO 03N92W TO 05N115W TO 06N140W. SCATTERED MODERATE CONVECTION 
WITHIN 45 NM S OF AXIS BETWEEN 85W AND 87W. SCATTERED MODERATE 
CONVECTION WITHIN 60 NM S OF AXIS W OF 135W.

...DISCUSSION...

UPPER RIDGING OVER THE N CENTRAL PACIFIC ALONG WITH AN 
ASSOCIATED 1043 MB HIGH PRES CENTERED NEAR 40N150W ARE DRIFTING 
SLOWLY E. THIS FOLLOWS A VIGOROUS UPPER SHORT WAVE TROUGH NOW 
MOVING OVER THE NORTHERN BAJA COAST...WHERE A SHARP SURFACE 
TROUGH IS NOTED ALONG THE GULF OF CALIFORNIA. SW WINDS WILL 
INCREASE OVER THE FAR NORTHERN PORTION OF THE GULF OF CALIFORNIA 
THROUGH FRI. THE SHORT WAVE TROUGH WILL LIFT OUT TONIGHT AHEAD 
OF A LONG WAVE TROUGH DIGGING INTO THE GREAT BASIN THAT IS 
ALREADY DELIVERING STRONG NW WINDS ALONG THE WEST COAST OF THE 
U.S. INCLUDING GALE FORCE WINDS ALONG THE CENTRAL CALIFORNIA 
COAST. THE STRONGER N WINDS BETWEEN THE ADVANCING HIGH PRES AND 
THE COAST WILL SHIFT S OF 32N TO AS FAR S AS 27N E OF 130W BY 
THU. AS THE HIGH PRES SHIFT FURTHER E...WINDS WILL VEER MORE NE 
ACROSS THE BASIN W OF 110W. RECENT SHIP OBSERVATIONS ALONG WITH 
A 17Z JASON ALTIMETER PASS SHOW SEAS OF 8 TO 12 FT...MAINLY IN 
NW SWELL...N OF 20N W OF 125W. 

S OF 20N...TRADE WINDS REMAIN RELATIVELY LIGHT...BUT WILL 
GRADUALLY INCREASE W OF 120W THROUGH FRI AS THE RIDGE BUILDS N 
OF THE AREA. CROSS-EQUATORIAL SW SWELL IS GRADUALLY DIMINISHING 
S OF 12N BETWEEN 95W AND 125W.

GULF OF TEHUANTEPEC...LAND BASED OBSERVATIONS NEAR SALINA CRUZ 
INDICATE FRESH N FLOW IS STILL PUSHING THROUGH THE ISTHMUS INTO 
ADJACENT WATERS. THIS WILL DIMINISH TO BELOW 20 KT OVERNIGHT
AS THE RELATIVELY COOLER AIRMASS OVER THE SW GULF OF MEXICO 
MODIFIES. SEAS OF 8 TO 10 FT WITH NE SWELL WILL GRADUALLY 
SUBSIDE AS WELL THROUGH EARLY THU.

GULF OF PAPAGAYO...THE PRES GRADIENT BETWEEN RIDGING OVER THE 
GULF OF MEXICO THROUGH SOUTHERN MEXICO AND TROUGHING OVER NW 
SOUTH AMERICA IS GENERATING 20 TO 25 KT E WINDS AS NOTED BY 
RECENT SHIP OBSERVATIONS AND EARLIER ASCAT DATA. WINDS WILL 
DIMINISH BACK TO 20 KT BY FRI MORNING AS THE FRONT DISSIPATES.

$$
CHRISTENSEN