000 AXPZ20 KNHC 060315 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT OCT 06 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...SPECIAL FEATURE... EMBEDDED SURFACE LOW PRESSURE CONTINUES WITHIN THE THE MONSOON TROUGH AT 13.5N116.5W AND IS ESTIMATED AT 1008 MB...MOVING W OR 275 DEG AT 13 KT. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 240 NM OVER THE NW QUADRANT...AND FROM 150 TO 300 NM OUT OVER THE NE QUADRANT. THE CONVECTION OVER THE NW QUADRANT HAS INTERMITTENT BANDING FEATURES WHILE LIGHTNING DATA SUGGESTS THE HEAVIEST ACTIVITY IS NOW NE OF THE CENTER. THE LOW IS MOVING W UNDER A LARGE RIDGE WITH FAVORABLE UPPER LEVEL DIFFLUENCE EXPECTED FOR A COUPLE OF DAYS...AND IMPRESSIVE UPPER LEVEL OUTFLOW IS CURRENTLY OBSERVED OVER ITS NORTHERN SEMICIRCLE. NE-E WINDS AT 20-30 KT ARE WITHIN 180 NM OVER THE NW SEMICIRCLE. EXPECT THE LOW TO MOVE W TO NEAR 14.5N120.5W 1007 MB LATE SAT AND NEAR 16N124W LATE SUN WITH THE POSSIBILITY OF TROPICAL CYCLONE FORMATION. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS W ACROSS THE SOUTHERN CARIBBEAN ALONG 11N FROM THE COLOMBIAN COAST TO NORTHERN COSTA RICA TO 10N85W ...THEN DIPS SW TO 09N94W THEN TURNING NW TO 16N109W...THEN SW AGAIN THROUGH THE EMBEDDED LOW AT 13.5N 116.5W. THE TROUGH AXIS CONTINUES SW FROM THE LOW TO 09N125W... TO 11N131W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES SW TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITH OCCASIONAL LIGHTNING IS ORGANIZED WITHIN 75 NM EITHER SIDE OF A LINE FROM 06N83W TO 08N92W...AND SE OF THE PREVIOUSLY MENTIONED LOW PRESSURE WITHIN 75 NM EITHER SIDE OF A LINE FROM 13.5N113W TO 07N118W. ISOLATED MODERATE AND STRONG CONVECTION IS NOTED IN THE AREA BOUNDED BY 07N-12.5N BETWEEN 92W AND 102W...AND WITHIN 30 NM OF 10N130W. ...DISCUSSION... AN UPPER LEVEL ANTICYCLONE IS POSITIONED NEAR 22N117W WITH UPPER RIDGES EXTENDING N BEYOND 32N116W...E TO A SHARP CREST AT 22N105W AND SW TO A CREST AT 16N140W. AN UPPER 50-90 KT JET IS DETECTED BY CLOUD MOTION VECTORS ALONG THE NW AND N PERIPHERY OF THE ANTICYCLONE ADVECTING A 540 NM WIDE PLUME OF UPPER MOISTURE FROM THE CENTRAL PACIFIC NE AND E ACROSS THE NORTHERN RIDGE CREST TURNING SE AND SPILLING ACROSS SOUTHERN CALIFORNIA... ARIZONA...NEW MEXICO AND RECENTLY OVER NORTHERN TEXAS WHERE IT BEGINS TO TURN CYCLONICALLY NE IN RESPONSE TO AN UPPER TROUGH OVER THE CENTRAL CONUS. UPPER DIFFLUENCE ALONG THE SOUTHERN PERIPHERY OF THIS LARGE RIDGE IS SUPPORTING THE CONVECTION ALONG THE MONSOON TROUGH...AND THE DEVELOPING EMBEDDED LOW WITHIN THE MONSOON TROUGH...ALL PREVIOUSLY