000 AXPZ20 KNHC 052155 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC FRI OCT 05 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURE... SURFACE LOW PRESSURE HAS DEVELOPED WITHIN THE THE MONSOON TROUGH AT 13N113.5W AND IS ESTIMATED AT 1008 MB. THIS IS ABOUT 700 MILES SOUTH-SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA WITH THE LOW MOVING W OR 270 DEG AT 16 KT. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 270 NM OVER THE W AND WITHIN 120 NM OVER THE E SEMICIRCLES OF THE CENTER. THE CONVECTION OVER THE NW QUADRANT APPEARS TO BE ORGANIZING ALONG A BAND. THE LOW IS MOVING W UNDER A LARGE RIDGE WITH FAVORABLE UPPER LEVEL DIFFLUENCE EXPECTED FOR A COUPLE OF DAYS. CURRENTLY NE-E WINDS AT 20-30 KT IS OBSERVED ON SCATTEROMETER DATA WITHIN 240 NM N OF CENTER...AND 20-25 KT ELSEWHERE WITHIN 180 NM OVER THE NW SEMICIRCLE. EXPECT THE LOW TO MOVE W TO NEAR 14N119W 1006 MB ON SAT AFTERNOON WITH THE AREA OF 20-25 KT WINDS EXPECTED WITHIN 240 NM OVER THE NW SEMICIRCLE...WITH SEAS BUILDING TO 10 FT. EXPECT THE LOW PRES TO MOVE TO NEAR 15N123W LATE SUN WITH WINDS AT 20-30 KT WITHIN 300 NM NW AND 60 NM SE SEMICIRCLES OF CENTER WITH SEAS OF 8 TO 12 FT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS NW ACROSS THE SOUTHERN CARIBBEAN FROM THE COLOMBIAN COAST AT 08N77W ACROSS EASTERN PANAMA TURNING W ACROSS NORTHERN COSTA RICA TO 10N85W...THEN DIPS SW TO 07N98W THEN TURNING NW TO A 1009 MB SURFACE LOW EMBEDDED WITHIN THE MONSOON TROF. THE TROUGH AXIS CONTINUES SW FROM THE LOW TO 09N121W...TURNING SLIGHTLY NW THROUGH ANOTHER EMBEDDED LOW PRES AT 11N129W...THEN SW TO 07N137W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES SW TO BEYOND 06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITH FREQUENT LIGHTNING IS ORGANIZED WITHIN 90 NM EITHER SIDE OF A LINE FROM 05N81W TO 09N87W. ISOLATED MODERATE AND STRONG CONVECTION IS NOTED IN THE AREA BOUNDED BY 06N TO 12N BETWEEN 90W AND 101W... AND ALSO WITHIN 120 NM EITHER SIDE OF A LINE FROM 14N106W TO 07N116W TO 08N123W TO 11N129W TO 08N134W. ...DISCUSSION... A BROAD UPPER LEVEL CYCLONE IS STATIONARY N OF THE DISCUSSION AREA NEAR 36N134W. AN UPPER LEVEL ANTICYCLONE IS POSITIONED NEAR 22N116W WITH UPPER RIDGES EXTENDING N BEYOND 32N117W...E TO A SHARP CREST AT 20N106W AND SW TO A CREST AT 17N140W. AN UPPER JET 50-90 KT IS INDICATED ALONG THE W PERIPHERY OF THE ANTICYCLONE ADVECTING UPPER MOISTURE FROM THE CENTRAL PACIFIC E AND E ACROSS THE NORTHERN RIDGE CREST SPILLING ACROSS SOUTHERN CALIFORNIA AND ARIZONA. UPPER DIFFLUENCE ALONG THE SOUTHERN PERIPHERY OF THIS LARGE RIDGE IS SUPPORTING THE CONVECTION ALONG THE MONSOON TROUGH AND EMBEDDED LOWS AS PREVIOUSLY DESCRIBED. THE DEBRIS MOISTURE IS FANNING OUT N TO ALONG 20N BETWEEN 107W AND 117W...AND FANNING OUT S TO THE EQUATOR AT 112W. OTHERWISE THE LARGE ANTICYCLONE IS SUPPRESSING CONVECTION ACROSS THE ENTIRE SUBTROPICAL PORTION OF THE DISCUSSION AREA. AN UPPER SHORTWAVE TROUGH EXTENDS SW ACROSS THE WESTERN GULF OF MEXICO AND OVER CENTRAL MEXICO AND CONTINUING S ACROSS THE DEEP TROPICS ALONG 14N100W INTO AN UPPER CYCLONE OVER THE EQUATOR AT 101W. THIS TROUGH SEPARATES THE UPPER FLOW OVER THE TROPICS AS BROAD RIDGING IS NOTED E OF THE TROUGH AND ENHANCING THE CONVECTION ALONG THE EASTERN SEGMENT OF THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED. SOME OF THE RESULTANT DEBRIS MOISTURE IS ADVECTED N ACROSS CENTRAL AMERICA E OF 87W...WITH THE MOSITURE TURNING E ACROSS THE SOUTHERN CARIBBEAN. ELSEWHERE AT THE LOW LEVELS...BROAD SURFACE RIDGING COVERS MUCH OF 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 TO 8 FT IN THE AREA BOUNDED BY 06N-09N BETWEEN 113W-116W. THIS AREA WILL SHIFT SLIGHTLY N ON SAT...THEN WINDS WILL DIMINISH TO 15 KT AND SEAS WILL SUBSIDE TO LESS THAN 8 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 MON NIGHT...THEN THE GRADIENT WILL RELAX WITH SEAS 4-5 FT ALONG THE ENTIRE WESTERN COAST OF THE BAJA PENINSULA THROUGH MID WEEK...WITH A SLIGHT BUILDING OF NW SWELL SUGGESTED N OF 28N LATE NEXT WEEK. REFRACTIVE SWELL RESULTING IN SEAS TO 3 FT 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 ON SAT...THEN PULSE AGAIN TO 20-25 KT STARTING LATE SUN NIGHT THROUGH CONTINUING THE MIDDLE OF NEXT WEEK WITH THE STRONGEST DRAINAGE FLOW OCCURRING LATE EACH NIGHT THROUGH A COUPLE OF HOURS AFTER SUNRISE. $$ NELSON