000 AXPZ20 KNHC 150949 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT JAN 15 2011 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 0930 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS IS CENTERED ALONG 8N84W 5N93W 6N110W 7N123W 7N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 117W-120W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 130W-133W...AND ALSO W OF 137W. ...DISCUSSION... THE MAIN SURFACE FEATURE IS A 1030 MB HIGH NEAR 32N135W WITH A RIDGE SE TO 24N127W TO 19N120W. THE UPPER LEVEL ANTICYCLONE THAT SUPPORTS THIS HIGH IS JUST NE OF THE AREA HAVING SHIFTED ESE TO JUST ALONG THE SRN CALIFORNIA COAST. A TIGHT PRES GRADIENT ON THE SOUTHERN PERIPHERY OF THE RIDGE CONTINUES TO MAINTAIN A LARGE AREA OF NE TO E 20 TO 25 KT NE TRADE WINDS FROM GENERALLY 8N TO 25N W OF 120W AS PARTIALLY DEPICTED IN AN ASCAT PASS FROM NEAR 0530 UTC. SIGNIFICANT WAVE HEIGHTS OF 8 TO 12 FT ARE OCCURRING DUE TO A COMBINATION OF NE WIND WAVES AND OF NW SWELLS GENERATED BY A STORM CENTER WELL NW OF THE REGION. THE HIGH CENTER IS FORECAST TO MERGE WITH ANOTHER HIGH NEAR 34N132W BY LATE TONIGHT WHILE WEAKENING SLIGHTLY. THIS WILL RELAX THE PRES GRADIENT SOME ALLOWING FOR THE TRADES TO DIMINISH TO 20 KT OVER THE AREA BOUNDED FROM 11N TO 19N W OF 133W BY 48 HOURS...AND FOR SWELLS TO SUBSIDE TO 9 FT. W OF THE UPPER LEVEL ANTICYCLONE AND GENERALLY W OF 130W... A LARGE DEEP LAYER TROUGH STRETCHES INTO THE FAR NW CORNER OF THE AREA AND SWD NEAR 141W. LATEST SERIES OF SATELLITE WATER VAPOR IMAGERY IS SHOWING THAT THE SOUTHERN PORTION OF THE TROUGH IS TRANSFORMING INTO A LARGE CYCLONIC VORTEX FROM 3N TO 25N W OF 132W. WITH THE UPPER LEVEL FLOW TO THE E OF THE VORTEX BEING QUITE EXTENSIVE IT IS ALSO PROVIDING MOISTURE AND DIVERGENT FLOW ALOFT OVER ALONG AND N OF THE ITCZ TO 20N AND BETWEEN 100W AND 140W. THESE INGREDIENTS IN COMBINATION WITH WEAK SURFACE TROUGHS MOVING WWD THROUGH THE ITCZ ALONG 131W AND 121W FROM 5N TO 10N ARE SIGNIFICANTLY ENHANCING THE ITCZ CONVECTION AS DESCRIBED ABOVE. THE TROUGHS ARE ALSO HELPING TO SUPPORT THE TIGHT PRES GRADIENT ON THE SOUTHERN PERIPHERY OF THE RIDGE. THE UPPER LEVEL CYCLONIC VORTEX IS FORECAST TO MOVE W OF THE REGION TONIGHT... THEN BECOME ABSORBED INTO ANOTHER DEEP LAYER TROUGH ON SUN. THE MOIST SSW FLOW E OF THE CYCLONIC VORTEX IS PRODUCING MOSTLY BROKEN HIGH CLOUDS...WHICH ARE BEING DERIVED FROM ITCZ CONVECTION. THE CLOUDS ARE BEING CHANNELED N AND NE BY THE FLOW TO 20N...AND EASTWARD TOWARDS SOUTHERN MEXICO IN ADVANCE OF AN UPPER LEVEL TROUGH THAT IS PUSHING SEWD FROM NRN MEXICO SW TO JUST S OF SRN BAJA CALIFORNIA AND TO NEAR 18N118W. WITH BROAD DEEP SCALE RIDGING REMAINING IN PLACE OVER MUCH OF THE AREA W OF 115W...EXPECT UPPER LEVEL ATMOSPHERIC ENERGY TO CONTINUE TO STAY WELL N OF THE AREA THROUGH SUN NIGHT WITH NEAR FUTURE COLD FRONTS BLOCKED FROM ENTERING THE REGION AND BY PASS THE REGION WELL TO THE N. RECENT RUNS OF THE GFS MODEL HAVE BACKED DOWN ON BEING AGGRESSIVE WITH THE WINDS ON DEVELOPING A LOW ON THE WRN MOST SURFACE TROUGH ALONG 131W LATE THIS WEEKEND. GLOBAL MODELS TEND TO KEEP WEAK LOWS ALONG THE ITCZ FOR THE MOST PART. SO WILL FORECAST A WEAK 1009 MB LOW TO DEVELOP ON THIS TROUGH ONCE IT MOVES TO JUST W OF THE AREA SUN NIGHT. A STRONG PRES GRADIENT AS A RESULT OF STRONG HIGH OVER THE WRN CONUS AND LOWER PRES OVER THE NW MEXICO CONTINUES TO PRODUCE NW WINDS OF 20-25 KT THROUGH THE GULF OF CALIFORNIA N OF 23N. THE GRADIENT WILL BEGIN TO SLACKEN OVER THE NEXT 24-36 HOURS... ALLOWING FOR THESE WINDS TO DIMINISH TO 20 KT FROM 24N TO 28N IN 24 HOURS AND TO LESS THAN 20 KT IN 48 HOURS. GAP WINDS... GULF OF TEHUANTEPEC GALE WINDS ARE WINDING DOWN AS RETURN SE TO S FLOW SETS UP OVER THE WESTERN GULF OF MEXICO AND THE RESPONSIBLE AREA OF TIGHT PRES GRADIENT RELAXES OVER SE MEXICO. CURRENT N TO NE WINDS OF 30 TO 40 KT WILL DIMINISH TO MINIMAL GALE FORCE IN 12 HOURS...AND TO LESS THAN GALE STRENGTH IN 18 HOURS OR SHORTLY BEFORE. THE MARINE ISSUE IN 24 HOURS WILL BE MIXED NE AND SW SWELLS PRODUCING SEAS OF 8 TO 11 FT S OF 13N BETWEEN 92W AND 120W...BUT BY 48 HOURS ONLY 8 FT SEAS SHOULD BE SEEN OVER THE SECTOR BOUNDED FROM 4N TO 12N AND BETWEEN 100W AND 120W. AN ASCAT PASS FROM AROUND 0340 UTC CAPTURED NE WINDS OF 20 KT THROUGH THE GULF OF FONSECA AND PAPAGAYO. HOWEVER...AS WESTERN CARIBBEAN TRADES WEAKEN THROUGH SUN NIGHT THE FILTERING OF THE TRADES THROUGH SOUTHERN CENTRAL AMERICA WILL CEASE ALLOWING FOR THESE WINDS TO DIMINISH TO LESS THAN 20 KT BY 18 HOURS GULF OF FONSECA AND SIMILARLY GULF OF PAPAGAYO NEAR AT 36 HOURS. $$ AGUIRRE