000 AXPZ20 KNHC 120959 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED DEC 12 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 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 07N78W TO 09N85W TO 06N95W TO LOW PRES NEAR 10N103W 1011 MB. ITCZ AXIS EXTENDS FROM 07N108W TO BEYOND 07N140W. SCATTERED MODERATE CONVECTION WITHIN 30 NM EITHER SIDE OF MONSOON TROUGH AXIS E OF 83W. SCATTERED MODERATE CONVECTION WITHIN 120 NM N OF ITCZ BETWEEN 125W AND 135W. ...DISCUSSION... E OF 110W... MAIN ISSUE REMAINS DEVELOPMENT OF GALE FORCE WINDS THROUGH THE GULF OF TEHUANTEPEC BY LATE TODAY. A STALLED FRONT OVER THE GULF OF MEXICO WILL RECEIVE A REINFORCING SHOVE FROM AN UPPER TROUGH CURRENTLY DIGGING THROUGH THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY. THE RESULTANT MOVEMENT OF COOLER AND DRIER AIR INTO THE WESTERN GULF OF MEXICO ALONG WITH A TIGHTENING OF THE PRES GRADIENT WILL ALLOW FRESH TO STRONG WINDS TO COMMENCE THROUGH THE ISTHMUS AND INTO THE GULF OF TEHUANTEPEC BY THIS AFTERNOON...INCREASING TO GALE FORCE BY EVENING. THE PROGRESSIVE NATURE OF THE PATTERN WILL ALLOW THE AIRMASS N OF THE AREA TO SHIFT EAST...TEMPERING GALE FORCE CONDITIONS THROUGH THU. ANOTHER SHOT OF NEAR GALE FORCE WINDS CAN BE EXPECTED THU NIGHT INTO FRI MORNING WITH THE AID OF LOCALIZED OVERNIGHT DRAINAGE EFFECTS. FOR SAT AND BEYOND...THE PRES GRADIENT WILL WEAKEN WITH MODERATE TO FRESH BREEZES PREVAILING IN THE EARLY MORNING HOURS. HIGH PRES BUILDING OVER THE GULF OF MEXICO WILL ALLOW GAP WIND FLOW TO BRIEFLY PULSE AS WELL AS HIGH AS 25 KT WED NIGHT INTO THU MORNING...AND THU NIGHT INTO FRI MORNING. A WINDSAT PASS FROM AROUND 01 UTC INDICATED A WEAK CIRCULATION PERSISTS ALONG THE MONSOON TROUGH NEAR 10N103W...WITH AN ESTIMATED PRES AROUND 1011 MB. THIS LOW HAS LOST ITS UPPER SUPPORT AND CONVECTION HAS PRETTY MUCH DISSIPATED. GLOBAL MODELS INDICATE THIS WILL OPEN UP INTO A TROUGH TODAY...THEN FLATTEN OUT INTO FRI. W OF 110W... AN UPPER DISTURBANCE IS WELL DEFINED ON SATELLITE IMAGERY PUSHING SE ALONG THE WEST COAST OF THE U.S...ASSOCIATED COLD FRONT WILL PUSH S OF 32N TODAY AND REACH FROM SOUTHERN CALIFORNIA TO 25N130W BY THIS EVENING. THE UPPER TROUGH WILL CUT OFF THROUGH LATE THU AS IT SWINGS ACROSS SOUTHERN CALIFORNIA AND NORTHERN BAJA...WITH THE COLD FRONT EXTENDING FROM NORTHERN BAJA TO 22N120W. GLOBAL MODELS ARE IN DECENT AGREEMENT WITH THE PLACEMENT AND MOVEMENT OF THE UPPER TROUGH...WITH THE GFS SLIGHTLY SLOWER THAN THE OTHER MODELS. STRONG DEEP LAYER RIDGE REMAINS ALONG 150W WITH 1038 SURFACE HIGH PRES CENTERED NEAR 40N150W. THIS IS MAINTAINING FRESH TO STRONG TRADES N OF 25N W OF 135W...FARTHER SOUTH FROM 15N TO 18N W OF 135W. REINFORCING N TO NE WINDS WILL PREVAIL OVER MUCH OF THE AREA N OF 15N W OF 130W AS THE HIGH PRES SAGS SE BEHIND THE COLD FRONT...WITH SEAS 8 TO 10 FT MAINLY N OF 25N BEHIND THE FRONT. LOOKING AHEAD TO SAT AND SUN...DYNAMIC AND ENSEMBLE MODELS ARE IN DECENT AGREEMENT SHOWING A SECOND UPPER TROUGH CURRENTLY OVER THE ALEUTIANS FOLLOWING BEHIND THE FIRST TROUGH AND DIGGING SE INTO SOUTHERN CALIFORNIA AND NORTHERN BAJA. ECMWF AND UKMET IN GOOD AGREEMENT TRENDING A LITTLE MORE QUICKLY THAN EARLIER RUNS. ALTHOUGH THERE REMAINS SOME DISAGREEMENT WITH REGARD TO EXACT TIMING AND PLACEMENT...GENERAL CONSENSUS INDICATES A SURFACE LOW PRES AREA WILL FORM OFF SOUTHERN CALIFORNIA AND NORTHERN BAJA BY EARLY SAT...N OF ELONGATED SURFACE RIDGING ALONG 27N...WITH SOME POTENTIAL FOR FRESH TO STRONG W TO NW WINDS N OF 28N E OF 125W BY LATE SAT. GULF OF CALIFORNIA...SW WINDS WILL INCREASE BY LATE THU OVER THE FAR NORTHERN GULF AHEAD OF A COLD FRONT PUSHING INTO THE AREA. THE WINDS WILL PERSIST INTO FRI BEFORE VEERING NW AND GRADUALLY DIMINISHING THROUGH SAT. $$ CHRISTENSEN