000
AXPZ20 KNHC 052133
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC THU APR 04 2013

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 
2015 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N82W TO 04N91W TO 
05N97W TO 04N100W. THE ITCZ AXIS WAS ANALYZED FROM 04N100W TO 
01N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS 
S OF THE AXIS TO 04N BETWEEN 82W AND 86W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 120 NM N OF THE AXIS BETWEEN 86W AND 89W 
AS WELL AS BETWEEN 92W AND 96W. 
                                             
...DISCUSSION...                                                
GULF OF TEHUANTEPEC...INFRARED SATELLITE IMAGERY SHOWS A COLD 
POOL OF AIR HAS MOVED INTO THE GULF OF TEHUANTEPEC AND NORTHERLY 
FLOW AT SALINA CRUZ PICKED UP TO 30 KT AT 1800 UTC. THIS WAS 
SUFFICIENT EVIDENCE TO BEGIN A GALE WARNING FOR THE GULF OF 
TEHUANTEPEC. N WINDS WILL PERSIST THROUGH CHIVELA PASS UNTIL 
EARLY SAT WHEN WINDS IN THE SW GULF WILL SHIFT SOUTHEASTERLY AS 
THE RIDGE BEHIND THE COLD FRONT PROGRESSES EASTWARD. THE GALE IS 
FORECAST TO END AROUND SUNRISE SAT WITH WINDS QUICKLY 
DIMINISHING BELOW A STRONG BREEZE BY SAT EVENING. NE SWELL WILL 
CONTINUE TO KEEP SEAS OVER 8 FT SW OF THE GULF OF TEHUANTEPEC 
INTO EARLY SUN.
                                                
THE UPPER PATTERN CURRENTLY FEATURES AN ANTICYCLONE OVER NW 
VENEZUELA THAT EXTENDS A RIDGE WESTWARD ALONG 06N TO 95W. UPPER 
DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS ENHANCING THE SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION ALONG THE MONSOON 
TROUGH DESCRIBED IN THE SECTION ABOVE. THE LONG-WAVE UPPER 
TROUGH SUPPORTING THE COLD FRONT THAT BROUGHT GALE FORCE WINDS 
TO TEHUANTEPEC IS FOUND FROM THE NE GULF OF MEXICO THROUGH THE 
GULF OF TEHUANTEPEC TO 10N95W. IT IS BEGINNING TO MOVE OVER THE 
UPPER RIDGE TO ITS SE. ANOTHER RIDGE AXIS LIES TO ITS W FROM THE 
TEXAS BIG BEND TO 10N110W. A BAND OF MAINLY MID- TO UPPER-LEVEL 
MOISTURE MANIFESTED PRIMARILY BY CIRRUS IS FOUND N OF 10N W OF 
THE RIDGE AXIS...EXTENDING THROUGH THE SOUTHERN GULF OF 
CALIFORNIA AND INTO NORTHERN MEXICO. MOISTURE ASSOCIATED WITH 
THIS BAND HAS DISSIPATED CONSIDERABLY OVER THE PAST 24 HOURS. 

THE 1026 MB SUBTROPICAL SURFACE HIGH LIES NEAR 29N132W. THE HIGH 
HAS STRENGTHENED SINCE YESTERDAY AND THE 1820 UTC ASCAT PASS 
SHOWS TRADE WINDS HAVE INCREASED TO A STRONG NE BREEZE OVER 
WESTERN WATERS. TRADES WILL REMAIN FRESH TO STRONG THROUGH THE 
WEEKEND AS THE SUBTROPICAL RIDGE CONTINUES TO BUILD. THE 
PRESSURE GRADIENT HAS ALSO STRENGTHENED ALONG THE E EDGE OF THE 
RIDGE AXIS ALLOWING FRESH TO STRONG NW WINDS TO BECOME 
ESTABLISHED W OF THE BAJA CALIFORNIA PENINSULA. THESE WINDS ARE 
EXPECTED TO EXPAND OUT TO 300 NM AWAY FROM THE COAST ON SUN.

NW SWELL WITH PERIODS EXCEEDING 20 SECONDS HAS MOVED INTO NW 
WATERS. SEAS THERE ARE EXPECTED TO BUILD TO 11 FT BY SAT 
MORNING. THE LEADING EDGE OF THE SWELL WILL PROGRESS 
SOUTHEASTWARD....SPREADING SOUTHWARD ALONG THE BAJA CALIFORNIA 
PACIFIC COAST ON SAT.

$$
SCHAUER