000 AXPZ20 KNHC 121601 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE MAR 11 2013 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM A WEAK 1008 MB LOW AT 07N78W TO 08N86W THEN SSW TO 02N93W TO 01N102W TO 03N110W WHERE LOW LEVEL WINDS SUGGEST THAT IT TRANSITIONS TO AN ITCZ AXIS TO 04N120W TO 04N130W AND TO 03N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE MONSOON TROUGH AXIS BETWEEN 82W-85W...AND ALSO WITHIN 120 NM N OF THE MONSOON TROUGH AXIS BETWEEN 97W-100W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM N OF THE ITCZ AXIS BETWEEN 115W-118W. ...DISCUSSION... ALOFT... A LONGWAVE TROUGH PATTERN OVER CENTRAL N AMERICA HAS ITS MEAN AXIS EXTENDING SW ACROSS THE SW U.S. TO ACROSS THE CENTRAL GULF OF CALIFORNIA AND TO A BASE OVER THE TROPICAL PACIFIC AT 10N120W. TO ITS W...AN UPPER RIDGE IS AMPLIFYING NNE ACROSS THE WESTERN PORTION OF THE DISCUSSION AREA...WITH THE RIDGE CREST THEN PARALLELING THE NW COAST OF THE PACIFIC AND FARTHER TO THE NE. DEEP TROPICAL MOISTURE FROM THE CENTRAL PACIFIC IS STREAMING NEWD ON THE BACK SIDE OF THE RIDGE TO AROUND THE RIDGE CREST ...AND NE TOWARDS THE PACIFIC NW REGION OF THE U.S. SATELLITE WATER VAPOR SHOWS MODERATE TO STRONG SUBSIDENCE COVERING THE JUST ABOUT THE ENTIRE AREA W OF THE TROUGH AXIS. AS A RESULT... DRY AND STABLE ATMOSPHERIC CONDITIONS ARE ALLOWING FOR PATCHES OF BROKEN TO SCATTERED STRATOCUMLUS CLOUDS TO MOVE WESTWARD OVER THE AREA W OF 130W...AND ALSO S OF 20N BETWEEN 120W AND 130W. OVER THE EASTERN PORTION OF THE AREA E OF THE ABOVE MENTIONED TROUGH...BROAD SCALE MID/UPPER LEVEL RIDGING IS NOTED WITH A AN ANTICYCLONE CENTER NEAR 11N88W. WEAK UPPER DIFFLUENCE AT THE BASE OF THE TROUGH BETWEEN THE TROUGH AND RIDGE...AND IN COMBINATION WITH LOW LEVEL CONVERGENCE CONTINUES TO ENHANCE CONVECTION ALONG AND NEAR THE ITCZ AND MONSOON TROUGH AS DESCRIBED ABOVE. THE RESULTANT UPPER DEBRIS MOISTURE IS BEING ADVECTED NE ALONG THE PERIPHERY OF THE UPPER RIDGE IN THE FORM OF A 505 NM WIDE TROPICAL PLUME THAT CROSSES CENTRAL OLD MEXICO AND STRETCHES FURTHER E TO WELL E OF THE AREA. AT THE SURFACE... A WEAKENING 1026 MB HIGH IS N OF THE AREA AT 36N131W WITH A RIDGE EXTENDING SEWD TO 31N128W TO NEAR 21N115W. THE TIGHT PRES GRADIENT TO THE SW OF THE RIDGE IS SUPPORTING NE TRADES OF 20-25 KT OVER THE AREA FROM 07N-14N W OF 135W WHERE SEAS ARE 8-10 FT. WITH THE HIGH AND ASSOCIATED RIDGE FORECAST TO WEAKEN OVER THE NEXT 48 HRS...THE PRES GRADEINT WILL RELAX ALLOWING FOR THIS AREA OF TRADES TO SHRINK FROM E TO W WITH NE WINDS OF 15-20 KT EXPECTED FROM 03N-19N W OF 129 WITH SEAS TO 9 FT MAINLY IN A NE SWELL. GAP WINDS... GULF OF TEHUANTEPEC...HIGH PRESSURE IN THE WAKE OF A COLD FRONT OVER THE EASTERN BAY OF CAMPECHE IS CURRENTLY SURGING THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC AT MINIMAL GALE FORCE...WITH SEAS TO 11 FT. THESE MINIMAL GALE CONDITIONS ARE EXPECTED TO PERSIST THROUGH LATE WED. A REINFORCING NORTHERLY SURGE OVER THE GULF OF MEXICO WILL INCREASE TO GULF OF TEHUANTEPEC DRAINAGE FLOW TO 45 KT WED NIGHT...AND PERSIST THROUGH EARLY ON THU. SHORT-LIVED MINIMAL STORM CONDITIONS ARE STILL A POSSIBILITY FROM EARLY ON THU TILL LATE THU MORNING OR EARLY THU AFTERNOON. THE SOUTHERN EXTENT OF THE GALE FORCE WINDS ARE EXPECTED TO REACH AS FAR S AS 13N96.5W ON THU...WITH RESULTANT SEAS MAXING ABOUT 19 FT. OVERALL...THE GRADIENT WILL BEGIN TO RELAX LATE THU...WITH GALE CONDITIONS ENDING LATE SAT MORNING OR EARLY AFTERNOON SAT. GULF OF PAPAGAYO...NE WINDS WILL PULSE AT 15 TO 20 KT INCREASING TO 20 TO 25 KT LATE TONIGHT. MODELS FORECAST THESE CONDITIONS TO SPREAD WSW...AND EXIST OVER AN AREA FROM 09N-11N E OF 89W BY EARLY THU WITH SEAS TO 8 FT. $$ AGUIRRE