000 AXPZ20 KNHC 010919 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN APR 01 2012 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0700 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 04N127W TO 04N140W. NO SIGNIFICANT CONVECTION NOTED NEAR THE ITCZ AXIS. ...DISCUSSION... A WEAKENING COLD FRONT LIES FROM 32N117W TO 24N126W AND THEN IS DISSIPATING TO 22N139W. THE 0446 AND 0626 UTC ASCAT PASSES SHOW A LARGE AREA OF FRESH TO STRONG N WINDS BEHIND THE FRONT. SUBTROPICAL RIDGING IS BUILDING OVER THE AREA...STEMMING FROM A 1032 MB HIGH PRES SYSTEM NEAR 32N141W. THE PRES GRADIENT BETWEEN THIS RIDGING AND THE ITCZ TO ITS S IS GENERATING A WIDE SWATH OF FRESH TO STRONG TRADE WINDS FROM 06N TO 20N W OF 125W. THESE CONDITIONS WERE OBSERVED BY THE 0624 UTC ASCAT PASS AND SHIP PDGS WHO REPORTED NE WINDS AT 25 KT NEAR 18N125W AT 0600 UTC. WINDS ARE ALSO BEGINNING TO PICK UP ALONG THE W COAST OF BAJA CALIFORNIA WHERE THE PRES GRADIENT IS INCREASING BETWEEN TROUGHING OVER CENTRAL MEXICO AND THE BUILDING SUBTROPICAL RIDGE. FRESH NW WINDS WERE OBSERVED IN THIS AREA BY SHIP 3FPR9 NEAR 25N113W AT 0500 UTC. THE FRONT WILL CONTINUE TO WEAKEN AS IT MOVES THROUGH BAJA CALIFORNIA SUNDAY...DISSIPATING AS IT MOVES INLAND ON MON. THE SUBTROPICAL HIGH WILL BE FORCED EASTWARD OVER THE NEXT FEW DAYS AS A RAPIDLY STRENGTHENING COLD FRONT ENCROACHES UPON IT FROM THE NW. TRADES AND WINDS BEHIND THE COLD FRONT WILL REMAIN FRESH TO STRONG OVER A LARGE AREA THROUGH EARLY MONDAY...BUT WILL RAPIDLY DIMINISH BY EARLY TUESDAY AS THE HIGH WEAKENS OVER N WATERS NEAR 130W. WHILE THE WINDS ARE STRONG BEHIND THE COLD FRONT...THE BIGGER STORY IS THE LARGE NW SWELL TO 23 FEET USHERED INTO THE AREA BY THE FRONT. SEAS OVER 20 FT WILL BE CONFINED N OF 27N. THE SWELL WILL SPREAD SOUTHEASTWARD THROUGH THE FORECAST AREA. MAXIMUM SEAS WILL BE SLOW TO SUBSIDE UNTIL WINDS BEGIN TO DIMINISH MIDDAY MONDAY. THE UPPER TROUGH SUPPORTING THE COLD FRONT OVER N WATERS IS TURNING SLIGHTLY NEGATIVE TILT AS IT MOVES INTO THE WESTERN U.S. THIS AMPLIFIED TROUGH IS EXPECTED TO CUT OFF FROM THE NORTHERN STREAM BY EARLY MON...LEAVING BEHIND A LOW OVER THE U.S. FOUR CORNERS STATES THROUGH EARLY TUE. CURRENTLY...A STRONG ANTICYCLONE LIES OVER EASTERN COLORADO AND WILL BE FORCED EASTWARD BY THE APPROACHING TROUGH INTO THE MID MISSISSIPPI VALLEY MONDAY BEFORE DISSIPATING BY EARLY TUE. THIS ANTICYCLONE IS WEAKENING THE POSITIVELY TILTED UPPER TROUGH THAT EXTENDS THROUGH THE SOUTHERN GULF OF CALIFORNIA TO 22N130 THEN SOUTHWESTWARD TO A STRONG UPPER LOW THAT LIES NEAR 17N137W. THE WESTERN PORTION OF THIS TROUGHING...INCLUDING THE LOW...IS BEGINNING TO PHASE WITH THE UPPER TROUGH SUPPORTING THE COLD FRONT OVER N WATERS. THIS STRONG UPPER LOW OVER THE TRADE WIND REGION WILL BE PULLED EAST-NORTHWARD BY THIS PHASING TO NEAR 20N125W BY EARLY TUE. THE PRIMARY IMPACT OF THIS UPPER LOW IS AN INCREASE IN SHOWERS AND MULTILAYERED CLOUDINESS OVER W CENTRAL WATERS. 60-80 KT SW WINDS ALOFT ON THE SE SIDE OF THE UPPER LOW ARE TRANSPORTING MID TO UPPER LEVEL MOISTURE...MANIFESTED PRIMARILY AS CIRRUS CLOUDS...OVER THE REGION FROM 04N TO 17N W OF 120W. THIS FEATURE SHOULD CONTINUE TO INITIATE SOME CONVECTION EAST OF THE TROUGH AXIS THROUGH MON...WITH THE CONVECTIVELY ACTIVE AREA SHRINKING DURING THAT TIME AS THE ATMOSPHERE BECOMES MORE STABLE NEAR THE WEAKENING LOW. LIGHT TO MODERATE WINDS OTHERWISE PREVAIL E OF 110W. A SURFACE TROUGH LIES S OF THE GULF OF PAPAGAYO FROM 08N85W TO 04N92W TO 05N97W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION LIES WITHIN 150 NM NW AND 210 NM SE OF THE TROUGH BETWEEN 86W AND 92W. CONVECTION HERE COINCIDES WITH THE PORTION OF THE FORECAST AREA WITH THE HIGHEST PRECIPITABLE WATERS VALUES AND IS BEING ENHANCED BY DIFFLUENCE ALOFT BETWEEN 45-55 KT W FLOW TO THE N AND 15 TO 20 KT NW WINDS TO THE S. GAP WINDS... GULF OF CALIFORNIA...THE PRES GRADIENT THAT IS INCREASING WINDS OFF THE W COAST OF BAJA CALIFORNIA SHOULD SHIFT EASTWARD A BIT TODAY. FRESH N WINDS ARE EXPECTED TO DEVELOP IN THE GULF OF CALIFORNIA N OF 30N THIS MORNING. ONCE THE COLD FRONT ENTERS THE GULF SUNDAY...WINDS WILL GRADUALLY INCREASE TO STRONG OUT OF THE NW BEHIND THE COLD FRONT. THESE WINDS WILL BEGIN TO DIMINISH BEFORE TUE MORNING AS THE COLD FRONT DISSIPATES AND THE SUBTROPICAL HIGH WEAKENS. $$ SCHAUER