000 AXPZ20 KNHC 190345 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT NOV 19 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...SPECIAL FEATURE... AN 1006 MB AREA OF LOW PRES IS EMBEDDED IN THE MONSOON TROUGH NEAR 09.5N97W MOVING W AROUND 5 KT. ASSOCIATED CONVECTION HAS INCREASED SOMEWHAT DURING THE PAST SEVERAL HOURS AS THE LOW MOVES AWAY FROM DRIER AND MORE STABLE AIR FLOWING SW FROM THE GULF OF TEHUANTEPEC. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 150 NM OF THE LOW CENTER. NE-E 20 KT WINDS ARE FROM 09.5N TO 13N BETWEEN 95W AND 101W...WITH S-SW 20 KT WINDS FROM 04N TO 09.5N BETWEEN 92W AND 100W. SEAS OF 8-9 FT IN MIXED NE AND SW SWELL COVERS THESE SAME AREAS. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR THE LOW TO DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 24-48 HOURS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 09N79W TO 10N86W TO LOW PRES NEAR 09.5N97W TO LOW PRES NEAR 07.5N112W TO 08N118W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N118W TO 10N126W THEN RESUMES FROM 10N129W TO 08N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE ITCZ W OF 130W. ...DISCUSSION... AN UPPER LEVEL TROUGH REACHES FROM THE CALIFORNIA CHANNEL ISLANDS INTO THE AREA NEAR 32N127W TO 24N140W. PLENTIFUL MID TO UPPER LEVEL MOISTURE IS BEING ADVECTED TO THE NE WITHIN 360-420 NM AHEAD OF THE TROUGH AXIS. ADDITIONAL MID TO UPPER LEVEL MOISTURE IS PRESENT FROM 16N TO 24N W OF 128W...WHICH IS BEING PUMPED UP FROM THE DEEP TROPICS S OF THE HAWAIIAN ISLANDS. ANOTHER UPPER LEVEL TROUGH STRETCHES FROM NEAR 23N116W TO 13N124W. TROPICAL MOISTURE IS WITHIN 240-300 NM E OF THE TROUGH FEEDING TO THE NE FROM THE ITCZ. WATER VAPOR SATELLITE IMAGERY INDICATES DRY AND STABLE AIR UNDER MODERATE TO STRONG SUBSIDENCE N OF 15N E OF 110W TO ACROSS MEXICO. AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS S OF GUATEMALA NEAR 11N92W WITH A RIDGE AXIS EXTENDING FROM IT TO NEAR 13N117W. UPPER LEVEL DIFFLUENCE OVER THIS REGION IS ENHANCING CONVECTION ASSOCIATED WITH THE SURFACE LOW DESCRIBED IN THE SPECIAL FEATURE SECTION ABOVE. AN ELONGATED UPPER LEVEL ANTICYCLONIC CIRCULATION IS NEAR 09N135W WITH A RIDGE AXIS ALONG 09N/10N W OF 125W. UPPER LEVEL DIFFLUENCE OVER THIS REGION IS ALSO ENHANCING CONVECTION ALONG THE ITCZ AS IS DESCRIBED IN THE SECTION ABOVE. ELSEWHERE AT THE SURFACE...A RIDGE EXTENDS FROM NEAR 32N140W SE TO 17N105W. A SMALL AREA OF LINGERING 8 FT NW SWELL RESIDES FROM N OF 29N BETWEEN 119W AND 123W. THIS SWELL WILL DECAY TO LESS THAN 8 FT DURING THE NEXT 12 HOURS WHILE A NEW SET OF LARGER NW SWELL WITH PEAK WAVE PERIODS OF 16-18 SECONDS PROPAGATES INTO THE NW PORTION OF THE DISCUSSION WATERS. A FRONTAL TROUGH WILL PRECEDE THIS SWELL ALTHOUGH ASSOCIATED WINDS ARE FORECAST TO REMAIN LESS THAN 20 KT WITH THIS FEATURE. A REINFORCING COLD FRONT WILL ARRIVE EARLY SUN MORNING REACHING FROM 30N126W TO 28N135W TO 29N140W BY 12 UTC SUN...THEN WILL WEAKEN AS IT EXTENDS FROM 30N122W TO 27N125W TO 26N140W BY 00 UTC MON. THE NW SWELL WILL BUILD TO 13/14 FT ALONG 30N BETWEEN 36-48 HOURS. ALSO...AN AREA OF 20-25 KT WESTERLY WINDS WILL ACCOMPANY THIS REINFORCING FRONT OVER THE FAR N CENTRAL WATERS. A SURFACE TROUGH IS ANALYZED ALONG THE ITCZ EXTENDING FROM 13N124W TO 09N129W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 08N TO 11N BETWEEN 125W AND 129W. AN EARLIER ASCAT SCATTEROMETER PASS CAPTURED 20 KT NE-E WINDS AHEAD OF THE TROUGH WHILE AN EARLIER ALTIMETER PASS SAMPLED 8 FT SEAS IN THIS SAME GENERAL AREA. THE TROUGH IS FORECAST TO MOVE W THROUGH 48 HOURS WITH THE AREA OF 20 KT WINDS AND 8 FT SEAS TRANSLATING WESTWARD TOWARD 140W AS WELL. GAP WINDS...THE PRES GRADIENT IS GRADUALLY WEAKENING OVER THE GULF OF TEHUANTEPEC REGION ALTHOUGH N-NE 20-25 KT WINDS AND SEAS TO 9 FT PERSIST. THESE WINDS AND SEAS WILL DIMINISH AND SUBSIDE BY EARLY SAT AFTERNOON AS THE GRADIENT CONTINUES TO RELAX. $$ LEWITSKY