000 AXPZ20 KNHC 040328 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN DEC 04 2011 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0330 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 08N78W TO 06N92W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N92W TO LOW PRES NEAR 09N105W TO 06N112W TO WEAK LOW PRES 1011 MB NEAR 10N120W TO 09N130W TO 08N140W. SCATTERED MODERATE WITHIN 60-90 NM OF ITCZ W OF 138W. ...DISCUSSION... A SHARP UPPER LEVEL TROUGH EXTENDS FROM A WELL DEFINED MID TO UPPER LEVEL CYCLONE OVER WEST CENTRAL ARIZONA NEAR 34N113W SW OVER THE NORTHERN BAJA INTO THE PACIFIC WATERS TO A BASE NEAR 20N120W. REINFORCING SHORTWAVE ENERGY IS ROUNDING THE BASE OF THE UPPER LEVEL TROUGH AND HAS BECOME ABSORBED INTO THE DEEP LAYERED CYCLONE NOTED ABOVE. THE SW EXTENSION OF THE SHORTWAVE WAS INSTRUMENTAL IN BROADENING THE TROUGH BASE OVER THE AREA N OF 20N E OF 130W. WATER VAPOR IMAGERY INDICATES VERY DRY AIR AND RELATIVELY STABLE CONDITIONS ALOFT WITH THIS UPPER LEVEL FEATURE. ELSEWHERE BROAD UPPER LEVEL RIDGES ARE FOUND BOTH TO THE W AND SE OF THE UPPER LEVEL TROUGHING...ONE WITH AN AXIS ALONG 135W AND THE OTHER CENTERED IN THE DEEP TROPICS NEAR 04N93W EXTENDING N-NE ACROSS MUCH OF CENTRAL AMERICA...SOUTHERN MEXICO AND OVER THE GULF OF MEXICO. HIGH PRESSURE IS FORECAST TO BUILD INTO THE SOUTHWEST CONUS ACROSS THE GULF OF CALIFORNIA REGION FROM THE N TONIGHT INTO SUNDAY AND PRODUCE FRESH TO LOCALLY STRONG NORTHERLY WINDS PERSISTING THROUGH THE NEXT 48 HOURS. A SECOND AND STRONGER SURGE OF NW WINDS IS EXPECTED TUE AND WED WITH WINDS POSSIBLY REACHING GALE FORCE. HIGH PRESSURE WELL N OF THE AREA ACROSS THE FAR EASTERN NORTH PACIFIC EXTENDS S TO 18N BETWEEN 125W-150W ACROSS WESTERN PORTIONS OF THE DISCUSSION AREA...AND IS MAINTAINING FRESH NELY WINDS GENERALLY W OF 125W SOUTHWARD TO THE ITCZ ALONG ABOUT 08N. THIS WAS CONFIRMED BY AN EARLIER 1836 UTC ASCAT PASS AND A FEW SHIP OBSERVATIONS. SEAS OF 8 TO 12 FT PREVAIL ACROSS THIS AREA IN A MIX OF N AND NEW NW SWELL...AND BUILDING NE WIND WAVES. THIS WIND FLOW WILL DIMINISH AND VEER MORE NE TO E THROUGH 48 HOURS BUT EXPAND EASTWARD BETWEEN 12N AND 20N TO ALONG 115W OR SO AS HIGH PRES N OF THE AREA WEAKENS SLIGHTLY AND DRIFTS E. TO THE SE...A 1011 MB LOW PRES CENTER REMAINS EMBEDDED WITHIN THE ITCZ NEAR 09N105W WAS MOVING WNW AT 10 KT. AN EARLIER ASCAT PASS FROM 1656 UTC INDICATED 20 TO 25 KT WINDS WITHIN 150 NM ACROSS THE NRN SEMICIRCLE OF THE LOW PRES. GLOBAL MODELS SUGGEST SOME INCREASE IN SOUTHERLY FLOW INTO THE LOW OVER THE NEXT 48 HOURS... WITH THE LOW PERSISTING AT LEAST THROUGH 72 HOURS AS IT SHIFTS WNW AT AROUND 10 KT. THIS IS PLAUSIBLE THROUGH 48 HOURS GIVEN THAT THE LOW WILL MOVE INTO INTO THE FAVORABLE SE PORTION OF A BROAD UPPER LEVEL TROUGH TO THE N. THE UPPER LEVEL TROUGH AMPLIFIES BEYOND THAT...WITH THE LOW LIKELY WEAKENING. A LACK OF DEEP LAYER MOISTURE IS PREVENTING ANY MAJOR CONVECTIVE ACTIVITY NEAR THIS LOW PRES AREA PRESENTLY. GULF OF TEHUANTEPEC...ALTHOUGH THERE WERE NO SCATTEROMETER PASSES SAMPLING THE REGION DURING THE DAY NEARBY SURFACE OBSERVATIONS SUGGESTED WINDS HAVE DROPPED TO AROUND 20 KT AT BEST IN THE AREA. OVERNIGHT DRAINAGE FLOW THROUGH THE CHIVELA PASS SHOULD KEEP WINDS AT 20 KT THROUGH THE MORNING HOURS SUN THEN SYNOPTIC SCALE FORCING SHOULD ALLOW WINDS TO DROP TO LIGHT AND VARIABLE THEREAFTER. GULF OF PAPAGAYO...OVERNIGHT DRAINAGE FLOW WILL ENHANCE THE N-NE FLOW CURRENTLY PREVAILING ACROSS THE WESTERN CARIBBEAN. FRESH NORTHEASTERLY GAP WINDS ARE EXPECTED DURING THE NEXT COUPLE OF DAYS...WITH WINDS LIKELY STRONGEST DURING THE LATE NIGHT AND EARLY MORNING HOURS. $$ COBB