000 AXPZ20 KNHC 142149 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN JUL 14 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...TROPICAL LOW AND WAVES... A 1011 MB SURFACE LOW PRESSURE IS CENTERED NEAR 18N106W WITH ISOLATED MODERATE TO OCCASIONALLY STRONG STRONG CONVECTION OBSERVED WITHIN 120 NM NW AND WITHIN 360 NM S QUADRANTS OF CENTER. GUIDANCE DOES NOT MAINTAIN A CIRCULATION FOR 24 HOURS AND THIS LOW IS EXPECTED TO WEAKEN TO AN OPEN TROUGH EARLY MON AND DISSIPATE BY TUE. A TROPICAL WAVE IS ANALYZED TO THE N OF 10N ALONG 96W AND IS ACCOMPANIED BY SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WITHIN 60 NM OF 13N96W AND 16N98W. ONLY A NE-E-SE 10-15 KT WIND SHIFT IS EXPECTED ALONG THE WAVE AXIS AS IT CONTINUES WESTWARD AT ABOUT 12 KT. ALTHOUGH GUIDANCE DAMPENS THE WAVE IT HANGS ONTO THE DESCRIBED WIND SHIFT ALONG ITS AXIS THROUGH NEXT WEEKEND WITH THE WAVE AXIS REACHING ALONG 120W ON SAT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS W FROM THE COAST OF COLOMBIA AT 08N81W TO ACROSS THE SOUTHERN TIP OF PANAMA...THEN TURNS NW TO 12N106W...THE W TO 12.5N125W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN INTERTROPICAL CONVERGENCE ZONE. THE ITCZ THEN CONTINUES W TO 12N132W...THEN TURNS SW TO BEYOND 10N140W. ISOLATED MODERATE TO STRONG CONVECTION IS NOTED TO THE S OF THE EASTERN PORTION OF THE MONSOON TROUGH...WITHIN 30 NM EITHER SIDE OF LINES FROM 06N77W TO 09N101W AND FROM 14N104W TO 09N116W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ALONG THE WESTERN PORTION OF THE MONSOON TROUGH WITHIN 60 NM OF 08N139W. SIMILAR CONVECTION IS OBSERVED ALONG THE ITCZ WITHIN 120 NM EITHER SIDE OF A LINE FROM 13N121W TO 11.5N137W. ...DISCUSSION... AN UPPER ANTICYCLONE IS AT 23N133W WITH AN UPPER RIDGE EXTENDING NE TO 28N124W AND A RIDGE EXTENDING SW TO BEYOND 23N140W. ANOTHER SMALL UPPER ANTICYCLONE IS NOTED AT 21N126W. A THIRD UPPER ANTICYCLONE IS AT 17N132W AND IS ADVECTING DEBRIS MOISTURE FROM THE ITCZ NORTHWARD TO ALONG 20N BETWEEN 132W-140W. OTHERWISE...THESE UPPER LEVEL FEATURES COMBINE TO DRY OUT THE UPPER LEVELS OF THE DISCUSSION AREA TO THE N OF 17N W OF 121W. AN UPPER CYCLONE IS QUASI-STATIONARY OVER THE DEEP TROPICS NEAR 07N128W WITH AN UPPER TROUGH EXTENDING SW TO BEYOND 04N140W. THE UPPER FLOW IS SLIGHTLY DIFFLUENT BETWEEN THE PREVIOUSLY MENTIONED TROPICAL UPPER RIDGE AND THIS TROPICAL UPPER TROUGH...AND IS ENHANCING THE CONVECTION PREVIOUSLY DESCRIBED ALONG THE ITCZ. A WELL-DEFINED UPPER CYCLONE IS CENTERED AT 18N115W WITH AN UPPER TROUGH EXTENDING N TO A SHARP CREST AT 28N120W. AN UPPER RIDGE ALSO EXTENDS SE TO 16N107W. THIS UPPER CYCLONIC CIRCULATION IS PULLING DEBRIS MOISTURE...FROM PREVIOUS CONVECTION ALONG THE SIERRA MADRE OCCIDENTAL...W ACROSS THE GULF OF CALIFORNIA AND THE BAJA CALIFORNIA PENINSULA TO OVER THE PACIFIC REMAINING TRAPPED WITH THE UPPER TROUGH WITH THE WESTERN BOUNDARY OF THE MOISTURE EXTENDING N TO S ALONG 121W FROM 20N-31N. AN UPPER TROUGH IS AMPLIFYING S ACROSS THE GULF OF MEXICO WITH ITS BASE WELL DEFINED BY A 90 NM WIDE BAND OF DRY AIR...ROUGHLY ALONG 19N95W TO 20N103W THEN NW TO 30N112W. CONVECTION IS BEGINNING TO FLARE OVER S OF 20N OVER MEXICO JUST AHEAD OF THIS DRY BOUNDARY...AND WOULD EXPECT THESE SMALL CLUSTERS OF CONVECTION TO SHIFT S AND BEGIN TO FLARE WITHIN THE NEXT FEW HOURS ALONG THE PACIFIC COAST OF MEXICO BETWEEN GUATEMALA AND 20N. AN UPPER ANTICYCLONE IS CENTERED OVER GUATEMALA WITH ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING S OF THE TROPICAL PACIFIC ALONG 06N BETWEEN 83W-98W...AND PROVIDING JUST ENOUGH UPPER DIFFLUENCE ALONG ITS PERIPHERY TO SUPPORT THE CONVECTION PREVIOUSLY DESCRIBED ALONG THE MONSOON TROUGH AND NEAR THE TROPICAL WAVE. THE DEBRIS MOISTURE SEEMS TO EVAPORATE WITHIN A FEW HUNDRED MILES OF THE CLUSTERS. AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N138W TO 13N108W. NE TRADES AT 15-20 KT ARE OBSERVED ACROSS THE TROPICS FROM 11N-18N W OF 132W WITH SEAS OF 5-7 FT IN MIXING NE AND SE SWELL. THE GRADIENT WILL RELAX ON MON WITH THE TRADES DIMINISHING TO 15 KT MON NIGHT. THE GRADIENT WILL STRENGTHEN AGAIN ON TUE WITH TRADES AT 15-20 KT S OF THE RIDGE. NW WINDS CURRENTLY AT 5-10 KT WILL PERSIST THROUGH EARLY TUE ALONG THE WESTERN SHORE OF THE BAJA CALIFORNIA PENINSULA THEN INCREASE TO NW AT 15 KT ON TUE NIGHT ACROSS THE WATERS TO THE N OF 28N. NW WINDS OF 15-20 KT ARE EXPECTED N OF 25N W OF THE BAJA PENINSULA TO 122W ON THU WITH SEAS TO 7 FT. GULF OF PAPAGAYO...NE WINDS WILL INCREASE BRIEFLY TO 15-20 KT LATE EACH NIGHT AND CONTINUE UNTIL AFTER SUNRISE EACH MORNING THROUGH THE END OF THE WEEK. S SWELLS RESULTING IN COMBINED SEAS TO 8 FT WILL ARRIVE ALONG THE EQUATOR BETWEEN 115W-128W ON MON NIGHT. THESE CONDITIONS WILL REACH ALONG 06N BETWEEN 100W-115W ON WED THEN BEGIN TO SUBSIDE. THE LONG PERIOD SW SWELL ENERGY WILL REACH THE COAST OF CENTRAL AMERICA LATE IN THE WEEK. $$ NELSON