000 AXPZ20 KNHC 171532 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI AUG 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...TROPICAL WAVE... A TROPICAL WAVE WAS ALONG 95W N OF 14N OVER THE GULF OF TEHUANTEPEC. SCATTERED MODERATE CONVECTION WAS WITHIN 150 NM E OF THE WAVE N OF 14N CLOSE TO THE COAST OF MEXICO. THIS TROPICAL WAVE SHOULD FALL APART AS IT MOVES WESTWARD OVER THE HIGH TERRAIN OF SOUTHERN MEXICO TOMORROW. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 09N84W TO 09N92W THEN CONTINUES FROM 15N120W TO 10N140W. NUMEROUS MODERATE TO SCATTERED STRONG CONVECTION FROM 06N TO 08N BETWEEN 78W AND 81W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WITHIN 120 NM S OF TROUGH AXIS BETWEEN 81W AND 86W. SCATTERED MODERATE CONVECTION 90 TO 120 NM S OF TROUGH AXIS BETWEEN 125W AND 135W. ...DISCUSSION... LOW PRES 1006 MB NEAR 21.8N 116.8W...THE REMNANT LOW OF HECTOR...MOVING N-NW OR 335 DEG AT 05 KT. AN ASCAT PASS FROM AROUND 0530 UTC SHOWED SW WINDS 20 TO 25 KT WITHIN 180 NM IN THE SE QUADRANT OF THE LOW. THE LOW PRES IS SITUATED TO THE SW OF AN UPPER ANTICYCLONE CENTERED OVER NW MEXICO NEAR 28N111W...PROVIDING STEERING TOWARD THE NW ALONG WITH LIGHT SE SHEAR. CONVECTION HAS BEEN ALMOST NON-EXISTENT IN RELATION TO THIS LOW...ALTHOUGH A SMALL AREA OF MODERATE HAS RECENT FORMED WITHIN 60 NM OF THE CENTER IN THE SOUTH QUADRANT. THE LOW WILL SLOWLY FILL AS IT DRIFTS N THROUGH 48 HOURS. THE MAIN IMPACT OF THE REMNANT LOW OF HECTOR CONTINUES TO BE THE MOISTURE ADVECTING INTO SOUTHERN BAJA CALIFORNIA AND NW MEXICO IN THE SW FLOW. PRECIPITABLE WATER VALUES REMAIN VERY HIGH NEAR AND TO THE NE OF THE CENTER...WITH HEAVY PRECIPITATION BLANKETING THE AREA FROM BAJA CALIFORNIA SUR TO SONORA MEXICO INCLUDING THE GULF OF CALIFORNIA. FORTUNATELY THIS MOISTURE NOT ONLY SEEMS TO B STARTING TO TAPER OFF IN SSMI PW IMAGERY...BUT APPEARS TO BE PIVOTING TO THE NORTH AND AWAY FROM AREAS WHERE HEAVY RAINFALL HAS ALREADY OCCURRED SINCE YESTERDAY. HEAVY RAINS ARE STILL LIKELY NONETHELESS...PARTICULARLY OVER HIGH TERRAIN IN SONORA AND ACROSS BAJA CALIFORNIA THROUGH SAT. A MID TO UPPER LOW NEAR 38N135W WILL LIFT NNE TOWARD BRITISH COLUMBIA THROUGH 48 HOURS. MEANWHILE WEAK HIGH PRES 1018 MB CENTERED NEAR 29N129W TO THE NW OF THE REMNANT LOW OF HECTOR WILL BE OVER TAKEN BY LARGER SCALE RIDGING BUILDING INTO THE AREA FROM THE WEST...IN RESPONSE TO THE UPPER LOW NEAR 38N135W LIFTING TO THE NORTH. THE WEAKENED PRES PATTERN WILL MAINTAIN LIGHT TO MODERATE NE TRADE WIND FLOW W OF 120W THROUGH SUN. FURTHER SOUTH...SCATTEROMETER AND TOGA BUOY DATA OVER THE PREVIOUS 24 HOURS SHOW MODERATE TO FRESH S TO SW FLOW TO THE SOUTH OF THE MONSOON TROUGH POSITION...WITH ENOUGH LOW LEVEL CONVERGENCE TO MAINTAIN CLUSTERS OF MODERATE CONVECTION S OF THE MONSOON TROUGH AXIS. LOW PRES 1009 MB IS CENTERED NEAR 10N101W. THIS LOW HAS CHANGED LITTLE OVER THE PAST THREE DAYS AS IT DRIFTED SLOWLY W APPROXIMATELY 350 NM S OF THE GULF OF TEHUANTEPEC. GLOBAL MODEL SHOW THIS LOW WEAKENING SIGNIFICANTLY OR EVEN DISSIPATING AS IT CONTINUES TO MOVE W REACHING ROUGHLY 115W THROUGH 48 HOURS. A LARGE AREA OF CONVECTION IS ACTIVE OVER THE GULF OF PANAMA. THIS IS LARGELY DUE TO COMBINED EFFECTS OF ENHANCED SW MONSOON FLOW AND DIVERGENCE ALOFT ASSOCIATED WITH A WELL DEFINED UPPER CYCLONE CENTERED OVER THE SW CARIBBEAN JUST TO THE N OF PANAMA. GLOBAL MODEL CONSENSUS SHOWS THE UPPER CYCLONE WEAKENING AND OPENING UP INTO A TROUGH AS IT DRIFTS SLOWLY WEST. THIS SHOULD ALLOW CONVECTION TO DIMINISH THROUGH 48 HOURS. CROSS EQUATORIAL LONG PERIOD S SWELL HAS PROPAGATED ALONG THE ENTIRE PACIFIC COASTLINE WITHIN THE FORECAST AREA. THE PERIOD OF THIS SWELL REMAINS AROUND 16-18 SECONDS. SEAS TO 10 FT CAN CURRENTLY BE FOUND NEAR THE REMAINS OF HECTOR. SEAS WILL GRADUALLY SUBSIDE THROUGH TODAY. $$ CHRISTENSEN