000 AXPZ20 KNHC 181005 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI NOV 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0845 UTC. ...SPECIAL FEATURE... A 1008 MB AREA OF LOW PRES IS EMBEDDED IN THE MONSOON TROUGH NEAR 9N96W MOVING W AROUND 10 KT. SCATTERED STRONG CONVECTION HAS INCREASED DURING THE PAST SEVERAL HOURS WITHIN 90 NM OF THE CENTER IN THE NW SEMICIRCLE. S-SW WINDS OF 20 KT ARE PRESENT FROM 4N-9N BETWEEN 92W-98W. IF THE CURRENT TREND OF INCREASING CONVECTION CONTINUES ...AND WITH THE CIRCULATION BECOMING TIGHTER AROUND THE LOW CENTER EXPECT 20-25 KT WINDS TO BE WITHIN 180 NM NE AND 60 NM SW SEMICIRLCE OF THE LOW BY SAT EVENING WITH SEAS BUILDING TO 9 FT. WINDS MAY ACTUALLY REACH TO OR NEAR 30 KT AROUND THAT TIME OR TOWARDS SUN AFTERNOON OR EVENING. ENVIRONMENTAL CONDITIONS ARE GENERALLY CONDUCIVE FOR GRADUAL DEVELOPMENT OF THIS SYSTEM...AND THE LOW HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 24-48 HOURS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 10N86W TO 11N90W TO LOW PRES NEAR 9N96W TO 8N101W TO 8N112W WHERE IT ENDS. LOW LEVEL WINDS THEN INDICATE THAT THE INTERTROPICAL CONVERGENCE ZONE AXIS BEGINS AT 10N127W AND CONTINUES TO BEYOND THE AREA AT 08N140W. SCATTERED MODERATE ISOLATED STRONG IS WITHIN 60 NM OF THE TROUGH BETWEEN 91W AND 94W...AND WITHIN 120 NM S OF THE ITCZ BETWEEN 131W AND 133W. SCATTERED STRONG IS WITHIN 120 NM S OF THE ITCZ W OF 136W. ...DISCUSSION... AN UPPER LEVEL CYCLONIC CIRCULATION HAS MOVED INTO THE FAR NW PORTION OF THE DISCUSSION AREA NEAR 31N137W. AN ASSOCIATED UPPER LEVEL TROUGH EXTENDS FROM THE CYCLONIC CIRCULATION TO 25N140W. BROAD RIDGING IS QUICKLY DAMPENING OUT AHEAD OF THE TROUGH AS IT SLIDES EASTWARD TO OVER THE SW U.S. AND BAJA CALIFORNIA. EXTENSIVE MID/UPPER LEVEL MOISTURE IS STREAMING EASTWARD INTO THE AREA AROUND THE BASE OF THE TROUGH...AND RAPIDLY REACHES MOST OF CALIFORNIA AND THE WESTERN U.S. MAINLY ZONAL UPPER LEVEL FLOW IS CONFINED TO THE AREA OF THE BROAD RIDGING AHEAD OF THE TROUGH. WATER VAPOR SATELLITE IMAGERY INDICATES STRONG SUBSIDENCE WITH DRY AND STABLE AIR AT THE MID AND UPPER LEVELS ACROSS THE AREA N OF 17N E OF 120W. AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS S OF EL SALVADOR NEAR 10N89W WITH A RIDGE AXIS EXTENDING FROM IT TO NEAR 13N115W. UPPER LEVEL DIFFLUENCE OVER THIS REGION IS ENHANCING CONVECTION ASSOCIATED WITH THE LOW DESCRIBED UNDER SPECIAL FEATURES. IN THE DEEP TROPICS...AN UPPER LEVEL CYCLONIC CIRCULATION IS JUST TO THE S OF THE EQUATOR WITH AN ASSOCIATED UPPER TROUGH FROM 00N121W TO 09N120W. DRY AND STABLE AIR COVERS THE WATERS S OF 06N AND W OF 93W. AT THE SURFACE...A RIDGE EXTENDS FROM NEAR 32N137W SE TO 21N115W. HIGH PRES COVERS THE AREA N OF 16N AND W OF 115W. NW SWELL OF 8-10 FT COVERS THE AREA N OF 27N BETWEEN 119W AND 129W. THIS SWELL WILL SUBSIDE TO LESS THAN 8 FT WITHIN THE NEXT 24 HOURS. A NEW SET OF LARGE NW SWELL WITH PEAK WAVE PERIODS OF 16-18 SECONDS WILL PUSH S OF 30N EARLY SAT MORNING WITH SEAS BUILDING TO 13 FT ALONG 30N BY SAT EVENING. A WEAKENING SURFACE TROUGH IS ANALYZED ALONG THE ITCZ FROM 14N120W TO 10N126W. ISOLATED TO SCATTERED MODERATE CONVECTION IS WITHIN 60-120 NM EITHER SIDE OF THE TROUGH. AN EARLIER SCATTEROMETER PASS CAPTURED NE-E 20 KT WINDS WITHIN 180 NM NW OF THE TROUGH WITH AN AREA OF 8-9 FT SWELL ELSEWHERE FROM 11N TO 15N BETWEEN 118W AND 126W. THE TROUGH IS FORECAST TO WEAKEN AND DISSIPATE DURING THE NEXT 18 HOURS. GAP WINDS...STRONG HIGH PRES IS BUILDING IN BEHIND A COLD FRONT MOVING THROUGH THE SW GULF OF MEXICO RESULTING IN A TIGHT PRES GRADIENT ACROSS SOUTHERN MEXICO. THIS IS RESULTING IN WINDS TO GALE FORCE IN THE GULF OF TEHUANTEPEC AND A GALE WARNING IS NOW IN EFFECT THROUGH EARLY THIS AFTERNOON. $$ AGUIRRE