000 AXPZ20 KNHC 041551 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI DEC 04 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1515 UTC. ...ITCZ... AXIS ANALYZED ALONG 05N78W TO 07N105W TO 07N116W TO 11N124W TO 06N140W. NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION WAS NOTED WITHIN 90 NM N OF THE AXIS E OF 82W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WAS NOTED WITHIN 120 NM N OF THE AXIS BETWEEN 102W AND 105W AND WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 117W AND 121W AND WITHIN 120 NM N OF THE AXIS BETWEEN 127W AND 132W. ...DISCUSSION... AN AMPLIFIED UPPER PATTERN REMAINS IN PLACE OVER THE FORECAST AREA N OF 20N...WITH AN UPPER LOW SPINNING NEAR 22N135W... EXPECTED TO PASS TO THE E THROUGH AN UPPER LEVEL RIDGE AXIS EXTENDING FROM N OF OUR AREA OFF THE U.S. CALIFORNIA COAST TO 30N122W TO 22N119W. THIS FEATURE WILL THEN MOVE INTO THE SW EDGE OF A BROAD UPPER LEVEL TROUGH IN PLACE OVER CENTRAL NORTH AMERICA BY 48 HOURS. THE PASSAGE OF THIS LOW THROUGH THE UPPER RIDGE WILL WEAKEN THE SURFACE RIDGING OVER THE W WATERS... REDUCING THE EASTERLY TRADE WINDS TO 20 KT OVER A SMALL PORTION OF THE AREA (FROM 10N TO 20N BETWEEN 115W AND 125W) TODAY...WITH TRADES FURTHER DIMINISHING TO LESS THAN 20 KT ALL AREAS BY 24 HOURS. TO THE W OF THE UPPER RIDGE AXIS (CENTERED OVER THE CENTRAL N PACIFIC) LIES ANOTHER MEAN UPPER TROUGH EXTENDING FROM NEAR 40N155W TO 13N160W. A SERIES OF MID TO UPPER LEVEL SHORTWAVE TROUGHS WILL MOVE NORTHEASTWARD ALONG THE LEADING EDGE OF THIS BROAD TROUGH OVER THE NEXT FEW DAYS. THE FIRST IS CURRENTLY DISSIPATING JUST NW OF THE FORECAST AREA AND HAS BROUGHT NW SWELL IN THE 8 TO 11 FT RANGE TO THE NW WATERS WHILE A SECOND IS EXPECTED TO DRAG ITS ASSOCIATED COLD FRONT JUST TO THE NW OF THE WATERS BY 36 HOURS...WHERE IT WILL EVENTUALLY DISSIPATE. THE CURRENT SET OF NW SWELL WILL DECAY AS IT CONTINUES TO PROPAGATE SOUTHWARD TOWARD THE EQUATOR...WHILE A NEW SET OF NW SWELL WILL BUILD SEAS BACK INTO THE 8 TO 12 FT RANGE OVER NW WATERS (NEAR THE WEAKENING FRONTAL BOUNDARY) AT THE END OF THE PERIOD/END OF THE WEEKEND. S OF 20N...TWO SURFACE LOW PRES SYSTEMS AND A SURFACE TROUGH ARE EMBEDDED WITHIN THE ITCZ. THE SURFACE TROUGH FROM 15N123W TO 06N125W REMAINS THE MOST CONNECTIVELY ACTIVE...WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION FOUND WITHIN 180 NM EITHER SIDE OF THE TROUGH AXIS. THIS TROUGH LIES IN AN AREA OF UPPER LEVEL DIFFLUENCE BETWEEN AN ANTICYCLONE CENTERED NEAR 12N114W AND A 40 TO 60 KT SOUTHWESTERLY UPPER JET TO ITS NW EXTENDING FROM 11N140W TO 23N124W. A WEAK 1010 MB SURFACE LOW CAN BE FOUND IN CONJUNCTION WITH THE RIGHT REAR QUADRANT OF THIS UPPER JET NEAR 07N135W. CONVECTION ASSOCIATED WITH THIS LOW HAS DIMINISHED AS SW SHEAR ALOFT INCREASED. ANOTHER 1010 MB SURFACE LOW IS CENTERED NEAR 08N111W. CONVECTION ASSOCIATED WITH THIS LOW HAS ALSO DIMINISHED EARLY THIS MORNING. THE LOW IS UNDER AN UPPER RIDGE AXIS STEMMING FROM AN ANTICYCLONE CENTERED NEAR 10N88W AND EXTENDING W TO 07N100W AND TO 17N122W. THIS UPPER RIDGE WILL CONTRACT TO THE E AS THE TROUGHING ASSOCIATED WITH THE UPPER LOW OVER THE N WATERS PASSES E TOWARD THE ANTICYCLONE. IN ADDITION...NORTHERLY WINDS ON THE WESTERN SIDE OF THE ANTICYCLONE ARE EXPECTED TO INCREASE DURING THE NEXT FEW DAYS WHICH WILL LIMIT CONVECTION OVER THE FAR E WATERS. HOWEVER CURRENTLY NUMEROUS MODERATE SCATTERED STRONG CONVECTION CAN BE FOUND WITHIN 90 NM N OF THE ITCZ E OF 82W...MAINLY BEING ENHANCED BY OFFSHORE/NORTHERLY FLOW OFF THE ISTHMUS OF PANAMA AND CONVERGENCE ALONG THE ITCZ. 1033 MB HIGH PRES OVER THE U.S. ROCKY MOUNTAINS WILL SETTLE SOUTH TO THE RIO GRANDE VALLEY TODAY AND THEN PUSH RAPIDLY EASTWARD OVER THE WEEKEND. THE PRESSURE GRADIENT BETWEEN THIS HIGH...TROUGHING IN THE VICINITY OF THE GULF OF CALIFORNIA...AND A RIDGE TO THE W OF THE BAJA PENINSULA HAS STRENGTHENED THE NW TO N WINDS IN THE N GULF OF CALIFORNIA TO THE 20 TO 25 KT RANGE ACCORDING TO AN EARLIER ASCAT PASS. THESE WINDS ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT BY EARLY SAT AFTERNOON AS THE HIGH PRESSURE SYSTEM MOVES AWAY...WEAKENING THE PRES GRADIENT. GAP WINDS... NORTHERLY WINDS IN THE 20 TO 30 KT RANGE CONTINUE TO FUNNEL THROUGH THE GULF OF TEHUANTEPEC AND DOWNSTREAM WATERS WITH NORTHERLY FLOW IN PLACE N OF THE ISTHMUS OF TEHUANTEPEC BEHIND A COLD FRONT THAT PREVIOUSLY MOVED THROUGH THE GULF OF MEXICO WATERS. WINDS WILL REACH GALE FORCE WITHIN 24 HOURS AS A STRONGER COLD FRONT MOVES THROUGH THE S GULF OF MEXICO TONIGHT. WINDS WILL THEN DIMINISH TO BELOW GALE FORCE BY LATE SAT NIGHT AS WINDS IN THE S GULF OF MEXICO VEER TO THE E-SE. EASTERLY TRADES IN THE SW CARIBBEAN SEA WILL CONTINUE TO FUNNEL THROUGH THE GULF OF PAPAGAYO AND DOWNSTREAM TO NEAR 89W DURING THE NEXT FEW DAYS. THE WINDS WILL BE STRONGEST IN THE MORNING HOURS WITH THE AID OF DRAINAGE FLOW. $$ LEWITSKY