000 AXPZ20 KNHC 041526 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED DEC 04 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1430 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH FROM 7N77W TO 6N81W TO 9N89W TO 7N99W THEN ITCZ ALONG 8N113W TO A 1009 MB LOW 9N125W TO 5N133W TO BEYOND 6N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-11N BETWEEN 120W-124W...WITHIN 60 NM N OF AXIS FROM 115W-117W...AND FROM 11N-13N BETWEEN 116W-120W. ...DISCUSSION... WEAK UPPER LEVEL TROUGH EXTENDS FROM 28N123W S TO 18N126W. VERY DRY STABLE AIR MASS W OF UPPER TROUGH BUT MOISTURE APPROACHING THE NW CORNER OF BASIN ON TOP OF RIDGE CREST NOW ALONG 140W. DOWNSTREAM OF TROUGH...A 90 KT JETSTREAM ADVECTS ABUNDANT MOISTURE FROM THE TROUGH AXIS TO OVER BAJA CALIFORNIA... NORTHERN MEXICO AND TEXAS FEEDING A DEVELOPING LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA AND ITS ASSOCIATED FRONTAL BOUNDARY. LARGE MID TO UPPER LEVEL ANTICYCLONE OVER SOUTHERN MEXICO AT 18N93W CONTRIBUTES CONVECTIVE DEBRIS MOISTURE FROM THE CONVECTION DESCRIBED ABOVE. OTHERWISE...RIDGE CAPS VERY DRY AIR MASS OVER BASIN S OF 20N E OF 110W. ...ELSEWHERE AT THE LOWER LEVELS... A WEAKENING SURFACE TROUGH EXTENDS FROM 24N133W TO 18N134W. A TIGHT PRESSURE GRADIENT WITH HIGH PRESSURE N OF AREA BRINGING FRESH NE TRADES N OF 22N W OF 133W. SURFACE TROUGH IS EXPECTED TO SHIFT NE DIMINISHING TRADES TO A MODERATE NE BREEZE. BUT THIS WILL ALLOW VIGOROUS HIGH PRES TO MOVE OVER NORTHERN PART OF BASIN BRINGING STRONG NE-E WINDS BACK AGAIN N OF 20N W OF 125W. WEAK TROUGH HAS DISSIPATED WITH FRESH E-SE BREEZE AND 8 FT SEAS REMAINING 10N TO 12N BETWEEN 116W AND 119W THROUGH TONIGHT. $$ PAW