DESCRIBED. THE DEBRIS MOISTURE IS FANNING OUT N TO ALONG 21N BETWEEN 109W-117W...AND ALSO FANNING OUT S REACHING ALONG 05N BETWEEN 112W-124W BEFORE EVAPORATING. OTHERWISE THE LARGE ANTICYCLONE IS SUPPRESSING CONVECTION ACROSS THE ENTIRE SUBTROPICAL PORTION OF THE DISCUSSION AREA. AS MENTIONED AN UPPER SHORTWAVE TROUGH OVER THE CENTRAL CONUS EXTENDS SW ACROSS THE WESTERN GULF OF MEXICO AND OVER CENTRAL MEXICO THROUGH A SMALL UPPER CYCLONE AT 20N97W...WITH THE TROUGH CONTINUING S ACROSS THE DEEP TROPICS WHERE IT BECOMES INVERTED INTO AN UPPER CYCLONE OVER THE EQUATOR AT 101W. THIS TROUGH EFFECTIVELY SEPARATES THE UPPER FLOW OVER THE TROPICAL PACIFIC. BROAD UPPER RIDGING IS NOTED E OF THIS UPPER TROUGH AND ENHANCING THE CONVECTION ALONG THE EASTERN SEGMENT OF THE LOWER LEVEL MONSOON TROUGH AS PREVIOUSLY DESCRIBED. SOME OF THE RESULTANT DEBRIS MOISTURE IS ADVECTED N ACROSS CENTRAL AMERICA E OF 87W...WITH THE MOISTURE TURNING E ACROSS THE ENTIRE SOUTHERN CARIBBEAN. SOME OF THE DEBRIS MOISTURE IS ALSO ADVECTED S TO ALONG THE EQUATOR BETWEEN 85W-90W AND MAY SOON REACH THE GALAPAGOS ISLANDS. ELSEWHERE AT THE LOW LEVELS...BROAD SURFACE RIDGING COVERS THE DISCUSSION AREA N OF 18N W OF 115W. SOUTHWESTERLY LOW LEVEL MONSOONAL WINDS AT 15-20 KT...ALONG WITH CROSS EQUATORIAL S SWELL...CONTINUES TO RESULT IN AN AREA OF SEAS 6-8 FT IN THE AREA BOUNDED BY 08N-10N BETWEEN 114W-120W. THIS AREA WILL SHIFT N TO ALONG 13N ON SAT...THEN WINDS WILL DIMINISH TO 15 KT AND SEAS WILL SUBSIDE TO 4-7 FT ON SUN. IN THE MEANTIME...NW WINDS NE OF THE SURFACE RIDGE WILL INCREASE TO 20-25 KT OVER THE AREA N OF 28N E OF 118W TO THE NORTHERN BAJA CALIFORNIA PENINSULA... WITH LITTLE CHANGE EXPECTED THROUGH EARLY TUE...THEN THE GRADIENT WILL RELAX SUPPORTING NW 10-15 KT AND SEAS 4-5 FT ALONG THE ENTIRE WESTERN COAST OF THE BAJA PENINSULA THROUGH MID WEEK. THEREAFTER...GUIDANCE SUGGESTS SEAS WILL INCREASE TO 6 FT IN BUILDING NW SWELL OVER THE AREA N OF 28N BY LATE NEXT WEEK. REFRACTIVE SWELL...RESULTING IN SEAS TO 3 FT...ARE EXPECTED OVER THE GULF OF CALIFORNIA S OF 24.5N THROUGH ALL OF NEXT WEEK. GAP WINDS...NORTHERLY WINDS AT 20-25 KT ARE EXPECTED TO PULSE ACROSS THE GULF OF TEHUANTEPEC THROUGH LATE TONIGHT THEN DIMINISH BY MIDDAY SAT...THEN PULSE AGAIN TO 20-25 KT STARTING LATE SUN NIGHT AND CONTINUING THROUGH THE MIDDLE OF NEXT WEEK... WITH THE STRONGEST DRAINAGE FLOW OCCURRING LATE EACH NIGHT THROUGH A COUPLE OF HOURS AFTER SUNRISE EACH MORNING. EXTENDED GUIDANCE SUGGESTS THE NORTHERLY FLOW WILL INCREASE TO 30 KT IN THE GULF OF TEHUANTEPEC ON THU MORNING. $$ NELSON