000
AXPZ20 KNHC 062132
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC SAT APR 06 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 
1945 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
THE MONSOON TROUGH AXIS WAS ANALYZED FROM 04N77W TO 04N81W TO 
08N87W TO 07N91W. THE ITCZ AXIS WAS ANALYZED FROM 07N91W TO 
05N100W TO 06N114W TO 02N130W TO 02N140W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 82W 
AND 86W...WITHIN 150 NM S OF THE AXIS BETWEEN 90W AND 
100W...WITHIN 150 NM N OF THE AXIS BETWEEN 97W AND 123W...AND 
WITHIN 120 NM S OF THE AXIS BETWEEN 112W AND 123W.
 
...DISCUSSION...                                                 
GULF OF TEHUANTEPEC...THE 1616 UTC ASCAT PASS SHOWS THAT GALE 
CONDITIONS HAVE DIMINISHED AND N TO NE WINDS ARE DOWN TO A 
MODERATE TO FRESH BREEZE IN THE GULF OF TEHUANTEPEC. NE SWELL 
WILL CONTINUE TO KEEP SEAS OVER 8 FT SW OF THE GULF OF 
TEHUANTEPEC INTO EARLY SUN.

GULF OF PAPAGAYO...THE COLD FRONT THAT BROUGHT GALE CONDITIONS 
TO THE GULF OF TEHUANTEPEC WILL SLIDE SOUTHWARD ALONG THE E 
COAST OF NICARAGUA AND NORTHERN COSTA RICA OVERNIGHT TONIGHT. NE 
WINDS WILL BRIEFLY REACH A STRONG BREEZE BEHIND THE FRONT IN THE 
GULF OF PAPAGAYO DURING THE EARLY MORNING PEAK OF DRAINAGE FLOW 
OFF THE LAND SUN MORNING. WINDS WILL DIMINISH AFTER SUNRISE.
                                                
THE UPPER PATTERN CONTINUES TO FEATURE AN ANTICYCLONE OVER NW 
VENEZUELA THAT EXTENDS A RIDGE WESTWARD ALONG 07N TO 100W. UPPER 
DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS ENHANCING THE SCATTERED 
MODERATE CONVECTION ALONG THE MONSOON TROUGH E OF 100W DESCRIBED 
IN THE SECTION ABOVE. RELATIVELY ZONAL WESTERLY FLOW DOMINATES 
THE REMAINDER OF THE PACIFIC FORECAST AREA ALOFT...SAVE THE NW 
CORNER WHERE A SMALL UPPER LOW IS EVIDENT ON WATER VAPOR IMAGERY 
NEAR 21N139W AND WEAK EASTERLIES PREVAIL TO ITS N. THIS LOW IS 
EMBEDDED IN DRY AIR ALOFT. TROPICAL MOISTURE IS CONFINED S OF 
THE LOW WITHIN 240 NM OF THE 60 KT JET AXIS FROM 11N140W TO 
MAZATLAN MEXICO. THIS MOISTURE IS MANIFESTED PRIMARILY AS CIRRUS.

THE 1029 MB SUBTROPICAL SURFACE HIGH LIES NEAR 29N139W. THE 
PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND THE ITCZ IS 
FORCING FRESH TO STRONG NE TRADE WINDS FROM 10N TO 20N W OF 127W 
AS SEEN BY THE 1758 UTC ASCAT PASS. THE HIGH IS FORECAST TO 
STRENGTHEN SLIGHTLY AS IT MOVES AROUND 200-300 NM NORTHWESTWARD 
OVER THE NEXT 24 HOURS. THIS WILL SHIFT THE STRONGEST TRADES 
SLIGHTLY MORE WESTWARD IN RESPONSE. BY MON...THE HIGH WILL PULL 
FARTHER N OF THE AREA AND TRADE WINDS ARE EXPECTED TO DIMINISH 
TO A MODERATE TO FRESH BREEZE.

THE PRESSURE GRADIENT ON THE E SIDE OF THE SUBTROPICAL RIDGE IS 
ALSO FORCING FRESH TO STRONG WINDS N OF 26N ALONG THE COAST OF 
THE BAJA CALIFORNIA PENINSULA AS SEEN BY THE 1754 UTC ASCAT AND 
1424 UTC WINDSAT PASSES. FRESH TO STRONG NW WINDS WILL EXPAND AS 
FAR AS 330 NM AWAY FROM THE BAJA CALIFORNIA NORTE COAST SUN AS 
THE SUBTROPICAL RIDGE STRENGTHENS AS WELL AS MON WHEN A NORTHERN 
STREAM SYSTEM MOVES INTO THE WESTERN U.S. AND MAINTAINS THE 
STRONG PRESSURE GRADIENT. NW SWELL WILL COMBINE WITH NW WIND 
WAVES HERE...WITH SEAS EXPECTED TO REACH 13 FT BY MON AFTERNOON.

THE LEADING EDGE OF A NW SWELL TRAIN WITH PERIODS EXCEEDING 20 
SECONDS IS MOVING SOUTHWARD ALONG THE BAJA CALIFORNIA PACIFIC 
COAST. THE EASTERN EDGE OF THIS SWELL WILL CLIP THE CENTRAL 
MEXICAN COAST NEAR CABO CORRIENTES SUN NIGHT. SEAS ASSOCIATED 
WITH THIS SWELL TRAIN ARE AS HIGH AS 11 FT OVER NW WATERS WHERE 
THEY ARE EXPECTED TO SUBSIDE OVER THE NEXT 24 HOURS. 

$$
SCHAUER