000 AXPZ20 KNHC 302129 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN OCT 30 2011 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 2000 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH WAS ANALYZED FROM 10N85W TO 06N94W TO 06N100W. THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 06N100W TO 10N122W TO 08N130W TO 09N140W. SCATTERED MODERATE CONVECTION WAS ALONG THE E END OF THE MONSOON TROUGH FROM 04N TO 10N E OF 90W. ...DISCUSSION... AN UPPER LEVEL LOW LIES W OF THE FORECAST AREA AND E OF THE BIG ISLAND OF HAWAII. THIS LOW IS ON THE WESTERN EDGE OF A BROAD UPPER TROUGH THAT EXTENDS NE OVER THE NORTHERN PORTION OF THE FORECAST AREA. TROPICAL MOISTURE ALOFT IS BEING ADVECTED INTO THE LEADING EDGE OF THIS UPPER TROUGH AND IS MANIFESTED AS CIRRUS OVER THE FAR W PORTION OF THE FORECAST AREA BETWEEN 15N AND 25N. TO THE SE...AN UPPER RIDGE AXIS ALONG 134W S OF 25N. DIFFLUENCE ASSOCIATED WITH THIS RIDGING IS ENHANCING THE SCATTERED MODERATE CONVECTION FOUND FROM 13N TO 15N BETWEEN 130W AND 133W. THE 1029 MB SUBTROPICAL HIGH LIES NEAR 35N138W AND EXTENDS A RIDGE AXIS SE TO 20N130W. THE PRES GRADIENT BETWEEN THE RIDGE AND THE ITCZ IS STRONG ENOUGH TO YIELD FRESH TRADE WINDS OVER MUCH OF THE AREA W OF 127W BETWEEN 12N AND 21N ACCORDING TO THE 1838 UTC ASCAT PASS. THE SUBTROPICAL HIGH IS EXPECTED TO MERGE WITH A STRONGER HIGH TO ITS NW MON AS THE COLD FRONT CURRENTLY BETWEEN THESE TWO HIGH CENTERS DISSIPATES N OF THE AREA. THIS WILL SHIFT THE AREA OF FRESH TRADE WINDS SLIGHTLY FARTHER W BY TUE. IN ADDITION...THE COLD FRONT WILL DIG SOUTH THROUGH THE WESTERN U.S. MON INTO TUE AND INCREASE THE PRES GRADIENT OVER N WATERS BETWEEN IT AND HIGH PRES TO ITS W. FRESH NE WINDS ARE EXPECTED OVER NW WATERS ON MON AND TUE AS A RESULT...WITH SEAS EXPECTED TO REACH 11 FT IN NW SWELL. WHILE THE 1518 UTC ASCAT PASS FAILED TO SHOW FRESH SW WINDS CONTINUING IN THE AREA S OF PANAMA...SHIP A8MG8 REPORTED 20 KT SW WINDS NEAR 06N80W AT 1500 UTC. WINDS HERE ARE DRIVEN BY THE PRES GRADIENT BETWEEN TROUGHING OVER THE WESTERN CARIBBEAN AND RIDGING S OF THE EQUATOR IN THE EASTERN PACIFIC. THE TROUGHING IN THE CARIBBEAN HAS WEAKENED SOME OVER THE PAST 24 HOURS... SHRINKING THE AREA OF FRESH WINDS S OF PANAMA. ANY FRESH SW FLOW HERE IS EXPECTED TO DIMINISH OVERNIGHT TONIGHT. SCATTERED MODERATE CONVECTION FOUND OVER MUCH OF THE AREA OFFSHORE OF COLOMBIA...PANAMA...AND COSTA RICA IS DESCRIBED IN THE SECTION ABOVE AND THAT CONVECTION EXTENDS INLAND OVER PANAMA...COSTA RICA...AND SOUTHERN NICARAGUA. THIS CONVECTION LIES UNDER UPPER LEVEL DIFFLUENCE ASSOCIATED WITH A RIDGE AXIS ALOFT THAT EXTENDS FROM EASTERN CUBA THROUGH THE WESTERN CARIBBEAN INTO NICARAGUA AND WITHIN THE REGION OF HIGHEST PRECIPITABLE WATER VALUES IN THE FORECAST AREA. WIDESPREAD PRECIPITATION SHOULD CONTINUE IN THIS AREA THROUGH TUE. GAP WINDS...THERE HAS NOT BEEN A SCATTEROMETER PASS OVER THE GULF OF TEHUANTEPEC WITHIN THE LAST 24 HOURS AND THERE WERE VERY FEW SHIP REPORTS IN THE AREA. THE FORECAST MODELS SHOW WINDS HOVERING AROUND GALE FORCE THIS EVENING BEFORE A NORTHERN STREAM REINFORCING TROUGH SWEEPS THROUGH THE GULF OF MEXICO AND BRINGS WINDS SOLIDLY BACK INTO THE GALE RANGE OVERNIGHT. NIGHTTIME DRAINAGE FLOW FROM THE MOUNTAINS WILL ALSO HELP KEEP WINDS AT GALE FORE. THE GALE WARNING WILL CONTINUE TO BE IN EFFECT THROUGH THE END OF THE FORECAST PERIOD TUE EVENING...WITH THE GALE CURRENTLY EXPECTED TO END AROUND SUNSET TUE. $$ SCHAUER