000 AXPZ20 KNHC 300311 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU APR 30 2009 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 0300 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG...5N78W 7N86W 7N98W 5N107W TO 6N120W 4N130W TO 4N140W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS WITHIN 240 NM S OF THE AXIS BETWEEN 86W-90W AND 150 NM N OF THE AXIS BETWEEN 122W-127W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 118W-122W... AND BETWEEN 127W-132W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 132W-138W. ...DISCUSSION... A PROGRESSIVE PATTERN IS PRESENT ACROSS THE REGION AS DENOTED BY HIGHLY AMPLIFIED FEATURES. THE FIRST IS A BROAD RIDGING AT ALL LEVELS OF THE ATMOSPHERE OVER THE CENTRAL PORTION OF THE AREA WITH A MEAN MID/UPPER RIDGE AXIS EXTENDING INTO THE AREA THROUGH 32N124W TO 18N121W TO 17N118W TO A STATIONARY ANTICYCLONE NEAR 9N117W. A WEAK LOW TO MID LEVEL TROUGH IN THE VICINITY OF THE ITCZ EXTENDS FROM 10N122W TO 5N129W. UPPER LEVEL DIFFLUENCE BETWEEN THE TROUGH AND THE ANTICYCLONE CONTINUES TO ENHANCE ITCZ CONVECTION BETWEEN 122W-129W. THE TROUGH IS FORECAST TO LIFT NE GENERALLY TOWARDS THE DEEP LAYER TROUGH DESCRIBED BELOW. ANOTHER RIDGE EXTENDS FROM THE ANTICYCLONE NE TO 16N110W TO ACROSS CENTRAL MEXICO. MID/UPPER TROUGHING NE OF THE RIDGE HAS MOVED E TO OVER NRN MEXICO AND THE SW U.S. A NEARLY STATIONARY MID/UPPER LEVEL TROUGH IS OVER THE FAR ERN PORTION OF THE AREA EXTENDING FROM SE MEXICO SW TO TO A RECENTLY FORMED CUT-OFF UPPER LEVEL LOW NEAR 12N97W. BROKEN MID AND UPPER LEVEL CLOUDS ARE BEING CHANNELED NEWD ACROSS CENTRAL AMERICA E OF THE TROUGH WITH SCATTERED SHOWERS AND TSTMS INCREASING NE THROUGH SE OF THE TROUGH AND LOW...MAINLY OVER WATER ALONG AND N OF THE ITCZ BETWEEN 84W-87W 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 W OF THE AREA PRESENTLY ALONG 144W/145W. 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 15N140W...AND CONTINUES NE TO 20N135W TO 25N125W...AND DIVES SEWD OVER THE RIDGE TO 24N115W TO 16N109W. THE JET WILL DRIVE THE TROUGH EWD TO ACROSS 140W ON THU...AND TO NEAR 135W BY THU EVENING...THEN 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 CURRENTLY EXTENDS 30N137W SW TO 23N140W. THE FRONT WILL WEAKEN INTO A FRONTAL TROUGH FROM 30N134W TO 22N140W IN ABOUT 24 HRS ...AND DISSIPATE IN 48 HRS. 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 JUST N OF THE AREA NEAR 33N127W EXTENDS A RIDGE SE TO 24N118W TO 18N111W. AS THE TROUGH W OF THE AREA ADVANCES EWD THROUGH THE NEXT 48 HRS...THE RIDGE WILL ALSO SLIDE E AS 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 THE NW WINDS ALONG THE BAJA CALIFORNIA COAST REACHING W TO NEAR 118W IN 24 HRS...THEN DIMINISHING TO LESS THAN 20 KT IN 48 HRS. SE-S WINDS OF 20-25 KT E OF THE COLD FRONT WILL DIMINISH AND BECOME SW 20 KT IN 48 HRS AS THE FRONT DISSIPATES...BUT THE TAIL END OF A NEW COLD FRONT WILL BRUSH THE AREA ALONG 30N NEAR 128W IN 48 HRS WITH SLIGHTLY STRONGER SW WINDS JUST N OF 30N. A WEAK TROUGH MOVING W 15 KT IS ALONG 130W FROM 3N-9N. THIS FEATURE ALONG WITH THE WEAK LOW AND MID LEVEL TROUGH TO ITS W IS AIDING ITCZ CONVECTION TO ITS E. GAP WINDS...NE WINDS OF 20-25 KT THROUGH THE GULF OF PAPAGAYO ARE EXPECTED TO DIMINISH TO LESS THAN 20 KT IN ABOUT 30 HRS AS WINDS IN THE SW CARIBBEAN SEA WEAKEN. $$ AGUIRRE