000 AXPZ20 KNHC 130945 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON AUG 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURE... THE EXPOSED CENTER OF MINIMAL TROPICAL STORM HECTOR IS AT 18.1N 111.4W AT 0900 UTC MOVING W OR 270 DEG AT 06 KT WITH MAXIMUM SUSTAINED WINDS OF 35 KT WITH GUSTS TO 45 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. HECTOR IS ENCOUNTERING STRONG EASTERLY SHEAR WITH SCATTERED MODERATE ISOLATED STRONG CONVECTION DISPLACED WELL W OF CENTER WITHIN 60 NM EITHER SIDE OF A LINE FROM 17N114W TO 20N119W. HECTOR IS EXPECTED TO CHANGE LITTLE AS IT STEERED WESTWARD WITH THE EASTERLY SHEAR CONTINUING AND ONLY A SLIGHT COOLING OF SURFACE WATERS FOR A DAY OR SO. IF HECTOR CAN MAINTAIN ITS CURRENT STRENGTH THAT LONG...IT IS EXPECTED TO WEAKEN TO A DEPRESSION ON WED. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A MONSOON TROUGH AXIS EXTENDS ALONG THE PACIFIC COAST OF CENTRAL AMERICA FROM COSTA RICA TO GUATEMALA NEAR 14N92W...THEN EXTENDS W OVER THE PACIFIC INTO A LOW LEVEL CYCLONE ANALYZED AT THE SURFACE AT 14N96.5W...WITH THE MONSOON TROUGH CONTINUING NW TO NEAR 15N105W WHERE IT LOSES IDENTITY IN THE BROAD CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL CYCLONE HECTOR AND INCREASING MONSOONAL FLOW. THE MONSOON TROUGH AXIS BECOMES DEFINED AGAIN NEAR 15N111W AND CONTINUES W TO NEAR 15N125W BEFORE TURNING SW TO BEYOND 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION EXTENDS ACROSS THE PACIFIC PARALLEL TO THE W COAST OF CENTRAL AMERICA...ROUGHLY WITHIN 150 NM EITHER SIDE OF A LINE FROM 05N77W TO 11N90W. SIMILAR CONVECTION IS NOTED WITHIN THE SW MONSOONAL FLOW IN THE AREA BOUNDED FROM 05N TO 15N BETWEEN 99W AND 116W. ...DISCUSSION... AN UPPER ANTICYLONE IS QUASI STATIONARY NEAR 29N126W WITH A WELL DEFINED UPPER RIDGE EXTENDING SW TO A SHARP CREST AT 28N138W. AN UPPER CYCLONE IS NOTED JUST N OF THE AREA AT 36N135W WITH AN UPPER TROUGH EXTENDING SW INTO THE DISCUSSION AREA FROM 32N138W TO 28N140W. A SECOND UPPER ANTICYLONE IS CENTERED OVER THE NORTHERN BAJA CALIFORNIA PENINSULA AT 28N114W WITH AN UPPER RIDGE EXTENDING SW TO A FAIRLY SHARP CREST AT 24N129W. BETWEEN THESE TWO ANTICYCLONES IS A SMALL UPPER CYCLONE STATIONARY AT 32N117W WITH A NARROW UPPER TROUGH EXTENDING SW ALONG 25N130W INTO ANOTHER SMALL UPPER CYCLONE THAT IS FILLING OVER THE DEEP TROPICS AT 14N135W. THESE UPPER FEATURES ALL COMBINE TO DRY OUT THE UPPER LEVELS OF THE DISCUSSION AREA N OF 22N W OF 109W...AND FROM 12N TO 22N BETWEEN 127W AND 140W. AN UPPER CYCLONE IS OVER E CENTRAL MEXICO AT 24N99W. THE ASSOCIATED UPPER DIFFLUENCE OVER ITS SE SEMICIRCLE IS ENHANCING SCATTERED STRONG CONVECTION WITHIN 30 NM OF MEXICAN COAST FROM 20N TO 24N. SOME OF THE DEBRIS MOISTURE FROM THIS CONVECTION AND CONVECTION ASSOCIATED WITH THE SURFACE LOW AT 14N96.5W IS NOW ADVECTED NE ACROSS MEXICO AND OVER THE SW GULF OF MEXICO. BROAD ANTICYCLONIC FLOW STILL DOMINATES THE UPPER LEVELS S OF 22N BETWEEN 105W AND 125W. THE DENSE DEBRIS MOISTURE FROM THE PREVIOUSLY DESCRIBED MONSOONAL CONVECTION...AND TROPICAL STORM HECTOR...IS ADVECTED SW CROSSING THE EQUATOR BETWEEN 110W AND 138W. THE SURFACE LOW ANALYZED NEAR 14N96.5W IS EXPECTED TO MOVE W TO NEAR 14N99W TONIGHT...THEN TURN NW REACHING NEAR 15N103W ON TUE NIGHT. SOME MODEL GUIDANCE IS VERY AGGRESSIVE AND SUGGESTS TROPICAL CYCLONE FORMATION...BUT A RECENT SCATTEROMETER PASS INDICATES THAT THE CYCLONIC CENTER IS ABOVE THE SURFACE. THEREFORE CURRENT MARINE FORECASTS...INCLUDING GRAPHICS...IS MUCH MORE CONSERVATIVE WITH THE DEVELOPMENT. THE ENVELOPE OF CYCLONIC 20 KT OR GREATER WINDS ASSOCIATED WITH TROPICAL STORM HECTOR IS EXPECTED TO SHRINK OVER THE NEXT FEW DAYS...BUT SOUTHERLY MONSOON FLOW AT 20 TO 25 KT TO THE S OF HECTOR IS EXPECTED TO EXPAND ACROSS THE AREA FROM ABOUT 05N TO 15N BETWEEN 95W AND 120W DURING THE NEXT COUPLE OF DAYS. GAP WINDS...NE WINDS AT 15 TO 20 KT ARE EXPECTED TO CONTINUE TO SURGE INTO AND JUST DOWNSTREAM OF THE GULF OF PAPAGAYO THROUGH MIDDAY WED BEFORE DIMINISHING. $$ NELSON