000 AXPZ20 KNHC 070240 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN APR 07 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 0045 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 09N78W TO 08N83W TO 05N93W. THE ITCZ AXIS WAS ANALYZED FROM 05N93W TO 06N119W TO 02N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 90 NM N OF THE AXIS BETWEEN 93W AND 100W...WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 107W AND 125W...AND WITHIN 150 NM N AND 90 NM S OF THE AXIS W OF 135W. ...DISCUSSION... GULF OF TEHUANTEPEC...THE 1856 UTC OSCAT PASS SHOWED WINDS HAVE DIMINISHED TO A MODERATE NORTHERLY BREEZE IN THE GULF OF TEHUANTEPEC. NE SWELL FROM THE EARLIER GALE WILL CONTINUE TO KEEP SEAS OVER 8 FT SW OF THE GULF OF TEHUANTEPEC INTO 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. GULF OF CALIFORNIA...A COLD FRONT WILL PASS THROUGH THE GULF OF CALIFORNIA N OF 29N MON EVENING. SOUTHERLY WINDS WILL INCREASE TO A FRESH TO STRONG BREEZE AHEAD OF THE FRONT MON AFTERNOON AND SHIFT WESTERLY BEHIND THE FRONT MON EVENING. WINDS WILL DIMINISH OVERNIGHT MON NIGHT AS THE FRONT RACES EASTWARD. DIFFLUENCE ALOFT BETWEEN A WEAK RIDGE AXIS S OF 10N ALONG 116W AND A NEGATIVELY TILTED TROUGH FROM 13N110W TO 00N93W IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH/ITCZ AXIS. THIS CONVECTION IS 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 21N140W AND WEAK EASTERLIES PREVAIL TO ITS N. THIS LOW IS EMBEDDED IN DRY AIR ALOFT. MID- TO UPPER-LEVEL TROPICAL MOISTURE IS CONFINED S OF THE LOW PRIMARILY WITHIN 210 NM OF THE 60 KT JET AXIS FROM 13N140W TO CABO CORRIENTES MEXICO. THIS MOISTURE IS MANIFESTED AS CIRRUS. LOOKING AHEAD...A DEEP-LAYER TROUGH WILL MOVE INTO THE WESTERN UNITED STATES ON MON. THE 1028 MB SUBTROPICAL SURFACE HIGH LIES NEAR 29N142W AND EXTENDS A RIDGE E TO 29N125W THEN SOUTHEASTWARD TO 20N111W. THE PRESSURE GRADIENT BETWEEN THE SUBTROPICAL RIDGE AND THE ITCZ IS FORCING FRESH TO STRONG NE TRADE WINDS FROM 08N TO 20N W OF 130W AS SEEN BY THE 2034 UTC OSCAT 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 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 FORCING FRESH TO STRONG WINDS N OF 27N ALONG THE COAST OF THE BAJA CALIFORNIA PENINSULA AS SEEN BY THE 2030 UTC OSCAT PASS. SHIP DGBE ALSO OBSERVED 25 KT NW WINDS NEAR 29.5N116.5W AT 0000 UTC. FRESH TO STRONG NW WINDS WILL EXPAND AS FAR AS 300-360 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...SENDING A COLD FRONT THROUGH FAR NE WATERS LATE MON. A GALE WARNING IN IN EFFECT JUST N OF THE FORECAST AREA ON MON BEHIND THE FRONT. NW SWELL WILL COMBINE WITH NW WIND WAVES IN PACIFIC WATERS OFF THE BAJA CALIFORNIA PENINSULA...WITH SEAS EXPECTED TO REACH 14 FT BY MON EVENING. 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 BY SUN EVENING. SEAS ASSOCIATED WITH THIS SWELL TRAIN ARE CURRENTLY AS HIGH AS 11 FT OVER NW WATERS. THEY ARE EXPECTED TO SUBSIDE BELOW 8 FT THERE BY SUN NIGHT. $$ SCHAUER