000 AXPZ20 KNHC 041605 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE OCT 04 2011 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 1545 UTC. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 10N86W TO 12.5N94W TO 12N102W TO A 1009 MB LOW AT 11N110W TO 10N127W TO 7N137W WHERE LOW LEVEL WINDS INDICATE THAT THE ITCZ AXIS BEGINS AND EXTENDS TO BEYOND 7N140W. SCATTERED MODERATE TO STRONG CONVECTION IS S OF THE TROUGH WITHIN 45 NM OF LINE FROM 7N95W TO 9N100W TO 10N102W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM N OF THE TROUGH BETWEEN 102W-108W AND 115W-122W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE TROUGH BETWEEN 112W-114W...AND ALSO S OF THE TROUGH FROM 6N-8N BETWEEN 81W-84W. ...DISCUSSION... ...N OF 18N... RATHER FAST MOVING AND HIGHLY AMPLIFIED LARGE SCALE SYSTEMS ARE N OF THE DISCUSSION AREA. THE FIRST IS VERY SHARP DEEP LAYER TROUGH NOW MOVING OVER CALIFORNIA AND THE NW PACIFIC AREA OF THE U.S. THE TROUGH WILL CONTINUE TO MOVE FURTHER INLAND THROUGH WED. THE TAIL END OF THE TROUGH IS FORECAST TO SHEAR OFF AND DEVELOP INTO A CYCLONIC CIRCULATION THAT MOVES WESTWARD TO NEAR 19N140W BY TONIGHT AND TO W OF THE AREA NEAR 19N144W BY LATE WED. A DISSIPATING SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH IS MOVING INLAND SOUTHERN CALIFORNIA...AND STRETCHES FROM 32N119W SW TO 27N127W. SCATTERED TO BROKEN LOW CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF THE FRONT. BEHIND THE FRONT...A HIGH PRES RIDGE IS BUILDING ESE FROM 27N140W TO NEAR 26N120W. HIGH PRES COVERS THE AREA N OF 18N AND W OF 120W. THE FRONT IS FORECAST TO WASH BY 24 HOURS AS IT LOSES ITS UPPER SUPPORT. HOWEVER...WINDS WILL BE LESS THAN 20 KT AS THE UPPER TROUGH MOVES INLAND. WINDS NW OF THE FRONT WILL BE LESS THAN 20 KT...BUT A NW SWELL WILL BUILD SEAS UP TO 8 OR 9 FT THROUGH THE NEXT 18-24 HOURS BEFORE SUBSIDING. ...S OF 18N... UPPER ANTICYCLONIC FLOW...MOSTLY INDUCED BY MONSOON CONVECTION ...DOMINATES THIS AREA OF THE REGION. THE MID/UPPER LEVEL RIDGE EXTENDS E TO W FROM AN ELONGATED ANTICYCLONE OVER CENTRAL AMERICA WESTWARD ALONG 16N TO 115W...THEN SOUTHWESTWARD TO A COL REGION AT 13N137W. ANOTHER MID/UPPER RIDGE EXTENDS NORTHWESTWARD FROM THE COL REGION TO AN ANTICYCLONE WELL W OF THE DISCUSSION AREA. ABUNDANT DEEP LEVEL ATMOSPHERIC ALONG AND NEAR THE MONSOON TROUGH IS FURTHER AIDED BY DIFFLUENCE OVER AND NEAR THE MID/UPPER RIDGE. A TIGHT PRES GRADIENT OVER MEXICO PRIMARILY DUE TO STRONG HIGH PRES OVER THE GULF OF MEXICO CONTINUES TO ALLOW FOR N-NE WINDS OF 20-25 KT TO FUNNEL INTO THE GULF OF TEHUANTEPEC WITHIN 60 NM EITHER SIDE OF A LINE FROM 16N95W TO 15N95W TO 13.5N97W WITH SEAS 8-10 FT. WITH THE GRADIENT STAYING QUITE TIGHT THROUGH THE NEXT 24 HRS THESE WINDS WILL CHANGE LITTLE CHANGE...BUT SEAS ARE FORECAST TO BE 8 OR 9 FT. BY 48 HRS...N-NE WINDS THROUGH THE GULF OF TEHUANTEPEC WILL DIMINISH TO 20 KT WITH SEAS TO 8 FT. FURTHER DOWNSTREAM FROM THE GULF OF TEHUANTEPEC...THESE WINDS BECOME NE-E AND DIMINISH TO 20 KT AS THEY CONTINUE TO IMPINGE INTO THE MONSOON TROUGH WITH SEAS 8-10 FT. THIS PROLONGED NE FLOW INTO THE MONSOON TROUGH HAS HELPED INDUCED A 1009 MB LOW NEAR 11.5N111W 1009 MB AS IT COMES INTO CONFLUENCE WITH SW FLOW OF 20 KT FROM 7N-10N BETWEEN 109W-114W. WITH LITTLE CHANGE EXPECTED IN THE NE FLOW OF 20 KT OVER THE NEXT 48 HRS...ANOTHER LOW IS FORECAST TO DEVELOP NEAR 11N101W 1009 MB IN 24 HRS. EXPECT THIS SECOND LOW TO SLOWLY INTENSIFY AS TRACKS IN A GENERAL NW DIRECTION OVER THE NEXT 48 HRS. PRESENTLY WINDS OF 20 KT WITH SEAS LESS THAN 8 FT ARE WITHIN 150 NM IN THE NW SEMICIRCLE OF THE FIRST LOW...AND ARE EXPECTED TO CHANGE LITTLE THROUGH THE NEXT 48 HRS. WITH MORE VORTICITY ENTRAINED INTO THE SECOND LOW FROM THE UPSTREAM GULF OF TEHUANTEPEC NE FLOW DURING THE NEXT COUPLE OF DAYS...EXPECT FOR IT TO SLOWLY INTENSIFY AS IT TRACKS NORTHWESTWARD. WINDS OF 20 KT WILL BE WITHIN 150 NM N SEMICIRCLE OF THE SECOND LOW AND CHANGE LITTLE DURING THE 48 HRS...BUT BY THEN WINDS OF 20-25 KT ARE EXPECTED TO MATERIALIZE WITHIN 240 NM IN THE SE SEMICIRCLE. SEAS TO 8 FT ASSOCIATED WITH THE SECOND LOW ARE FORECAST TO BUILD TO 8-11 FT IN 48 HRS. ELSEWHERE FROM 7N-11N BETWEEN 114W-121W S-SW WINDS OF 20-25 KT WITH SEAS TO 9 FT ARE EXPECTED BY 48 HRS. ELSEWHERE...A WEAK PRES PATTERN WILL REMAIN THROUGH THE NEXT COUPLE OF DAYS. SEAS TO 8 FT IN MERGING SW AND NW SWELLS ARE S OF 1N BETWEEN 115W-126W. BY 24 HRS...EXPECT WINDS LESS THAN 20 KT WITH SEAS TO 8 OR 9 FT PRIMARILY IN A SW SWELL COMPONENT S OF 10N BETWEEN 98W-124W...AND REACHING N TO 14N BETWEEN 95W-117W BY 48 HRS. $$ AGUIRRE