000 AXPZ20 KNHC 170958 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT NOV 17 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 ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N74W TO LOW PRES OVER SW CARIBBEAN NEAR 10.5N80.5W 1011 MB TO 05.5N104W WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 09N125W TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM OF ITCZ BETWEEN 120W AND 129W. NO SIGNIFICANT CONVECTION ELSEWHERE. ...DISCUSSION... ALOFT...A TROUGH/RIDGE/TROUGH PATTERN CONTINUES THIS MORNING ACROSS THE DISCUSSION AREA. A BROAD AND ENERGETIC UPPER-LEVEL TROUGH COVERS MUCH OF THE N WATERS WHILE ANTICYCLONIC FLOW DOMINATES MOST OF THE REGION S OF 25N BETWEEN 92W AND 120WW OF 100W. THE RIDGE EXTENDS FROM A WEAKENING UPPER ANTICYCLONE NEAR 14N110W N-NE FROM 15N108W ACROSS BAJA CALIFORNIA AND NW MEXICO INTO THE SW CONUS...AND TO THE E NEAR 16N96W. BROAD UPPER TROUGH DOMINATES THE ENTIRE NE PACIFIC N OF 24N BETWEEN 120W AND 155W. STRONG W TO SW WINDS ARE NOTED THROUGH THE BASE OF THE TROUGH ALONG ABOUT 20N AND THEN OVER THE RIDGE...WITH A WIND MAXIMA TO 135 KT DEPICTED RECENTLY BY CIMSS ANALYSIS FROM 21N128W THROUGH 28N120W. THESE WINDS ARE TRANSPORTING ABUNDANT MID/UPPER LEVEL MOISTURE ACROSS THE FORECAST REGION FROM THE HAWAIIAN ISLANDS TO BAJA CALIFORNIA AND NW MEXICO. SATELLITE IMAGERY SHOWS A WIDE BAND OF TRANSVERSE HIGH CLOUDS IN ASSOCIATION WITH THESE STRONG WINDS. BROAD UPPER TROUGH ACROSS MOST OF THE EASTERN UNITED STATES...THE GULF OF MEXICO...AND THE NW CARIBBEAN ENTERS THE EASTERN PACIFIC WATERS THROUGH CENTRAL AMERICA NEAR 12N87W...THEN EXTENDS A TUTT W-SW TO A WEAKENING CYCLONIC VORTEX NEAR 06N111W...WHERE BROAD CYCLONIC FLOW EXTENDS SW ACROSS THE EQUATOR AT 112W. CONVERGENCE ALONG THE N SIDE OF THIS TUTT IS INHIBITING CONVECTION ALONG THE MONSOON TROUGH BETWEEN 85W AND 103W. AT THE SURFACE...A WEAKENING 1019 MB HIGH PRESSURE IS CENTERED NEAR 25N120W...AND IS EXPECTED TO COLLAPSE DURING THE NEXT 12-18 HOURS AS A COLD FRONT TO THE NW FROM 30N124W TO 25N133W SWEEPS NORTHEASTWARD OVER THE RIDGE AND SLOWLY DISSIPATES. THE FRONT CURRENTLY EXTENDS FROM A PARENT 1007 MB LOW OFF THE COAST OF CENTRAL CALIFORNIA THAT IS MOVING NE. WINDS HAVE DIMINISHING TO 20 KT OR LESS ON EITHER SIDE OF THE COLD FRONT...AND ALONG THE W COAST OF BAJA CALIFORNIA. HOWEVER...A 0640 OCEANSAT PASS SHOWED NW WINDS AROUND 20 KT LINGERING THROUGH CENTRAL PORTIONS OF THE GULF OF CALIFORNIA... WHERE SEAS REMAIN NEAR 6 FT. AS THE FRONT CONTINUES TO SHIFT E AND NE...HIGH PRESSURE WILL BUILD BACK ACROSS THE N PART OF THE AREA BY SUN...AND ACT TO FRESHEN THE TRADE WINDS TO 20-25 KT S OF 19N AND W OF 125W. LONG PERIOD NW SWELL ASSOCIATED WITH THE LOW PRESSURE SYSTEM IS PUSHING ACROSS THE NW PART OF THE REGION BEHIND THE FRONT... WITH COMBINED SEAS 8 TO 11 FT. THIS PULSE OF NW SWELLS WILL PROPAGATE S AND E ACROSS THE REGIONAL WATERS OVER THE WEEKEND... WITH SEAS SUBSIDING TO 8-9 FT EARLY SUN MORNING...WITH A NEXT PULSE OF LARGE NW SWELL ENTERING THE NW WATERS SUN...WITH SEAS BUILDING TO 10-12 FT ACROSS NW PORTIONS BY SUNDAY AFTERNOON AND EVENING. GAP WINDS... A GALE WARNING REMAINS IN EFFECT ACROSS THE GULF OF TEHUANTEPEC THIS MORNING. PERSISTENT NORTHERLY WINDS 20-30 KT CONTINUE TO BE ENHANCED BY NOCTURNAL DRAINAGE FLOW ACROSS THE AREA...REACHING MINIMAL GALE FORCE ROUGHLY BETWEEN 0600 AND 1200 UTC. THIS GAP WIND FLOW IS EXPECTED TO PERSIST FOR SEVERAL MORE DAYS...WITH NOCTURNAL PULSING TO AROUND 30 KT EXPECTED SATURDAY NIGHT...AND THEN LIKELY AGAIN TO GALE FORCE SUNDAY NIGHT. THE PRESENT GALE WARNING IS THEREFORE EXPECTED TO BE DISCONTINUED LATER THIS MORNING...AND WILL LIKELY BE REISSUED SUN NIGHT AS NORTHERLY FLOW BEGINS TO INCREASE AGAIN ACROSS THE SW GULF OF MEXICO. PULSING OF NOCTURNAL WINDS ARE ALSO EXPECTED ACROSS THE GULF OF PAPAGAYO DURING THE NEXT FEW DAYS...REACHING AROUND 20 KT FROM 0600 TO 1200 UTC...WITH SEAS OF 6-7 FT THROUGH AND DOWNWIND OF THE GULF. $$ STRIPLING