000
AXPZ20 KNHC 040245
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 
0115 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N77W TO 10N84W TO 
04N97W. THE ITCZ AXIS WAS ANALYZED FROM 04N97W TO 05N105W TO 
03N125W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS 
WITHIN 270 NM S OF THE AXIS BETWEEN 84W AND 91W.

...DISCUSSION...                                               
THE UPPER PATTERN CURRENTLY FEATURES A LONG-WAVE TROUGH ALONG 
103W WITH WEAK RIDGING TO ITS E AND A MORE AMPLIFIED RIDGE TO 
ITS W. AN UPPER LOW LIES NW OF THE FORECAST AREA NEAR 40N140W. 
AN UPPER JET ON THE SE SIDE OF THE LOW MEETS UP WITH THE 
SOUTHERN STREAM UPPER JET OVER WATERS W OF 125W AND N OF 10N. 
THIS MERGED JET IS TRANSPORTING TROPICAL MOISTURE INTO THE 
FORECAST AREA. MULTI-LEVELED CLOUDS AND SCATTERED SHOWERS LIE 
BETWEEN 120W AND A LINE FROM 13N140W TO 32N127W. THE PATTERN IS 
PROGRESSIVE. THE UPPER LOW IS DRAGGING A NEGATIVELY TILTED 
TROUGH THROUGH NORTHERN WATERS THAT WILL WEAKEN AND RACE 
EASTWARD INTO THE WESTERN U.S. ON FRI. MEANWHILE...THE LONG-WAVE 
TROUGH WILL MOVE EASTWARD ACROSS MEXICO AND STRETCH FROM THE 
GULF OF TEHUANTEPEC TO 05N100W BY FRI EVENING.

THE WEAKENED 1020 MB SUBTROPICAL SURFACE HIGH LIES NEAR 28N124W. 
A COLD FRONT ASSOCIATED WITH THE AFOREMENTIONED UPPER LOW WAS 
ANALYZED FROM 32N130W TO 30N131W TO 21N140W. THIS WEAK COLD 
FRONT WILL EDGE SLIGHTLY FARTHER EASTWARD AS IT DISSIPATES 
OVERNIGHT. THE SUBTROPICAL HIGH WILL MERGE WITH HIGH PRES BEHIND 
THE COLD FRONT...REORIENTING THE RIDGE AXIS SOUTHWARD ALONG 25N 
W OF 125W THU. THE CONSOLIDATED HIGH WILL STRENGTHENING OVER NW 
WATERS ON FRI. TRADE WINDS WILL REMAIN A MODERATE TO FRESH 
BREEZE THROUGH LATE FRI AS A RESULT OF THE WEAK PRESSURE 
GRADIENT BETWEEN THE SUBTROPICAL HIGH AND THE ITCZ. 
HOWEVER...THE GRADIENT WILL BUILD ALONG THE E EDGE OF THE ZONAL 
RIDGE ON FRI. THIS WILL ALLOW FRESH TO STRONG NW WINDS TO BECOME 
ESTABLISHED WITHIN 150 NM W OF THE BAJA CALIFORNIA NORTE COAST.
 
A COLD FRONT PASSING THROUGH THE SW GULF OF MEXICO LATE THU WILL 
MOVE THROUGH CHIVELA PASS AND BRING STRONG N WINDS INTO THE GULF 
OF TEHUANTEPEC OVERNIGHT THU NIGHT. WINDS ARE EXPECTED TO REACH 
NEAR GALE FORCE ON FRI WITH SEAS BUILDING TO 12 FT. 

NW SWELL WITH PERIODS EXCEEDING 20 SECONDS WILL MOVE INTO NW 
WATERS ON FRI. SEAS THERE ARE EXPECTED TO BUILD TO 9 FT BY FRI 
AFTERNOON.

$$
SCHAUER