000 AXPZ20 KNHC 311541 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT JAN 3A 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1300 UTC. ...ITCZ... INTERTROPICAL CONVERGENCE ZONE AXIS LIES ALONG THE LINE FROM 06N78W TO 04N100W TO 02N115W TO 03N130W TO 02N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 120 NM N AND 30 NM S OF THE ITCZ AXIS E OF 78.5W. ...DISCUSSION... NEAR SHORE S OF 20N... A POTENT COLD FRONT THAT PASSED THROUGH THE WESTERN GULF OF MEXICO THU/FRI HAS BROUGHT STRONG NORTHERLY FLOW THROUGH THE ISTHMUS OF TEHUANTEPEC. THE WESTERN EDGE OF THE 1146 UTC QUIKSCAT PASS HIT THE GULF OF TEHUANTEPEC AND ONLY SHOWED WINDS TO 45 KT...BUT CONSIDERING THAT THE PASS MISSED A PORTION OF THE HIGH WIND AREA AND THE PORTION IT DID HIT IS ON THE EDGE OF THE SWATH...A STORM WARNING CONTINUES UNTIL AFTERNOON TO BE SAFE. WINDS ARE EXPECTED TO QUICKLY DIMINISH THROUGH SUN EVENING TO LESS THAN 20 KT AS THE DEEP LAYER TROUGH SUPPORTING THE FRONT IS SHOVED EASTWARD BY THE NEXT SYSTEM WHICH IS EXPECTED TO CARRY A STRONG COLD FRONT SOUTHWARD INTO NORTHERN MEXICO OVERNIGHT SUN NIGHT. THE 1146 UTC QUIKSCAT PASS SQUARELY HIT THE GULF OF PAPAGAYO WHERE WINDS HAVE INCREASED TO 30 KT AS THE HIGH PRESSURE BEHIND THE FRONT THAT INDUCED THE TEHUANTEPEC WINDS SHIFTS EASTWARD... INCREASING THE SURFACE PRESSURE GRADIENT HERE BETWEEN THE RIDGING OVER THE GULF OF MEXICO AND THE LOW OVER NORTHERN COLOMBIA. THE MAXIMUM WINDS SHOULD BEGIN TO DIMINISH TOMORROW ...BUT EXPECT THE AREA OF WINDS OVER 20 KT TO CONTINUE TO EXPAND WEST THROUGH THE PERIOD. AS THE GULF OF MEXICO HIGH PRESSURE SHIFTS FARTHER EAST...LOOK FOR WINDS TO INCREASE OVER THE GULF OF PANAMA AS WELL. THE 1144 QUIKSCAT PASS SHOWS THAT WINDS HAVE YET TO BUILD TO 20 KT OVER AN APPRECIABLE AREA...BUT THEY ARE EXPECTED TO THIS EVENING. CURRENTLY...SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 60 NM OF THE EASTERN PANAMA/NW COLOMBIA BORDER N OF 06N. THIS CONVECTION WAS SPURRED ON BY UPPER LEVEL DIFFLUENCE ON THE WESTERN EDGE OF A WEAK UPPER LEVEL RIDGE AXIS OVER NW SOUTH AMERICA. THE REGION HAS PLENTIFUL LOW TO MID LEVEL MOISTURE...WITH PRECIPITABLE WATER VALUES IN EXCESS OF 2 INCHES. HOWEVER...THE DIFFLUENCE IS SOMEWHAT WEAK. ELSEWHERE... AN UPPER JET LIES OVER N WATERS...STREAMING HIGH CLOUDS NORTHEASTWARD ACROSS NW WATERS FROM THE WEAK MID TO UPPER LEVEL TROUGH CENTERED W OF THE AREA. ENERGY WAS SHED EARLIER FROM THIS TROUGH INTO THE UPPER JET AND IS NOW PUSHING EASTWARD THROUGH NORTHERN MEXICO. THE REMAINING TROUGHING WILL DRAG EASTWARD...N OF THE ANTICYCLONE CENTERED NEAR 12N105W...BECOMING MORE POSITIVELY TILTED AS IT MOVES THROUGH N WATERS. MID TO LOW LEVEL MOISTURE N OF 20N W OF 130W ASSOCIATED WITH THE TROUGH WILL WANE THE NEXT FEW DAYS AS A RESULT...AND NO SIGNIFICANT CONVECTION IS EXPECTED WITH THIS FEATURE OVER FORECAST WATERS. AT THE SURFACE...HIGH PRESSURE DOMINATES WATERS W OF 120N...BUT SHOULD BE WEAKENING THROUGH THE WEEKEND INTO MON AS THE HIGH CENTERED WELL N OF THE AREA IS PUSHED INTO THE PACIFIC NW U.S. BY THE NEXT APPROACHING LONGWAVE TROUGH RACING EASTWARD ACROSS THE NORTH CENTRAL PACIFIC. WEAKENING OF THE SURFACE RIDING OVER FORECAST WATERS WILL SLACKEN THE PRESSURE GRADIENT BETWEEN IT AND LOW PRESSURE OVER THE GULF OF CALIFORNIA...BRINGING WINDS IN THE GULF UNDER 20 KT LATER TODAY. IT WILL ALSO DIMINISH THE AREA OF TRADE WINDS IN EXCESS OF 20 KT OVER W WATERS S OF 20N. $$ SCHAUER CLARK