000 AXPZ20 KNHC 010332 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE DEC 01 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...ITCZ... AXIS ANALYZED ALONG 07N78W TO 07N100W TO 08N113W TO 12N129W TO 09N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WAS WITHIN 120 NM S OF THE AXIS BETWEEN 80W AND 82W AND WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 112W AND 114W. SCATTERED MODERATE CONVECTION WAS BETWEEN 91W AND 95W...AND ALSO W OF 134W. ...DISCUSSION... AN AMPLIFIED OMEGA BLOCK PATTERN REMAINS IN PLACE OVER THE DISCUSSION AREA. A LARGE MID TO UPPER LEVEL RIDGE REMAINS THE DOMINANT FEATURE OVER THE DISCUSSION AREA W OF 125W. 1025 MB HIGH PRES IS CENTERED NEAR 42N131W WITH A RIDGE AXIS EXTENDING SE INTO THE BASIN TO 18N113W. THE TIGHT RIDGE IS RESULTING IN NE TRADE WINDS W OF 112W IN THE 20 TO 25 KT RANGE. THE RIDGE WILL WEAKEN DURING THE NEXT 48 HOURS WITH THE HIGH PRES CENTER SHIFTING OFF TO THE NE AS A COLD FRONT APPROACHES THE NW CORNER OF THE BASIN. THE STRONGEST WINDS ASSOCIATED WITH THIS FRONT WILL REMAIN N AND W OF THE DISCUSSION AREA. ALSO...AS THE RIDGE WEAKENS OVER OUR AREA...THE AREA OF STRONG TRADES WILL DIMINISH IN STRENGTH AND COVERAGE DURING THE NEXT 48 HOURS. ANOTHER EPISODE OF LARGE LONG PERIOD NW SWELLS WILL SPREAD SE FOLLOWING THE COLD FRONTAL PASSAGE TO THE N LATE IN THE FORECAST PERIOD. A LONGWAVE UPPER TROUGH AND ATTENDANT COLD FRONT IS APPROACHING THE AREA WITH THE LEADING EDGE OF THIS FEATURE NOW AT 30N140W... BUT IT WILL WEAKEN AS IT ENCOUNTERS THE RIDGE WITH THE MAJORITY OF ANY ASSOCIATED ENERGY AND MOISTURE REMAINING N OF 32N. ANOTHER UPPER TROUGH EXTENDS OVER THE NE PORTION OF THE AREA ON THE FRONT/E SIDE OF THE RIDGE EXTENDING FROM S CENTRAL TEXAS TO JUST SE OF THE SOUTHERN TIP OF THE BAJA PENINSULA TO 21N114W... WITH VERY DRY AND STABLE AIR IN PLACE N OF THE TROUGH. A JET CORE WITH SATELLITE DERIVED WINDS OF 120-130 KT ALONG THIS TROUGH AXIS EXTENDS FROM CENTRAL MEXICO TO ALONG THE U.S. GULF OF MEXICO COAST...WHICH WAS ADVECTING A LARGE PLUME OF TROPICAL MOISTURE ACROSS CENTRAL MEXICO WHICH IS FEEDING INTO A FRONTAL BOUNDARY NOW OVER THE NW GULF OF MEXICO. A LARGE UPPER LEVEL LOW CENTERED NEAR 32N109W HAS CUT OFF FROM THE MAIN FLOW PATTERN AND CONTINUES TO DRIFT TO THE E ALONG THE U.S./MEXICO BORDER. SURFACE LOW PRES OF 1008 MB IS FUNNELING 20 TO 25 KT NW TO N WINDS INTO THE N GULF OF CALIFORNIA...AS CAPTURED BY A 1758 UTC ASCAT PASS. A 1722 UTC JASON ALTIMETER PASS INDICATED 8 FT SEAS N OF 29N IN THE GULF OF CALIFORNIA... ALTHOUGH THE RELIABILITY OF THIS DATA IS SOMEWHAT QUESTIONABLE GIVEN ITS PROXIMITY TO LAND FEATURES. THE SURFACE LOW WILL MOVE QUICKLY TO THE NE EFFECTIVELY DIMINISHING WINDS BELOW 20 KT BY LATE TUE. MODEL SOLUTIONS DIVERGE WITH REGARD TO THEIR HANDLING OF A COMPLEX SURFACE AREA OF LOW PRES W OF 130W WITH THE GFS STILL SUPPORTING AN INTENSIFYING MAINLY TROPICAL VORTICITY MAXIMUM TO WELL W OF THE AREA...WHILE SPINNING GALE FORCE WINDS W OF 130W. THIS OUTLIER SOLUTION IS LIKELY DUE TO THE CONVECTIVE FEEDBACK PROBLEM INHERENT IN THE GFS MODEL. THE ECMWF...NAM AND NOGAPS SOLUTIONS DIFFER SIGNIFICANTLY AND APPEAR TO BE MORE REASONABLE AND CONSISTENT...THUS WILL LEAN THE FORECAST TOWARD A CONSENSUS OF THOSE MODELS. ELSEWHERE AT THE SURFACE...A WEAK SURFACE TROUGH...WHICH IS THE REMNANTS OF PREVIOUS LOW PRES...ALONG 111W CONTINUES TO WEAKEN AS IT ENCOUNTERS HOSTILE SW SHEAR AND VERY DRY AIR ALOFT. AN EARLIER 1624 UTC ASCAT PASS AND REPORTS FROM NEARBY BUOYS CONTINUED TO INDICATE E TO SE WINDS OF 20 TO 25 KT IN THE LEE OF THE TROUGH. THIS FEATURE IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS WHILE SEAS TO 9 FT CONTINUE IN LARGE LONG PERIOD NW SWELLS. ...GAP WINDS... EASTERLY TRADE WINDS ACROSS THE SW CARIBBEAN CONTINUE TO FUNNEL WINDS THROUGH GULF OF PAPAGAYO AND DOWNSTREAM WATERS TO 89W THROUGH TUE EVENING...THEN WILL DIMINISH TO LESS THAN 20 KT AS THE TRADES EASE. $$ LEWITSKY