000
AXPZ20 KNHC 042149 RRA
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC WED APR 03 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 
20300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N77W TO 08N82W TO 
05N89W TO 06N105W. ITCZ AXIS WAS ANALYZED FROM 06N105W TO 
02N130W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS  
WITHIN 210 NM N AND 120 NM S OF THE AXIS BETWEEN 83W AND 92W. 
SCATTERED MODERATE CONVECTION WAS WITHIN 60 NM EITHER SIDE OF 
THE AXIS BETWEEN 103W AND 108W AS WELL AS WITHIN 180 NM N OF 
THE AXIS BETWEEN 115W AND 126W.

...DISCUSSION...                                                
GULF OF TEHUANTEPEC...A COLD FRONT PASSING THROUGH THE SW GULF 
OF MEXICO WILL MOVE THROUGH CHIVELA PASS THIS EVENING AND BRING 
GALE FORCE N WINDS INTO THE GULF OF TEHUANTEPEC BY SUNRISE FRI. 
N WINDS WILL PERSIST THROUGH THE PASS UNTIL SAT WHEN WINDS IN 
THE SW GULF SHIFT SOUTHEASTERLY AS THE RIDGE BEHIND THE COLD 
FRONT PROGRESSES EASTWARD. THE GALE IS FORECAST TO END SAT AFTER 
SUNRISE WITH WINDS QUICKLY DIMINISHING BELOW A STRONG BREEZE IN 
THE AFTERNOON.
                                                
THE UPPER PATTERN CURRENTLY FEATURES AN ANTICYCLONE NEAR THE 
COLOMBIA/VENEZUELA BORDER THAT EXTENDS A RIDGE WESTWARD ALONG 
07N TO 95W. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS 
ENHANCING THE SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
DESCRIBED IN THE SECTION ABOVE. A LONG-WAVE TROUGH ALONG 101W 
EXTENDS INTO CENTRAL MEXICO AND A RIDGE TO ITS W LIES FROM 
ARIZONA THROUGH THE CENTRAL GULF OF CALIFORNIA TO 00N115W. A 
BAND OF MAINLY MID- TO UPPER-LEVEL MOISTURE MANIFESTED PRIMARILY 
BY CIRRUS IS FOUND N OF THE ITCZ BETWEEN THE RIDGE AXIS AND A 
WEAK UPPER TROUGH FROM 32N126W TO 26N130W. THE PATTERN IS 
PROGRESSIVE. THE WEAK TROUGH IS FORECAST TO RACE EASTWARD INTO 
THE WESTERN U.S. ON FRI AND LEAVE BEHIND AN UPPER LOW JUST NW OF 
THE FORECAST AREA BY SAT. MEANWHILE...THE LONG-WAVE TROUGH TO 
THE E WILL WEAKEN AS IT PASSES N OVER THE RIDGE IN SW WATERS. 

THE WEAKENED 1023 MB SUBTROPICAL SURFACE HIGH LIES NEAR 
27N140W...TO THE W OF THE SURFACE TROUGH FROM 32N125W TO 30N126W 
TO 24N132W ASSOCIATED WITH THE AFOREMENTIONED WEAK UPPER TROUGH 
EXPECTED TO MOVE INTO THE WESTERN U.S. THIS SURFACE TROUGH WILL 
DISSIPATE OVER THE FORECAST AREA BY FRI AS ITS IMPETUS ALOFT 
RACES EASTWARD AND THE SUBTROPICAL HIGH BUILDS IN PLACE. THE 1840 
UTC ASCAT PASS SHOWS TRADE WINDS ARE A MODERATE TO FRESH NE 
BREEZE OVER WESTERN WATERS. THEY ARE EXPECTED TO INCREASE TO A 
STRONG BREEZE STARTING FRI AS THE HIGH BUILDS. THE PRESSURE 
GRADIENT WILL ALSO BUILD ALONG THE E EDGE OF THE ZONAL RIDGE 
AXIS. THIS WILL ALLOW FRESH TO STRONG NW WINDS TO BECOME 
ESTABLISHED WITHIN 120 NM W OF THE BAJA CALIFORNIA NORTE COAST 
FRI AND SAT.

NW SWELL WITH PERIODS EXCEEDING 20 SECONDS WILL MOVE INTO NW 
WATERS ON FRI. SEAS THERE ARE EXPECTED TO BUILD TO 11 FT BY SAT 
MORNING...WITH THE LEADING EDGE OF THE SWELL MOVING 
SOUTHEASTWARD....REACHING THE BAJA CALIFORNIA NORTE COAST ON SAT.

$$
SCHAUER