000 AXPZ20 KNHC 101002 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC TUE JAN 10 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 0915 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 08N75W TO LOW PRES NEAR 04.5N79W 1010 MB TO 05.5N83W TO 04N91W TO 07N105W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING TO 06N123W TO 07N130W TO BEYOND 05N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 210 NM N OF AXIS BETWEEN 123W AND 132W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS OCCURRING WELL N OF THE ITCZ...FROM 13N TO 18N W OF 127W. ...DISCUSSION... A BLOCKING PATTERN IN THE UPPER LEVELS CONTINUED TO SPAN FROM THE TROPICAL CENTRAL PACIFIC EWD TO THE WRN CARIBBEAN. A LINGERING CUT OFF CYCLONE IN THE MIDDLE TO UPPER LEVELS REMAINED ACROSS W PORTIONS OF THE AREA...CENTERED NEAR 21N138W...WITH A WEAKENING MIDDLE TO UPPER LEVEL TROUGH MEANDER TO THE N-NE...TO A WEAKENING MID LEVEL CYCLONE NEAR 33N125W...WHILE A SHARP UPPER TROUGH CONTINUED S FROM THE CYCLONE ALONG 138W TO NEAR THE EQUATOR ALONG 140W. LOW TO MID LEVEL CONVERGENCE INDUCED E THROUGH SE OF THE UPPER TROUGH ALONG 138W CONTINUES TO PRODUCE AREAS OF MODERATE TO DEEP CONVECTION...SOME ELEVATED...AND ABUNDANT HIGH CLOUDS SPREADING NE ACROSS MUCH OF THE AREA N OF THE ITCZ TO 110W. THIS UPPER TROUGH WILL DRIFT E OVER THE NEXT FEW DAYS AND CONTINUE TO AID IN THE DEVELOPMENT OF ACTIVE CONVECTION S OF 20N BETWEEN 120W AND 140W...WHILE A REINFORCING UPPER CYCLONE DEVELOPS N OF THE AREA AND SINKS OF 30N ALONG 128/129W LATE THU. HIGH PRES N OF THE AREA HAS COLLAPSED DURING THE PAST 12-18 HRS...AHEAD OF A COLD FRONT MOVING INTO NRN CALIFORNIA. A LOW LEVEL WEAKNESS HAS DEVELOPED BETWEEN 122W AND 128W N OF 25N DURING THE PAST COUPLE OF DAYS...AND WILL PERSIST IN SOME FORM OVER THE NEXT SEVERAL DAYS...IN EFFECT BLOCKING HIGH PRES AND RESULTANT FRESH TRADEWINDS FROM BUILDING ACROSS THE AREA. A SUFFICIENT PRES GRADIENT PERSISTS N OF THE ITCZ FROM 07N TO 11N BETWEEN 125W AND 138W TO MAINTAIN FRESH NE TRADEWINDS EARLY THIS MORNING...WITH THESE FRESH TRADEWINDS EXPECTED TO DIMINISH IN AREAL COVERAGE AND SHIFT AWAY FROM THE ITCZ TO BETWEEN 16N AND 23N W OF 137W BY THU MORNING. SEAS ACROSS MUCH OF THE AREA ARE OTHERWISE DOMINATED BY LONG PERIOD NW SWELL MOVING THROUGH THE WATERS...WITH A NEW PULSE OF NW SWELL CURRENTLY MOVING ACROSS NW PORTIONS. COMBINED SEAS OF 8 TO 10 FT CURRENTLY COVER MUCH OF THE AREA W OF 125W....WITH SEAS TO 11 FT ACROSS PORTIONS OF THE AREA OF FRESH TRADEWINDS. THESE NW SWELLS WILL SLOWLY SUBSIDE AS THE PROPAGATE SE DURING THE NEXT FEW DAYS. GULF OF PAPAGAYO...TRADEWINDS HAVE BECOME MORE NW TO N ACROSS THE FAR SW CARIBBEAN AND ARE SPILLING S THROUGH THE GULF OF PANAMA TO NEAR 20 KT. THIS HAS WEAKENED THE WIND FLOWING THROUGH THE GAPS IN THE TOPOGRAPHY OVER NICARAGUA AND COSTA RICA INTO THE GULF OF PAPAGAYO...WITH WINDS SUGGESTED TO HAVE FALLEN BELOW 20 KT THIS MORNING BY A 0254 UTC ASCAT PASS. WINDS ACROSS THIS REGION ARE EXPECTED TO GENERALLY REMAIN BELOW 20 KT...BUT MAY INCREASE EACH OF THE NEXT EARLY MORNINGS...WITH THE 0NOCTURNAL DRAINAGE FLOW. GULF OF CALIFORNIA...HIGH PRESSURE PREVAILS OVER THE GREAT BASIN REGION...BUT HAS WEAKENED ITS INFLUENCE CONSIDERABLY ACROSS THE DESSERT SW OF THE U.S. AND INTO BAJA CALIFORNIA. A A RESULT THE PRES GRADIENT DRIVING FRESH TO STRONG NWLY WINDS THROUGH THE GULF OF CALIFORNIA HAS DIMINISHED. NWLY WINDS AROUND 20 KT CURRENTLY PERSIST THROUGH THE NRN GULF TO 25N...AND WILL CONTINUE TO WEAKEN TODAY...DIMINISHING BELOW 20 KT THIS AFTERNOON. GULF OF TEHUANTEPEC...A COLD FRONT OVER THE NW GULF OF MEXICO WILL REACH THE BAY OF CAMPECHE ON TUE. A COLD AIR MASS BEHIND THE FRONT WILL SETTLE OVER THE GULF OF MEXICO...TIGHTENING THE PRESSURE GRADIENT BETWEEN THE GULF OF MEXICO AND EASTERN PACIFIC. THIS WILL RESULT IN FRESH NLY WINDS AROUND 20 KT BEGINNING TUESDAY NIGHT. WINDS ACROSS THE GULF OF MEXICO WILL VEER RAPIDLY SE AS THE AIR MASS MODIFIES ON WEDNESDAY. AS A RESULT...THE EPISODE OF FRESH 20 KT WINDS OVER THE GULF OF TEHUANTEPEC WILL BE SHORT LIVED AND DIMINISH BELOW 20 KT BY WED EVENING. $$ STRIPLING