000 AXPZ20 KNHC 201448 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT OCT 20 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1430 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH 12N87W TO 11N110W TO 10N120W TO 12N127W TO 09N140W. SCATTERED MODERATE TO STRONG N OF 09N TO MONSOON TROUGH AXIS BETWEEN 89W AND 99W. SCATTERED MODERATE WITHIN 120 NM EITHER SIDE OF TROUGH AXIS BETWEEN 110W AND 114W...AND BETWEEN 128W AND 132W. ...DISCUSSION... AN UPPER LEVEL ANTICYCLONE IS CENTERED WELL OF THE AREA NEAR 27N155W WITH AN UNSTABLE UPPER RIDGE EXTENDING EAST ALONG 31N TO THE W-CENTRAL CALIFORNIA COAST WHICH IS COLLAPSING TO THE SE OVER THE EXTREME NW PORTION OF THE DISCUSSION AREA. TWO LARGE UPPER CYCLONES DOMINATE THE SUBTROPICS W OF 118W WITH CENTERS NEAR 29N123W AND 21N145W. SOME UPPER LEVEL MOISTURE IS OBSERVED OVER THE N SEMICIRCLE OF THE EASTERN CYCLONE...AND IS SPREADING NE ACROSS THE EXTREME NW PORTION OF THE BAJA PENINSULA THIS MORNING. OTHERWISE THE UPPER LEVELS APPEAR VERY DRY N OF 16N W OF 117W AND SUPPRESSING CONVECTION. AN UPPER CYCLONE IS OVER THE DEEP TROPICS NEAR 02N130W SETTING UP AN AREA OF WEAK UPPER DIFFLUENCE OVER THE WESTERN SEGMENT OF THE MONSOON TROUGH AND ITCZ...AND SUPPORTING THE CONVECTION PREVIOUSLY DESCRIBED TO THE W OF 128W. SOME OF THE DEBRIS MOISTURE IS ADVECTED NE TO 15N BETWEEN 127W-137W...AND MAY ORGANIZE INTO A TROPICAL PLUME IS THE INCREASING SOUTHERLY FLOW SE OF THE UPPER CYCLONES. THE EASTERN PORTION OF THE DISCUSSION IS DOMINATED BY A QUASI-STATIONARY UPPER ANTICYCLONE OVER W-CENTRAL OLD MEXICO AT 20N104W WITH A RIDGE EXTENDING NNW TO A CREST OVER EASTERN ARIZONA. UPPER MOISTURE CONTINUES TO STREAM E ACROSS THE CENTRAL BAJA PENINSULA...AND ACROSS THE RIDGE OVER NORTHERN MEXICO TO OVER W TEXAS. THE ENVELOPE OF ANTICYCLONIC FLOW EXTENDS S OVER THE DISCUSSION AREA N OF 07N TO THE E OF 112W. THE UPPER EASTERLY FLOW IS ADVECTING DEBRIS MOISTURE FROM THE MONSOON TROUGH CONVECTION PREVIOUSLY MENTIONED WESTWARD BETWEEN 07N-13N FROM CENTRAL AMERICA TO 103W. A BROAD SURFACE RIDGE COVERS THE SUBTROPICS W OF A LOW LEVEL TROUGH EXTENDING FROM 26N122W TO 19N129W. NORTHERLY 20 KT WINDS ARE CURRENTLY OBSERVED TO THE W OF A LINE FROM 30N132W TO 24N140W...WITH SEAS TO 9 FT PRIMARILY DUE TO MIXING NE AND NW SWELL. THIS AREA OF ENHANCED N WINDS WILL GRADUALLY DIMINISH TO 15 KT TONIGHT WITH SEAS SUBSIDING TO 6-7 FT. EXPECT THE LOW LEVEL TROUGH TO FILL TODAY AS THE SURFACE RIDGE BUILDS E ACROSS THE ENTIRE AREA N OF 17N W OF 108W BY LATE SUN. SEAS OF 3-5 FT IN NW SWELL ARE EXPECTED ALONG THE ENTIRE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA THROUGH LATE TUE...THEN GUIDANCE SUGGESTS NW WINDS WILL INCREASE TO 15-20 KT WITH SEAS BUILDING 5-7 FT ALONG THE W SHORE OF PENINSULA ON TUE NIGHT. SEAS OF 1-3 FT EXPECTED ACROSS THE ENTIRE GULF OF CALIFORNIA THROUGH LATE MON. GUIDANCE INDICATING NW WINDS WILL INCREASE TO 15-20 KT...SEAS BUILDING TO 3-4 FT...OVER THE GULF WATERS TO THE S OF 24.5N BEGINNING MON NIGHT. GAP WINDS...NORTHERLY SURGE OF 20-25 KT WINDS CONTINUES IN THE GULF OF TEHUANTEPEC AND IS EXPECTED TO PULSE THROUGH SUN WITH THE STRONGEST DRAINAGE FLOW OCCURRING LATE EACH NIGHT TILL JUST AFTER SUNRISE EACH MORNING. THE GFS GUIDANCE CONTINUES TO SUGGEST THIS NORTHERLY FLOW WILL HELP TRIGGER LOW PRESSURE DEVELOPMENT WITHIN THE MONSOON TROUGH NEAR 11N98W ON WED. ALTHOUGH THERE IS A HINT OF THE LOW PRESSURE DEVELOPMENT ALONG THE MONSOON TROUGH AXIS IN OTHER NWP GUIDANCE...THE GFS IS MUCH MORE AGGRESSIVE AND THUS ITS SOLUTION IS TONED DOWN CONSIDERABLY IN THE EXPERIMENTAL GRIDDED FIELDS. $$ COBB