000 AXPZ20 KNHC 270317 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT MAR 27 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0145 UTC. ...ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 04N77W TO 08N95W TO 05N115W TO 03N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 210 NM N OF THE ITCZ AXIS BETWEEN 102W AND 120W. ...DISCUSSION... SUBTROPICS... A WEAK UPPER TROUGH OVER NW WATERS WILL BE REINFORCED BY A DEEP LAYER TROUGH CURRENTLY N OF THE HAWAIIAN ISLANDS...SHIFTING THE RELATIVELY ZONAL SUBTROPICAL JET AXIS SW TO NE ACROSS THE AREA FROM 10N140W INTO CENTRAL BAJA CALIFORNIA BY SUN EVENING AT THE END OF THE FORECAST PERIOD. A WEAK COLD FRONT ASSOCIATED WITH THE DEEP LAYERED TROUGH WILL MOVE INTO NW WATERS SAT NIGHT AND WILL BRING A NEW SURGE OF NW SWELL INTO THE FORECAST AREA WITH SEAS REACHING AS HIGH AS 16 FT BY SUN AFTERNOON. THE PRESSURE GRADIENT BETWEEN THE ITCZ AND A 1028 MB HIGH PRESSURE LOCATED N OF AREA NEAR 36N127W IS MAINTAINING A BROAD AREA OF FRESH TO STRONG TRADE WINDS GENERALLY FROM 04N TO 20N AND W OF 125W...WHERE SEAS ARE RUNNING 8 TO 11 FT IN MIXED NE AND NW SWELL. THE HIGH PRES CENTER WILL WEAKEN SAT AND SHIFT S AHEAD OF THE FRONT MOVING INTO NW WATERS. THIS WILL REDUCE THE AREA OF FRESH TO STRONG TRADES. BY SUN AFTERNOON...THE COLD FRONT WILL BEGIN TO DISSIPATE AND THE HIGH WILL BEGIN TO MERGE WITH HIGH PRES NW OF THE FRONT...ALLOWING FOR TRADES TO BEGIN TO EXPAND AGAIN TO THE N. IN ADDITION...THE PRES GRADIENT BETWEEN THE 1028 MB HIGH AND LOWER PRES ALONG THE SIERRA NEVADA AND THE SIERRA MADRE OCCIDENTAL WILL MAINTAIN WINDS OF 20-25 KT FROM OFFSHORE OF SOUTHERN CALIFORNIA TO ALONG THE WEST COAST OF THE NORTHERN BAJA PENINSULA THROUGH MORNING...THEN WEAKEN ACROSS THE PACIFIC WATERS BUT GRADUALLY INCREASE TO 20-25 KT THROUGHOUT THE ENTIRE LENGTH OF THE GULF OF CALIFORNIA FROM THIS EVENING THROUGH SAT EVENING AND CONTINUE THROUGH THE FORECAST PERIOD. TROPICS... AN AMPLIFIED UPPER PATTERN IS IN PLACE ALOFT OVER THE TROPICAL NORTH EAST PACIFIC. AN ANTICYCLONIC CIRCULATION CENTERED OVER THE CENTRAL CARIBBEAN EXTENDS A RIDGE W ACROSS NICARAGUA INTO THE EASTERN PACIFIC TO NEAR 10N120W AND ON TO NEAR 08N125W. TO ITS W LIES A NEGATIVELY TILTED UPPER TROUGH FROM 12N136W TO 00N126W. A POOL OF MOISTURE IS CONVERGED ALONG THE ITCZ NEAR A SURFACE TROUGH EMBEDDED IN IT FROM 09N108W TO 00N108W. THE DIFFLUENT PATTERN ALOFT BETWEEN THE WESTERN SIDE OF THE RIDGE AND THE NEGATIVELY TILTED UPPER TROUGH OVER THIS LOW LEVEL MOISTURE CONVERGENCE IS PRODUCING SCATTERED MODERATE CONVECTION ALONG THE ITCZ BETWEEN 102W AND 120W. GAP WINDS... THE 1620 UTC ASCAT PASS SHOWED N TO NE WINDS TO 30 KT NEAR THE COAST OF THE GULF OF TEHUANTEPEC AND SHIP 3FBE8 NEAR 14N96W REPORTED 23 KT WINDS AT 1700 UTC. THERE ARE NO MORE RECENT OBSERVATIONS HERE...BUT BUOY 42055 IN THE SW GULF OF MEXICO HAS HAS TURNED MORE EASTERLY BETWEEN 2100 UTC AND 0200 UTC...SO THE WINDS ARE BELIEVED TO BE DIMINISHING IN THE GULF OF TEHUANTEPEC. WINDS ARE EXPECTED TO DIMINISH BELOW 20 KT THROUGH TOMORROW AFTERNOON AS WINDS SHIFT SOUTHEASTWARD IN THE SW GULF OF MEXICO. THE COLD FRONT THAT BROUGHT STRONG N WINDS TO TEHUANTEPEC WILL NOT DIP AS FAR S AS THE GULF OF PAPAGAYO...BUT IT HAS FORCED THE RIDGE AXIS SOUTHWARD IN THE WESTERN CARIBBEAN AHEAD OF IT. AS A RESULT...THE PRES GRADIENT HAS BUILT BETWEEN THE RIDGE AXIS AND LOW PRES OVER COLOMBIA. THIS WILL INDUCE 20-25 KT GAP WINDS THROUGH THE GULF OF PAPAGAYO OVERNIGHT TONIGHT WITH THE ASSISTANCE OF DRAINAGE FLOW. SIMILARLY...N TO NE WINDS WILL ALSO INCREASE TO 20 KT IN THE GULF OF PANAMA BY SAT EVENING. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ SCHAUER