000 AXPZ20 KNHC 110920 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC TUE DEC 11 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 08N78W TO 06N93W TO LOW PRES AT 10N102W 1009 MB. ITCZ AXIS EXTENDS FROM 05N110W TO 09N120W TO BEYOND 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM S OF MONSOON TROUGH AXIS E OF 85W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 60 NM EITHER SIDE OF ITCZ AXIS W OF 125W. ...DISCUSSION... E OF 110W... THE MAIN FORECAST ISSUE WILL BE THE DEVELOPMENT OF A GALE EVENT IN THE GULF OF TEHUANTEPEC BY LATE WED. A COLD FRONT EXTENDING FROM THE NE GULF OF MEXICO TO SOUTHERN VERACRUZ IS STALLING FOR THE MOMENT UNDER UNFAVORABLE SW FLOW ALOFT AHEAD OF A LONG WAVE TROUGH TO THE NW. NONETHELESS...THE VANGUARD OF COOLER AND DRIER AIR WILL MOVE IN THE GULF OF TEHUANTEPEC BY EARLY WED...WITH WINDS TO 20 KT. THIS WILL BE FOLLOWED BY A REINFORCING PUSH OVER THE GULF OF MEXICO ESTABLISHING A TIGHT PRES GRADIENT BETWEEN THE SW GULF OF MEXICO AND THE GULF OF TEHUANTEPEC BY LATE WED. WITH DENSER AIR PUSHING THROUGH THE CHIVELA PASS WED NIGHT...WINDS TO GALE FORCE CAN BE EXPECTED INTO THE GULF OF MEXICO FROM LATE WED THROUGH THU MORNING. LOOKING AHEAD...ANOTHER PULSE OF WINDS CAN BE EXPECTED THU NIGHT...BUT LIKELY JUST BELOW GALE FORCE AS THE AIRMASS N OF THE AREA WILL ALREADY BE MODIFYING AND SHIFTING EAST. WITH HIGH PRES BUILDING OVER THE GULF OF MEXICO THROUGH TODAY...PULSES OF FRESH WINDS WILL COMMENCE THROUGH THE GULF OF PAPAGAYO BY EARLY WED...WITH A STRONG PULSE EXPECTED THU NIGHT INTO MORNING AS HIGH PRES N OF THE AREA IS REINFORCED. SCATTERED MODERATE TO ISOLATED STRONG SHOWER AND THUNDERSTORM ACTIVITY IS NOTED ALONG THE MONSOON TROUGH S OF PANAMA E OF 85W AS A NEGATIVELY TILTED UPPER TROUGH SHIFTS EAST INTO CENTRAL AMERICA...INTERACTING WITH MODERATE CONVERGENCE NE AND SW BOUNDARY LAYER WINDS. GLOBAL MODEL CONSENSUS INDICATES A WEAK LOW PRES AREA WILL FORM ALONG THE MONSOON TROUGH BY TONIGHT OFF COSTA RICA DUE IN PART TO THE FIRST PULSE THROUGH PAPAGAYO...BUT THEN WEAKENING THROUGH MID WEEK AS UPPER SUPPORT DIMINISHES. STRONG CONVECTION IS PULSING NEAR A PERSISTENT 1009 MB LOW PRES CENTER NEAR 10N102W. THE CONVECTION HAS BEEN SUPPORTED BY DIVERGENCE ALOFT BETWEEN AN EXITING UPPER TROUGH AND AN ADVANCING RIDGE TO THE WEST ALONG 115W. WHILE THE CONVECTION HAS BEEN STRONG AT TIMES OVER THE PAST 24 HOURS...IT HAS LIKELY NOT BEEN CONSISTENT ENOUGH TO ALLOW THE LOW PRES TO DEEPEN MUCH IF AT ALL. UPPER SUPPORT WILL BE FLAGGING OVER THE NEXT 24 TO 48 HOURS...AS THE RIDGE FLATTENS DUE TO THE PUSH OF A VIGOROUS SHORT WAVE TROUGH N OF THE AREA INTO THE WATERS OFF SOUTHERN CALIFORNIA. W OF 110W... DEEP LAYER RIDGING CENTERED N OF THE AREA CONTINUES TO SHIFT W AS MID TO UPPER LEVEL SHORT WAVE TROUGHING CUTS ACROSS THE FAR NE PACIFIC. ANOTHER SHORT WAVE TROUGH IS DIGGING SOUTH ALONG THE CALIFORNIA COAST...INTO THE BASE OF A LONG WAVE TROUGH EXTENDING FROM THE NORTHERN PLAINS TO NORTHERN BAJA. A RELATED SURFACE TROUGH WILL PUSH SE THROUGH THE WATERS OFF NORTHERN BAJA E OF 125W THROUGH LATE TONIGHT. BY LATE WED...THE SHORT WAVE TROUGH CURRENTLY MOVING THROUGH THE NE PACIFIC WILL PUSH DOWN THE WEST COAST AND INTO THE WATERS OFF SOUTHERN CALIFORNIA...SUPPORTING THE PASSAGE OF A COLD FRONT INTO THE WATERS N OF 20N E OF 130W THU...THE WEAKENING AS IT MOVES FARTHER TO THE SE ALONG THE BAJA PENINSULA AND NORTHERN GULF OF CALIFORNIA. 1039 MB SURFACE HIGH PRES ASSOCIATED WITH THE DEEP LAYER RIDGE IS CENTERED NEAR 40N140W. SHIP AND SCATTEROMETER DATA INDICATE MAINLY MODERATE TO FRESH BREEZES N OF 20N W OF 120W S OF THE SURFACE HIGH PRES. FRESH NE SWELL PERSISTS N OF 20N W OF 130W. FARTHER SOUTH...THE AREA OF LINGERING FRESH TO STRONG TRADES IS SHRINKING FROM EAST TO WEST...AND IS CURRENTLY RELEGATED TO 15N TO 20N W OF 135W. LOW LEVEL CONVERGENCE OF THESE TRADES ALONG WITH REASONABLY HIGH PRECIPITABLE WATER VALUES S OF 15N ARE SUPPORTING SCATTERED MODERATE TO STRONG CONVECTION ALONG THE ITCZ. SE CROSS-EQUATORIAL SWELL PERSISTS S OF 04N BETWEEN 125W AND 132W...BUT GLOBAL WAVE MODELS SHOW THIS SWELL DECAYING BELOW 8 FT THROUGH THE NEXT 36 HOURS. $$ CHRISTENSEN