000 AXPZ20 KNHC 151000 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED AUG 15 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 CENTER OF MINIMAL TROPICAL STORM HECTOR IS NEAR 17.2N 115.2W AT 0900 UTC DRIFTING W OR 270 DEG AT 02 KT WITH MAXIMUM SUSTAINED WINDS OF 35 KT WITH GUSTS TO 45 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. HECTOR CONTINUES TO EXPERIENCE EASTERLY SHEAR WITH SCATTERED STRONG CONVECTION OBSERVED WITHIN 120 NM OVER ONLY THE SW SEMICIRCLE. HECTOR IS EXPECTED TO CHANGE LITTLE AS IT STEERED SLOWLY WESTWARD TODAY WITH THE EASTERLY SHEAR CONTINUING AS THE SYSTEM MOVES ACROSS A GRADUAL COOLING OF SURFACE WATERS. HECTOR IS EXPECTED TO WEAKEN TO A DEPRESSION TONIGHT. 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 SW FROM EL SALVADOR TO A SMALL EMBEDDED LOW PRES AT 09N93W...THEN TURNS W TO 10N98W WHERE IT LOSES IDENTITY. THE MONSOON TROUGH AXIS BECOMES DEFINED AGAIN SW OF TROPICAL CYCLONE HECTOR NEAR 13N117W AND CONTINUES SW TO NEAR 09N138W WHERE LOW LEVEL CROSS EQUATORIAL SOUTHEASTERLY WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES W BEYOND 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM EITHER SIDE OF A LINE FROM 05N77W TO 07N98W. ISOLATED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 30 NM EITHER SIDE OF A LINE FROM 14.5N105W TO 11.5N115.5W TO 11.5N130W. ...DISCUSSION... AN DEEPENING UPPER CYCLONE IS NOTED JUST N OF THE AREA AT 34N131W WITH AN UPPER TROUGH EXTENDING SW INTO THE DISCUSSION AREA FROM 32N125W TO 20N130W TO A BASE AT 13N124W. A SURFACE LOW IS EXPECTED TO FORM N OF THE AREA AND TRAIL A WEAK COLD FRONT INTO THE NW WATERS ON THU WITH THE FRONT DISSIPATING ON FRI. IN THE MEANTIME...VERY DRY UPPER AIR IS ROTATING CYCLONICALLY N ACROSS MOST OF SOUTHERN CALIFORNIA WITH THE EXCEPTION OF THE EXTREME SE PORTION OF THE STATE WHERE THIN CIRRUS IN OBSERVED. AN UPPER ANTICYCLONE W OF AREA RIDGES E ALONG 25N TO A CREST AT 25N135W. A SECOND UPPER ANTICYLONE OVER SOUTHERN ARIZONA HAS AN UPPER RIDGE EXTENDING SW ACROSS THE CENTRAL NORTHERN BAJA CALIFORNIA PENINSULA TO A SHARP CREST AT 24N124W. UPPER DIFFLUENCE ENHANCED CONSIDERABLE CONVECTION OVER NEW MEXICO EARLIER AND CURRENTLY SCATTERED MODERATE TO STRONG CONVECTION CONTINUES IN THE GULF OF CALIFORNIA WITHIN 30 NM OF 29.5N113W. THE RESULTANT DENSE DEBRIS MOISTURE IS FANNING OUT OVER THE AREA N OF 27N BETWEEN 107W AND 115W...BEFORE TURNING E INTO A PLUME THAT CONTINUES E ACROSS TEXAS AND ARKANSAS BEFORE TURNING NE ACROSS THE APPALACHIANS. OTHERWISE THE UPPER LEVELS ARE DRY N OF 20N W OF 118W AND FROM 13N TO 20N W OF 121W. A SMALL UPPER CYCLONE HAS CUT OFF AT 23N120W WITH AN UPPER TROUGH EXTENDING SE ACROSS THE WESTERN PORTION OF TROPICAL CYCLONE HECTOR AND TURNING SE TO BASE AT 13N113W. AN UPPER ANTICYCLONE IS CENTERED OVER CENTRAL MEXICO AT 24N102W WITH A RIDGE CRESTING JUST N OF TS HECTOR AT 19N117W...AS IS CONTINUING TO STEER HECTOR W...BUT ALSO PROVIDING THE EASTERLY SHEAR INHIBITING HECTOR FROM INTENSIFYING. THE ENVELOPE OF UPPER ANTICYCLONIC FLOW EXTENDS S OVER THE PACIFIC ADVECTING CONVECTIVE DEBRIS MOISTURE SW BETWEEN 100W AND 110W. AN UPPER TROUGH THAT EXTENDS SW ACROSS THE EASTERN CONUS CONTINUES SW ACROSS THE GULF OF MEXICO INTO AN TROPICAL UPPER CYCLONE OVER THE PACIFIC AT 12N93W...WITH THE TROUGH CONTINUING S TO BASE AT 07N92W. UPPER DIFFLUENCE E OF THE UPPER TROPICAL CYCLONE IS ENHANCING SCATTERED MODERATE TO STRONG CONVECTION WITHIN 30 NM OF CENTRAL AMERICAN COAST FROM 11N TO 14N...AND ALONG THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED. THE DEBRIS MOISTURE IS SPREADING S TO THE EQUATOR BETWEEN 90W AND 100W... AND IS ALSO SPREADING N ACROSS CENTRAL AMERICA BETWEEN 80W AND 90W. THE ENVELOPE OF CYCLONIC 20 KT OR GREATER WINDS ASSOCIATED WITH TROPICAL STORM HECTOR EXTENDS ONLY ABOUT 90 NM OVER THE N SEMICIRCLE...BUT EXTENDS ABOUT 480 NM OVER THE S SEMICIRCLE MOSTLY DUE TO STRONG SOUTHWESTERLY MONSOONAL FLOW. LONG PERIOD SW SWELLS ARE NOTED OVER THE AREA S OF 21N BETWEEN 97W AND 119W AND ALSO S OF 09N BETWEEN 82W AND 87W...WITH THE SWELL TRAIN INTERRUPTED BY THE GALAPAGOS ISLANDS. THESE SWELLS ARE EXPECTED TO SUBSIDE OVER THE NEXT COUPLE OF DAYS. $$ NELSON