000 AXPZ20 KNHC 302207 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU APR 30 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2115 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG...7N78W 7N89W 7N98W 8N105W TO 6N115W 9N129W TO 6N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS FROM 4N-9N BETWEEN 118W-123W...WITHIN 120 NM N OF THE AXIS W OF 137W AND FROM 5N-7N BETWEEN 82W-84W. ...DISCUSSION... AS IN PREVIOUS DAYS...HIGHLY AMPLIFIED FEATURES DENOTE THE AREA. HE FIRST IS A BROAD RIDGING AT ALL LEVELS OVER THE CENTRAL PORTION OF THE AREA WITH A MEAN MID/UPPER AXIS EXTENDING THROUGH 32N118W S TO 23N118W TO 19N120W TO A NEARLY STATIONARY WELL ANCHORED ANTICYCLONE NEAR 9N120W. A WEAK LOW TO MID LEVEL TROUGH IN THE VICINITY OF THE ITCZ EXTENDS FROM 8N137W TO 2N134W. UPPER LEVEL DIFFLUENCE BETWEEN THE TROUGH AND THE ANTICYCLONE IN OVER THE SURFACE TROUGH DESCRIBED BELOW HAD RESULTED IN ENHANCED CONVECTION NEAR THE ITCZ BETWEEN 122W-129W. THE TROUGH IS FORECAST TO LOSE ITS IDENTITY OVER THE NEXT 12-24 HRS AS THE DEEP LAYER TROUGH DESCRIBED BELOW TAKES PRECEDENCE. ANOTHER RIDGE EXTENDS FROM THE ANTICYCLONE NE TO 17N116W TO ACROSS BAJA CALIFORNIA AND NW MEXICO. A NEARLY STATIONARY MID/UPPER LEVEL TROUGH IS OVER THE FAR ERN PORTION OF THE AREA EXTENDING FROM SE MEXICO SW TO A SMALL CUT-OFF UPPER LEVEL LOW NEAR 13N97W. BROKEN MID AND UPPER LEVEL CLOUDS ARE BEING CHANNELED NEWD ACROSS CENTRAL AMERICA E OF THE TROUGH WITH SCATTERED SHOWERS AND TSTMS OVER CENTRAL AMERICA AND WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE E PACIFIC WATERS N OF THE ITCZ E OF 92W UNDER AN ASSOCIATED JET STREAM BRANCH THAT EXTENDS FROM 8N91W NNE TO ACROSS HONDURAS AND INTO THE WRN CARIBBEAN SEA. THE SHOWER AND TSTM ACTIVITY WILL CONTINUE THROUGH AT LEAST THE NEXT 48 HRS AS THE LOW AND TROUGH REMAIN ABOUT STATIONARY. THE RIDGE IS FORECAST TO DAMPEN OUT SOME AS IT GETS NUDGED EWD TO OVER THE WRN U.S. WITHIN THE NEXT 2 DAYS BY A RATHER SHARP DEEP LAYER TROUGH PRESENTLY ALONG 136W/137W. A VERY WELL PRONOUNCED NRN STREAM JET STREAM BRANCH WITH MAXIMUM WINDS OF 60-90 KT SHARPLY DIVES SWD INTO THE BACK SIDE OF THE TROUGH THEN ENTERS THE REGION AT 13N140W...AND CONTINUES NE TO 25N130W TO ACROSS SRN CALIFORNIA. THE TROUGH BEGIN TO SHEAR OUT FRI INTO SAT OVER ACROSS THE ERN AND CENTRAL SECTIONS OF THE AREA. ITS SURFACE REFLECTION IS OBSERVED AS A COLD FRONT THAT IS CURRENTLY JUST NW OF THE AREA. A FRONTAL TROUGH FROM 32N135W TO 27NW138W WILL MERGE INTO A COLD FRONT PRESENTLY JUST NW OF THE AREA LATE TONIGHT. AT THE PRESENT TIME...DEEP LAYER MOISTURE CONSISTING OF BROKEN MULTILAYERED CLOUDS WITH SCATTERED SHOWERS AND TSTMS IS ADVECTING NEWD INTO THE FAR NW WATERS MAINLY AS A RESULT OF THE ABOVE JET STREAM ROUNDING THE BASE OF THE TROUGH BRINGING ADDITIONAL MOSITURE FROM THE DEEP TROPICAL PACIFIC NEWD INTO THE WRN PART OF THE AREA. BROAD/MID UPPER LEVEL RIDGING COVERING THE WRN CARIBBEAN SEA ALSO EXTENDS W ACROSS CENTRAL AMERICA TO THE E OF THE MID/UPPER LEVEL TROUGH OVER THE ERN PORTION OF THE AREA. AT THE SURFACE...HIGH PRES OF 1026 MB IS NEAR 30N126W WITH A RIDGE SE TO 24N118W TO 18N110W. AS THE TROUGH W OF THE AREA ADVANCES EWD THROUGH THE NEXT 48 HRS...THE RIDGE WILL ALSO SLIDE E WHILE LOW PRES DEEPENS OVER THE PLAINS INTO NRN MEXICO. THIS WILL ALLOW FOR THE PRES GRADIENT TO INCREASE OVER THE NE PART OF THE AREA INCREASING NW WINDS ALONG THE BAJA CALIFORNIA COAST TO THE RANGE OF 20-25 KT IN 24 HRS...THEN DIMINISHING SLIGHTLY IN 48 HRS AND INCREASING ONCE AGAIN AFTER THAT. S-SW WINDS OF 20 KT WITHIN 180 NM E OF THE FRONTAL TROUGH N OF 28N WILL BECOME S-SW AND INCREASE TO 20-25 KT LATE TONIGHT AS IT MERGES WITH A COLD FRONT ALSO ASSOCIATED WITH THE SAME UPPER TROUGH MOVING INTO THE NW WATERS REACHING FROM 30N137W TO 27N140W LATE. SW OF 20-25 KT WILL OCCUR N OF 28N WITHIN 300 NM E OF FRONT IN 24 HRS...THEN DIMINISH TO LESS THAN 20 KT IN 48 HRS AS THE FRONT DISSIPATES OVER THE FAR NE PART. A WEAK TROUGH MOVING WNW 15 KT EXTENDS FROM 8N131W TO 14N129W. THIS FEATURE ALONG WITH THE WEAK LOW AND MID LEVEL TROUGH TO ITS W HAD EARLIER INCREASED ITCZ CONVECTION...BUT THE CONVECTION HAS RECENTLY WEAKENED. GAP WINDS...NE WINDS OF 20 KT IN THE GULF OF PAPAGAYO ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT IN ABOUT 24 HRS AS WINDS IN THE SW CARIBBEAN SEA WEAKEN. $$ AGUIRRE