000 AXPZ20 KNHC 041001 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH CROSSES CENTRAL AMERICA AND ENTERS THE EPAC NEAR 09N84W TO 05N96W THEN TRANSITIONS TO ITCZ TO LOW PRES 1010 MB NEAR 08N105.5W TO 06N114W TO WEAK LOW PRES 1011 MB NEAR 10N121.5W TO 08N140W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 60-90 NM OF ITCZ W OF 139W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED FROM 04N TO 06W E OF 80W. ...DISCUSSION... A SHARP UPPER LEVEL TROUGH EXTENDS ACROSS WRN N AMERICA TO A WELL DEFINED DEEP LAYERED CYCLONE OVER S CENTRAL ARIZONA NEAR 33N112W INTO THE PACIFIC WATERS TO A BROAD BASE NEAR 20N114W. REINFORCING SHORTWAVE ENERGY CONTINUES TO SINK S ACROSS BACKSIDE OF TROUGH AND HAS BECOME ABSORBED INTO THE DEEP LAYERED CYCLONE NOTED ABOVE...AIDING IN DIGGING THE MEAN TROUGH SLIGHTLY S OVER THE PAST 24 HOURS AND IN BROADENING THE TROUGH BASE OVER THE AREA TO BETWEEN 100W AND 135W. 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 08N99W EXTENDING N-NE ACROSS MUCH OF CENTRAL AMERICA...SOUTHERN MEXICO AND OVER THE GULF OF MEXICO. THE DEEP LAYERED CYCLONE EXTENDS TO NEAR THE SURFACE ACROSS SRN ARIZONA WITH TROUGHING EXTENDING SW ACROSS NRN BAJA CALIFORNIA TO 29N120W. A 1042 MB HIGH ACROSS THE NE PACIFIC NEAR 43N135W IS COMBINING WITH THIS LOW PRES OFF OF NRN BAJA CALIFORNIA TO PRODUCE FRESH NE WINDS N OF 28N W OF 132W...AND THEN S OF THE HIGH TO THE ITCZ...FROM 08N TO 18N W OF 135W...WHILE NE WINDS TO NEAR 20 KT PREVAILED THERE BETWEEN 18N AND 28N. SEAS OF 8 TO 11 FT PREVAIL ACROSS THIS AREA IN A MIX OF N AND NEW NW SWELL...AND BUILDING NE WIND WAVES...EXCEPT TO 12 FT ALONG 30N AS CONFIRMED BY RECENT ALTIMETER PASSES. THIS WIND FLOW WILL DIMINISH AND VEER MORE NE TO E THROUGH 48 HOURS AND EXPAND EASTWARD BETWEEN 12N AND 20N TO ALONG 115W OR SO AS HIGH PRES N OF THE AREA WEAKENS SLIGHTLY AND DRIFTS E. THE DEEP LAYERED CYCLONE OVER ARIZONA IS FORECAST TO ROTATE EASTWARD WITHIN THE MEAN TROUGH OVER THE NEXT 24 HOURS AND ALLOW HIGH PRESSURE TO BUILD INTO THE SOUTHWEST CONUS AND ACROSS THE GULF OF CALIFORNIA REGION LATER TODAY TO PRODUCE FRESH TO LOCALLY STRONG NORTHERLY WINDS PERSISTING THROUGH THE GULF THROUGH MON NIGHT. A 0406 UTC ASCAT PASS SHOWED NLY WINDS OF 20 KT ALREADY SPILLING INTO FAR N PORTIONS OF THE GULF THIS MORNING. A SECOND AND STRONGER SURGE OF NW WINDS IS EXPECTED TUE AND WED...WITH WINDS 20 TO 30 KT...AND POSSIBLY REACHING GALE FORCE. SEAS WILL BUILD TO 8 FT AND HIGHER ACROSS PORTIONS OF THE GULF DURING THIS TIME. TO THE SE...A 1010 MB LOW PRES CENTER REMAINS EMBEDDED WITHIN THE ITCZ NEAR 08N105.5W MOVING W AT AROUND 10 KT. A 0400 UTC ASCAT PASS 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 AND A GENERALLY STABLE MIDDLE TO UPPER ATMOSPHERE IS PREVENTING ANY MAJOR CONVECTIVE ACTIVITY NEAR THIS LOW PRES PRESENTLY. GULF OF TEHUANTEPEC...A 0400 UTC ASCAT PASS REVEALED DIMINISHING NLY WIND FLOW ACROSS THE GULF REGION...WITH 20-25 KT WINDS DEPICTED GENERALLY N OF 15N. OVERNIGHT DRAINAGE FLOW THROUGH THE CHIVELA PASS SHOULD KEEP WINDS AT 20 KT THROUGH THE MORNING HOURS THEN SYNOPTIC SCALE FORCING SHOULD ALLOW WINDS TO DROP TO LIGHT AND VARIABLE THEREAFTER AS SLY RETURN FLOW HAS BECOME ESTABLISHED ACROSS THE WRN GULF OF MEXICO. A COLD FRONT FORECAST TO MOVE THROUGH THE W GULF OF MEXICO LATE MON AND TUE WILL RE-INITIATE NLY WINDS THROUGH THE GULF OF TEHUANTEPEC BEGINNING EARLY TUE...WITH THE POSSIBILITY OF MINIMAL GALES THERE BY TUE NIGHT. 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. $$ STRIPLING