000 AXPZ20 KNHC 072203 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC WED DEC 07 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM LOW PRES NEAR 06N78W 1009 MB TO 08N85W TO 05N96W TO 05N108W WHERE LOW LEVEL WINDS THEN INDICATE THAT IT TRANSITIONS TO ITCZ AND EXTENDS TO TROUGH ALONG 07N123W 12N117W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM N OF THE ITCZ BETWEEN 124W-128W...AND 120 NM N OF THE ITCZ BETWEEN 130W-138W. ...DISCUSSION... A STRONG BLOCKING UPPER PATTERN PERSISTS ACROSS THE BROADER REGION BETWEEN 80W AND 160W....WITH A SERIES OF COMPLEX TROUGHS GENERALLY W OF 120W...AND A BROAD UPPER RIDGE CENTERED ACROSS THE NW U.S. A FAIRLY HIGH AMPLITUDE TROUGH EXTENDING SSW FROM 32N147W TO JUST SE OF THE BIG ISLAND OF HAWAII NEAR 15N155W. STRONG AND DIFFLUENT SWLY MID TO UPPER LEVEL FLOW ROUNDING THE BASE OF THIS TROUGH COVERS A BROAD ZONE OF THE DISCUSSION AREA GENERALLY FROM 06N TO 27N W OF 127W. THIS AREA OF DIFFLUENT FLOW WAS PROVIDING A FAVORABLE ENVIRONMENT FOR SCATTERED DEEP CONVECTION WITHIN 180 NM N OF THE ITCZ BETWEEN 124W-128W...AND ALSO WITHIN 120 N OF THE ITCZ BETWEEN 130W-138W AS DESCRIBED ABOVE. TO THE SE...A DOWNSTREAM RIDGE IS ANCHORED ON AN UPPER ANTICYCLONE JUST S OF THE GULF OF TEHUANTEPEC EXTENDING NE ACROSS THE NW CARIBBEAN AND INTO THE WRN N ATLC WELL BEYOND 32N73W. DRY AND STABLE ATMOSPHERIC CONDITIONS PREVAIL UNDER THE RIDGE E OF 105W...EXCEPT WHERE A WEAK TUTT AXIS HAS DEVELOPED OVER THE MONSOON TROUGH BETWEEN 87W AND 95W AND WAS AIDING IN PROVIDING MID LEVEL LIFT FOR ACTIVE CONVECTION THERE. THE OVERALL BROAD SCALE PATTERN WILL CHANGE LITTLE OVER THE DISCUSSION AREA THROUGH THE NEXT 24-48 HRS AS THIS REX-TYPE BLOCKING PATTERN CONTINUES N OF THE REGION...ALLOWING FOR BROAD RIDGING TO PREVAIL WITH NO FRONTS EXPECTED TO CROSS S OF 32N. GULF OF TEHUANTEPEC...HIGH PRES BUILDING SWD ALONG THE SIERRA MADRE OF MEXICO HAS INCREASED THE PRES GRADIENT BETWEEN THE NORTHERN COAST OF THE ISTHMUS OF TEHUANTEPEC AND ITS SOUTHERN TERMINUS BEHIND A STALLED COLD FRONT OVER THE SW GULF OF MEXICO. THE GAP FLOW HAS REACHED GALE FORCE AS NOTED IN VERY CLEAR ASCAT PASS FROM NEAR 1530 UTC THIS MORNING. THE PASS SHOWED WIND VECTORS OF UP TO 40 KT THROUGH THE GULF. THE GALE EVENT IS FORECAST TO PEAK TONIGHT WITH WINDS REACHING TO JUST BELOW STORM FORCE STRENGTH BEFORE BEGINNING A DOWNWARD TREND TO EVENTUALLY BACK TO LESS THAN GALE FORCE EARLY FRI. DOWNSTREAM SEAS ARE EXPECTED TO REACH A MAXIMUM OF AROUND 14 FT TONIGHT BEFORE SLOWLY SUBSIDING TO 8-10 FT THU AND FRI. GULF OF CALIFORNIA...HIGH RESOLUTION ASCAT DATA FROM THIS AFTERNOON REVEALED THAT NW-N WINDS OF 20-25 KT THAT WERE EVIDENT TO THE N OF 23N...AND ALSO FROM 20N-23N E OF 109W ARE GRADUALLY DIMINISHING. IT APPEARS THAT N-NE WINDS OF SIMILAR SPEEDS THAT EARLIER WERE QUITE EVIDENT SEEPING THROUGH PASSES ALONG THE BAJA COAST AND INTO THE OPEN PACIFIC HAVE SINCE DIMINISHED TO LOWER SPEEDS AS WELL. AS THE PRES GRADIENT CONTINUES TO FURTHER SLACKEN OVER THE NEXT 24-30 HRS...WINDS WILL RESPOND BY DIMINISHING TO 20 KT AND LESS BY DAYBREAK THU. FURTHER SW...A SURFACE TROUGH EXTENDS FROM FROM 07N123W TO 12N117W. THIS FEATURE CONTINUES MOVING WESTWARD AT 10 KT. THE COMBINATION OF STRONG SW UPPER SHEAR AND DEEP LAYERED SUBSIDENCE HAS TOTALLY DISSIPATED THE PREVIOUS LARGE CLUSTERS OF STRONG CONVECTION NOTED WITH THE TROUGH/FORMER LOW. THE TROUGH WILL CONTINUE ON A WESTWARD TRACK AND WILL LIKELY DISSIPATE ALTOGETHER BY 48 HRS. THE PRES GRADIENT BETWEEN THE TROUGH AND HIGH PRES RIDGING TO ITS N WILL ALLOW FOR WINDS OF 20-25 KT OVER AN AREA FROM 13N TO 20N W OF 133W AND FROM 12N TO 20N BETWEEN 126W AND 133W WITH SEAS OF 8-10 FT THROUGH 24 HRS. GULF OF PAPAGAYO...NE 20 KT WINDS WILL CONTINUE TO PULSE UP AND DOWN DOWNWIND OF THE GULF OF PAPAGAYO THROUGH THE NEXT 48 HOURS IN THE LATE NIGHT AND EARLY MORNING HOURS DURING PEAK DRAINAGE FLOW OFF CENTRAL AMERICA. THESE OCCURRENCES SHOULD NOT LAST LONG ENOUGH TO BE INCLUDED IN THE HIGH SEAS FORECAST. $$ AGUIRRE