000 AXPZ20 KNHC 190956 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN DEC 19 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...TROPICAL LOWS... .A WELL DEFINED SURFACE LOW PRES CENTERED AT 09N113W IS ESTIMATED AT 1010 MB. SOUTHWESTERLY WINDS 15 TO 20 KT ARE NOTED WITHIN ABOUT 120 NM OVER THE SE QUADRANT WITH SEAS TO 8 FT. THE LOW IS EXPECTED TO MOVE W TO NEAR 09N118W 1008 MB IN 24 HOURS...AND NEAR 10N120W AT 1009 MB IN 48 HOURS WITH LITTLE CHANGE IN WINDS AND SEAS THROUGH 48 HOURS THEN WINDS AND SEAS ARE EXPECTED TO DIMINISH NEAR THE LOW AS CROSS EQUATORIAL SE WINDS SPREAD N OVER THE PACIFIC WATERS S OF 08N BETWEEN 118W AND 140W. CONVECTION HAS BEEN FLARING WITHIN ABOUT 150 NM OF THE LOW CENTER BUT IS CURRENTLY SUPPRESSED TO A FEW SHOWERS. .ANOTHER PERSISTENT SURFACE LOW PRES IS MEANDERING NEAR 07N87W AND ESTIMATED AT 1008 MB. SOUTHWESTERLY WINDS AT 15 TO 20 KT ARE NOTED WITHIN ABOUT 180 NM OVER THE SE QUADRANT WITH SEAS TO 8 FT. THE LOW IS EXPECTED TO MEANDER IN THE SAME AREA THROUGH 48 HOURS WITH LITTLE CHANGE IN WIND AND SEAS. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N78W TO THE LOW PRES NEAR 07N87W...CONTINUING W TO THE SECOND LOW PRES NEAR 09N113W...WITH AXIS DIPPING A LITTLE FURTHER S TO NEAR 06N127W THEN TURNING NW BEYOND 10N140W. SCATTERED MODERATE CONVECTION IS NOTED N OF 07N E OF 80W. ISOLATED MODERATE IS NOTED FROM 04N TO 08N BETWEEN 80W AND 90W AND ALSO WITHIN 150M NM OF 10N110W. ...DISCUSSION... AN UPPER ANTICYCLONE IS CENTERED AT 11N141W WITH A LOW LEVEL TROUGH EXTENDING FROM 08N145W TO 15N140W. INTENSE CONVECTION YESTERDAY HAS DECREASED THIS MORNING TO ONLY ISOLATED SHOWERS WITHIN ABOUT 240 NM OF 11N142W BUT A CLUSTER OF STRONG CONVECTION IS CURRENTLY FLARING NEAR 16.5N138W. THE ASSOCIATED DEBRIS MOISTURE IS NOTED OVER THE TROPICS FROM 06N TO 16N BETWEEN 135W AND 147W. AN UPPER TROUGH HAS MOVED INTO THE W PORTION OF THE DISCUSSION AREA EXTENDING FROM 32N130W TO 18N134W. THE ASSOCIATED SURFACE FRONT HAS SLOWED ALONG 30N131W TO 28N140W. A WELL DEFINED UPPER ANTICYCLONE IS CENTERED AT 21N118W WITH THE SURFACE HIGH AT 23N125W 1018 MB. DENSE UPPER DEBRIS MOISTURE...ORIGINATING IN THE CENTRAL PACIFIC...IS STREAMING E AND SE INTO THE UPPER TROUGH...THEN TURING NE AROUND THE PERIPHERY OF THE UPPER RIDGE...ROUGHLY OVER THE DISCUSSION AREA NW OF LINE FROM 32N123W TO 20N140W. THIS MOISTURE CONTINUES E ACROSS THE SOUTHWESTERN UNITED STATES. AN UPPER LEVEL CYCLONE IS NOTED OVER THE DEEP TROPICS AT 07N125W. THE UPPER LEVELS APPEAR VERY DRY AND SUPPRESSING CONVECTION UNDER THE LARGE ANTICYCLONE AND ALSO AROUND THE TROPICAL UPPER CYCLONE...ROUGHLY N OF 15N BETWEEN 125W AND 90W...AND S OF 15N BETWEEN 113W AND 130W. A SMALL UPPER ANTICYCLONE IS ESTIMATED NEAR 12N105W. CONVECTION ASSOCIATED WITH THE SURFACE LOW PRES PREVIOUSLY MENTIONED AT 09N113W IS OCCASIONALLY ENHANCED. THE DEBRIS MOISTURE FROM A PREVIOUS FLAREUP IS STILL NOTED WITHIN 240 NM OF 11N110W. A UPPER RIDGE EXTENDS W ACROSS THE SW CARIBBEAN AND COSTA RICA TO A CREST AT 09N90W. DEBRIS MOISTURE ORIGINATING FROM CONVECTION OVER NW COLOMBIA AND THE CONVECTION PREVIOUSLY DESCRIBED S OF PANAMA...IS ADVECTED W OVER THE TROPICS S OF 09N E OF 90W. OTHERWISE THE UPPER LEVELS ARE VERY DRY S OF 23N E OF 110W AND SUPPRESSING CONVECTION. A SURFACE COLD FRONT THAT EXTENDS FROM 32N129W TO 28N140W IS ACCOMPANIED BY A 20 TO 25 KT WIND SHIFT ALONG THE FRONT WITH SEAS TO 11 FT IN NW SWELL. SEVERAL SECONDARY NORTHERLY SURGES WILL PUSH THE NORTHERN SEGMENT OF THE FRONT E TO THE NORTHERN BAJA CALIFORNIA PENINSULA LATE MON. SEAS W OF THE FRONT WILL BUILD TO ABOUT 14 FT IN LONG PERIOD NW SWELL...BUT ARE EXPECTED TO SUBSIDE TO ABOUT 11 FT BEFORE REACHING THE NORTHERN BAJA CALIFORNIA PENINSULA. GAP WINDS...A COLD FRONT OVER THE SE GULF OF MEXICO IS CURRENTLY SUPPORTING 20 TO 25 KT NORTHERLY WINDS INTO...AND JUST DOWNSTREAM...OF THE GULF OF TEHUANTEPEC. GUIDANCE CONTINUES TO INDICATE THAT SOUTHERLY RETURN FLOW WILL BECOME ESTABLISHED OVER THE GULF OF MEXICO LATE TODAY DIMINISHING THE NORTHERLY WINDS IN THE GULF OF TEHUANTEPEC TO LESS THAN 20 KT. EXPECT TO SEE SOME LATE NIGHT DRAINAGE FLOW RESULTING IN NORTHERLY 15 TO 20 KT AROUND SUNRISE MON...TUE AND WED MORNINGS THIS WEEK...AND PERHAPS 20 TO 25 KT ON THU AND FRI MORNINGS. DEPENDING ON THE STRENGTH OF THE PERSISTENT LOW PRESSURE NEAR 07N87W...EXPECT NE WINDS TO SURGE AT 15 TO 20 KT IN THE GULF OF PAPAGAYO BEGINNING LATE TONIGHT BUT NOT PERSIST LONG ENOUGH TO BUILD 8 FT SEAS. $$ NELSON