000 AXPZ20 KNHC 072148 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN OCT 07 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... TROPICAL STORM OLIVIA AT 15.5N 120.8W 998 MB AT 07/2100 UTC MOVING N-NW OR 340 DEGREES AT 05 KT IN RESPONSE TO AN UPPER CYCLONE E OF THE CENTER NEAR 14N116W. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. SCATTERED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 150 NM OVER THE ENTIRE N SEMICIRCLE AND WITHIN 90 NM OVER THE S QUADRANT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ALSO NOTED WELL OUT FROM CENTER OVER THE NE QUADRANT...WITHIN 60 NM OF 17N118W. OLIVIA MAY STRENGTHEN SLIGHTLY OVER THE DAY OR SO THEN THE FORECAST TRACK WILL MOVE OVER COOLER OCEAN WATERS. FOR FURTHER DETAILS SEE AWIPS/WMO HEADERS MIATCMEP5 AND WTPZ25 KNHC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS W ACROSS THE SOUTHERN CARIBBEAN BETWEEN 11N-12N FROM EXTREME N COLOMBIA TO ACROSS THE NORTHERN COSTA RICA TO THE PACIFIC COAST AT 11N86W...THEN CONTINUES SW TO 07N104W TO 09N112W WHERE IT LOSES IDENTITY IN SOUTHERLY FLOW TO THE S OF TS OLIVIA. THE MONSOON TROUGH RESUMES SW OF OLIVIA AT 12N124W TO 08N131W TO 08N134W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES W TO BEYOND 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 120 NM EITHER SIDE OF A LINE FROM 07N82W TO 09.5N86W TO 08N90W THEN NARROWS TO 30 NM WIDE FROM 07N95W TO 07N97W. SIMILAR CONVECTION IS NOTED WITHIN 30 NM EITHER SIDE OF A LINE FROM 12N95W TO 06N108W. SCATTERED MODERATE CONVECTION IS OBSERVED WITHIN 30 NM EITHER SIDE OF A LINE FROM 10N104W TO 08N112W AND 60 NM EITHER SIDE OF A LINE FROM 13N124W TO 08N129W TO 08N138W. SCATTERED MODERATE ISOLATED STRONG CONVECTION...ACCOMPANIED BY NUMEROUS LIGHTNING STRIKES...IS OBSERVED OVER AND WITHIN 15 NM OF THE PACIFIC COAST OF GUATEMALA AND EXTENDING N ALONG THE COAST OF EXTREME SW MEXICO AT 15.6N93W. ...DISCUSSION... A SHORTWAVE TROUGH HAS MOVED OVER THE NW PORTION OF THE DISCUSSION AREA ALONG 32N132W TO 26N136W WITH A BAND OF UPPER MOISTURE ROTATING THROUGH THE TROUGH AND SHOULD MOVE ACROSS THE CALIFORNIA COAST FROM 34N-37N WITHIN THE NEXT FEW HOURS. A SECOND BAND OF UPPER MOISTURE IS ALREADY MOVING E ACROSS THE NORTHERN BAJA CALIFORNIA PENINSULA CONTINUING E ACROSS SOUTHERN ARIZONA AND NEW MEXICO MERGING WITH A SIGNIFICANT MOISTURE BAND MOVING ACROSS THE ENTIRE SE CONUS. AN UPPER LEVEL ANTICYCLONE IS POSITIONED E OF TROPICAL STORM OLIVIA AT 14N116W WITH UPPER RIDGES EXTENDING N BEYOND 32N115W...SE TO A CREST AT 13N103W AND W TO A CREST AT 17N129W. AN UPPER JET DETECTED BY CLOUD MOTION VECTORS ALONG THE NW PERIPHERY OF THE ANTICYCLONE APPEARS TO HAVE WEAKENED TO ABOUT 50 KT AS IT CONTINUES THROUGH POINTS 29N126W TO 32N115W. THE DEBRIS MOISTURE FROM OLIVIA IS