000 AXPZ20 KNHC 040307 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT AUG 04 2012 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0045 UTC. ...TROPICAL WAVES... THE SOUTHERN END OF A TROPICAL WAVE OVER GUATEMALA CURRENTLY LIES ALONG 91W N OF 10N AND IS MOVING W AROUND 10-15 KT. WINDS ARE CURRENTLY A GENTLE BREEZE OR LESS NEAR THE WAVE. CONVECTION HAS WANED NEAR THE WAVE...WITH ONLY ISOLATED MODERATE CONVECTION NOTED ON ITS SOUTHERN END NEAR THE MONSOON TROUGH FROM 06N TO 09N BETWEEN 88W AND 92W. HOWEVER...PRECIPITABLE WATER VALUES ARE INCREASING IN THIS AREA OF CONVECTION AND THE 20 KT EASTERLY SHEAR OVER THE REGION IS EXPECTED TO WEAKEN OVER THE NEXT 12-24 HOURS. A TROPICAL WAVE LIES ALONG 105W FROM 09N TO 17N. THE WAVE IS MOVING W AROUND 5-10 KT. SCATTERED MODERATE CONVECTION WAS FROM 07N TO 11N BETWEEN 101W AND 109W...IN THE REGION CLOSEST TO THE MONSOON TROUGH. WINDS ARE ONLY AS STRONG AS A MODERATE BREEZE WITH THIS WAVE. THE 1608 UTC ASCAT PASS SUGGESTED THAT THE WAVE IS BECOMING POORLY DEFINED AT THE SURFACE. A TROPICAL WAVE STRETCHES FROM 17N121W TO 11N123W AND IS MOVING W AROUND 10 KT. SCATTERED MODERATE CONVECTION WAS NOTED FROM 11N TO 17N BETWEEN 117W AND 124W WHERE THE WAVE CROSSES A RIDGE AXIS ALOFT THAT EXTENDS BETWEEN UPPER ANTICYCLONES CENTERED NEAR 14N112W AND 12N129W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS FROM 06N TO 11N BETWEEN 115W AND 120W...IN THE MORE STRONGLY DIFFLUENT REGION BETWEEN THE RIDGE AND AN UPPER LOW CENTERED ON THE EQUATOR NEAR 115W. THE PRECIPITABLE WATER VALUES ARE HIGHER NEAR THIS WAVE THAN ANYWHERE ELSE IN THE FORECAST AREA. CONVECTION IS EXPECTED TO CONTINUE WITH THIS SYSTEM OVER THE NEXT DAY OR SO. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS 10N84W TO 09N89W TO 12N99W TO 09N111W TO 13N119W TO 10N127W. ITCZ AXIS FROM 10N127W TO 09N127W. SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 90 NM S OF THE AXIS E OF 85W. SCATTERED MODERATE CONVECTION WAS WITHIN 60 NM N AND 120 NM S OF THE AXIS BETWEEN 109W AND 114W AS WELL AS WITHIN 120 NM N AND 180 NM S OF THE AXIS W OF 124W. ...DISCUSSION... THE 1032 MB SUBTROPICAL HIGH NEAR 42N143W IS FORECAST TO WEAKEN AS IT CONTINUES MOVING W OVER THE NEXT TWO DAYS...WEAKENING THE RIDGING OVER THE FORECAST AREA. THE BELT OF FRESH TO STRONG TRADE WINDS N OF THE ITCZ AND W OF 135W HAS DIMINISHED TO 20 KT OR LESS OVER THE LAST 6 HOURS ACCORDING TO THE 1928 UTC ASCAT PASS. NE SWELL WILL KEEP SEAS AT 8-9 FT IN THIS AREA THROUGH MIDDAY SUN. A STRONG SOUTH PACIFIC SUBTROPICAL RIDGE IS CURRENTLY IN PLACE AND IS FORCING A MODERATE TO FRESH SE BREEZE S OF THE MONSOON TROUGH WITH THE STRONGEST WINDS FOUND S OF 06N BETWEEN 110W AND 120W ACCORDING TO THE 1750 UTC ASCAT PASS. CROSS-EQUATORIAL SOUTHERLY SWELL HAS REACHED THE COAST OF PANAMA AND COSTA RICA AS WELL AS FAR SOUTHERN MEXICO AND HAS MOVED AS FAR N AS 17N IN WATERS BETWEEN THE GALAPAGOS ISLANDS AND 125W. THE LEADING EDGE OF THIS SWELL HAS PERIODS IN EXCESS OF 20 SECONDS. IT WILL MOVE NORTHWARD ALONG THE CENTRAL AMERICAN AND MEXICAN COAST TONIGHT AND INTO THE SOUTHERN GULF OF CALIFORNIA AND THE PACIFIC COAST OF BAJA CALIFORNIA ON SAT BEFORE MAKING ITS WAY N ONTO THE CALIFORNIA COAST. INTERESTS ALONG THE COAST SHOULD BE AWARE OF THE POTENTIAL FOR HIGH SURF AND POSSIBLY SOME COMPLICATIONS ENTERING HARBORS AND INLETS. SWELL HEIGHTS TO 9 FT CAN BE EXPECTED AS FAR N AS 10N THROUGH SUN AFTERNOON. A SERIES OF WEAK ANTICYCLONES ALOFT CAN BE FOUND AT 14N98W... 14N112W AND 12N129W. UPPER DIFFLUENCE ALONG THE RIDGE AXIS STRINGING THESE ANTICYCLONES TOGETHER IS ENHANCING CONVECTION NEAR THE TROPICAL WAVES ALONG 105W AND NEAR 122W. THE WESTERN ANTICYCLONE IS ASSOCIATED WITH A BROAD REGION OF UPPER DIFFLUENCE ON ITS SOUTHERN EDGE WHICH LIES OVER AN AREA OF PLENTIFUL LOW LEVEL MOSITURE CONVERGED NEAR THE ITCZ W OF 124W. THE CONVECTION ALONG THIS WESTERN EDGE OF THE MONSOON TROUGH/ITCZ AXIS IS DESCRIBED IN THE SECTION ABOVE. THE AXIS SHOULD REMAIN ACTIVE HERE OVER THE NEXT FEW DAYS AS THESE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO SEE LITTLE CHANGE. THE SURFACE PRESSURE GRADIENT WILL INCREASE IN THE EVENING HOURS ALONG THE PACIFIC COAST OF BAJA CALIFORNIA OVER THE NEXT FEW DAYS AS DIURNALLY LOWER PRESSURE OVER MAINLAND MEXICO BUTTS UP AGAINST THE SUBTROPICAL RIDGE. THIS WILL BRIEFLY INCREASE THE WINDS TO A FRESH BREEZE IN THE REGION EACH EVENING. $$ SCHAUER