000
AXPZ20 KNHC 050242
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N77W TO 08N82W TO 
05N90W TO 07N106W. THE ITCZ AXIS WAS ANALYZED FROM 07N106W TO 
02N130W. SCATTERED MODERATE CONVECTION WITHIN 45 NM N AND 90 NM 
S OF THE AXIS BETWEEN 81W AND 93W EXCEPT WITHIN 150 NM S OF THE 
AXIS BETWEEN 86W AND 92W. SCATTERED MODERATE CONVECTION WITHIN 
60 NM N AND 120 NM S OF THE AXIS BETWEEN 104W AND 110W. 

...DISCUSSION...                                                
GULF OF TEHUANTEPEC...NORTHERLY FLOW BEHIND A GULF OF MEXICO 
COLD FRONT HAS MOVED THROUGH CHIVELA PASS THIS EVENING. N WINDS 
TO 25 KT WERE OBSERVED IN THE GULF OF TEHUANTEPEC BY THE 1852 
UTC OSCAT PASS. WINDS ARE EXPECTED TO INCREASE TO GALE FORCE 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 AROUND SUNRISE SAT 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 CONVECTION ALONG THE MONSOON 
TROUGH DESCRIBED IN THE SECTION ABOVE. A LONG-WAVE TROUGH IS 
FOUND FROM THE NW GULF OF MEXICO THROUGH MEXICO CITY TO 00N103W 
AND A RIDGE TO ITS W LIES FROM THE U.S. FOUR CORNERS THROUGH THE 
SOUTHERN GULF OF CALIFORNIA TO 00N114W. A BAND OF MAINLY MID- TO 
UPPER-LEVEL MOISTURE MANIFESTED PRIMARILY BY CIRRUS IS FOUND N 
OF THE ITCZ JUST W OF THE RIDGE AXIS AND WELL E OF A WEAK UPPER 
TROUGH FROM 32N123W TO 26N127W. 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 1022 MB SUBTROPICAL SURFACE HIGH LIES NEAR 
28N137W...TO THE W OF THE SURFACE TROUGH FROM 32N122W TO 29N123W 
ASSOCIATED WITH THE AFOREMENTIONED WEAK UPPER TROUGH EXPECTED TO 
MOVE INTO THE WESTERN U.S. THIS SURFACE TROUGH WILL DISSIPATE 
OVER THE FORECAST AREA OVERNIGHT 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 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. THE LEADING EDGE OF THE SWELL WILL PROGRESS 
SOUTHEASTWARD....REACHING THE BAJA CALIFORNIA NORTE COAST ON SAT.

$$
SCHAUER