ADVECTED N AND NE TO ALONG 23N BETWEEN 118W-112W WHERE IT TURNS SE AND APPEARS TO REMAIN W OF THE MEXICAN COAST. AN UPPER SHORTWAVE TROUGH OVER THE CENTRAL CONUS EXTENDS SW ACROSS THE WESTERN GULF OF MEXICO AND OVER CENTRAL MEXICO TO BASE NEAR 14N100W. THE UPPER DIFFLUENCE E OF THE TROUGH ENHANCED CONVECTION ALONG THE MEXICAN COAST NEAR 100W EARLIER...WITH THE DEBRIS MOISTURE NOW ADVECTED NE ACROSS MEXICO ALONG 17N... MERGING WITH ADDITIONAL DENSE MOISTURE OVER THE ENTIRE GULF OF MEXICO E OF THE SAME UPPER TROUGH. THIS MOISTURE PLUME CONTINUES E ACROSS MOST OF FLORIDA INTO THE W CENTRAL ATLANTIC. AN UPPER ANTICYCLONE OVER THE WESTERN CARIBBEAN AT 16N80W HAS ITS ANTICYCLONIC ENVELOPE EXTENDING S OVER THE DISCUSSION AREA TO THE N OF 05N AND E OF 96W. THE ASSOCIATED UPPER DIFFLUENCE IS SUPPORTING THE CONVECTION ALONG THE EASTERN SEGMENT OF THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED. DENSE DEBRIS MOISTURE IS OBSERVED OVER THE AREA N OF 05W E OF 90W...AND FOR THE MOST PART IS ADVECTED N ACROSS CENTRAL AMERICA TO THE E OF GUATEMALA. ELSEWHERE AT THE LOW LEVELS...SURFACE HIGH PRESSURE IS NEAR 29N127W WITH BROAD RIDGING COVERING THE DISCUSSION AREA N OF 22N W OF THE BAJA PENINSULA. THE NW WINDS HAVE DIMINISHED THIS AFTERNOON TO 15-20 KT E OF THE RIDGE IN THE AREA N OF 27N BETWEEN 117W AND THE NORTHERN BAJA CALIFORNIA PENINSULA...WITH SEAS CONTINUING AT 5-8 FT IN NW SWELL. EXPECT THESE NW WINDS TO FURTHER DIMINISH TO 10-15 KT ALONG THE ENTIRE W COAST OF THE BAJA PENINSULA ON MON...WITH SEAS OF 4-7 FT IN NW SWELL... SUBSIDING TO 3-5 FT WED AND THU. EXTENDED GUIDANCE SHOWS THE SURFACE HIGH MEANDERING NEAR 28N125W LATE THIS WEEK...BUT THE GRADIENT WILL TIGHTEN ALONG THE NW COAST OF BAJA LATE FRI WITH NW WINDS INCREASING TO 15-20 KT AND SEAS BUILDING 4-7 FT INTO THE WEEKEND. GAP WINDS...NORTHERLY WINDS AT 20-25 KT ARE EXPECTED TO PULSE ACROSS THE GULF OF TEHUANTEPEC BEGINNING LATE TONIGHT AND INCREASE TO 20-30 KT LATE MON NIGHT...RELAXING SOME TUE NIGHT...20-25 KT...BUT RETURNING BACK TO 25-30 KT LATE WED NIGHT. THE STRONGEST DRAINAGE FLOW WILL OCCUR LATE EACH NIGHT THROUGH A COUPLE OF HOURS AFTER SUNRISE EACH MORNING. MODEL GUIDANCE IS BEGINNING TO CONCUR ON A SURFACE LOW DEVELOPING ALONG THE MONSOON TROUGH NEAR 10N90W ON TUE WITH THE LOW MOVING W-NW THEREAFTER...WITH THIS LOW PRES NOW POSTED ON MARINE GRAPHICS. THE GFS HAS BEEN THE MOST AGGRESSIVE MODEL AND PREVIOUS FORECAST GRIDS HAVE USED MODEL BLENDS TO TONE DOWN THE GFS SOLUTION. NOTING THAT THE LATEST GFS RUN CONTINUES TO INDICATE LOW PRES DEVELOPMENT...BUT NOT AGGRESSIVE. THE LOW DEPICTED IN THE MODEL DATA TENDS TO AMPLIFY THE DRAINAGE FLOW THROUGH THE ISTHMUS OF TEHUANTEPEC LATE IN WEEK AND THAT HIGH BIAS HAS ALSO BEEN ADJUSTED AS MUCH AS POSSIBLE. $$ NELSON