000 AXPZ20 KNHC 180959 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON MAY 18 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0815 UTC. ...ITCZ... THE AXIS WAS ALONG 08N78W TO 08N86W TO 08.5N98W TO 13N112W TO 1007 MB LOW PRES NEAR 11N116W TO 07N126W TO 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS WITHIN 150 NM EITHER SIDE OF LINE 03N85W TO 11N103W...AND WITHIN 240 NM EITHER SIDE OF AXIS BETWEEN 112W AND 125W. ...DISCUSSION... ALOFT...TWO WELL DEFINED DEEP LAYERED CYCLONES ARE NOTICED. THE WESTERNMOST CYCLONE IS STATIONARY N OF THE HAWAIIAN ISLANDS NEAR 28N156W WITH ITS ENVELOPE OF CYCLONIC FLOW EXTENDING E OVER THE DISCUSSION ALONG 24N140W TO 30N136W...DEFINED BY AN UPPER MOISTURE PLUME ALONG THE E PERIPHERY OF THE ANTICYCLONIC ENVELOPE. AN UPPER TROUGH THAT EXTENDS ACROSS EASTERN N AMERICA FROM NE TO SW CONTINUES W INTO THE DISCUSSION AREA FROM 31N90W TO 30N110W BECOMING A SHEAR AXIS W INTO THE EASTERNMOST CYCLONE...CENTERED NEAR 29N124W...WITH AN UPPER TROUGH CONTINUING S TO A BASE AT 12N118W. AN UPPER LEVEL ANTICYCLONE ESTIMATED NEAR 07N136W HAS A SHORTWAVE RIDGE EXTENDING N TO A SHARP CREST 22N136W. A SECOND UPPER ANTICYCLONE HAS FORMED ALONG THE PARENT LONGWAVE RIDGE OVER NE UTAH WITH ANTICYCLONIC FLOW CONTINUING TO DOMINATE MOST OF WESTERN N AMERICA TO THE W AND N OF THE IMPRESSIVE TROUGH JUST MENTIONED. THE RESULT OF THESE UPPER FEATURES IS A LARGE AREA OF VERY DRY UPPER AIR OVER MOST OF THE W PORTION OF THE DISCUSSION AREA...ROUGHLY TO THE N AND W OF A LINE ALONG 13N140W TO 13N118W TO 26N107W. A QUASI STATIONARY UPPER ANTICYCLONE IS CENTERED NEAR 12N106W WITH A SHORTWAVE RIDGE CRESTING OVER OLD MEXICO ALONG POINTS 23N109W TO 24N101W TO 21N85W. UPPER DIFFLUENCE UNDER THIS BROAD RIDGE HAS BEEN ENHANCING CONVECTION ALONG AND N OF THE ITCZ BETWEEN 96W AND 125W...WITH SOME OF THE DEBRIS MOISTURE SPREADING NE ACROSS OLD MEXICO TO THE TOP OF THE RIDGE CREST AND SPILLING SE ACROSS THE RIDGE AXIS OVER THE W GULF OF MEXICO. A STATIONARY UPPER RIDGE EXTENDS W ACROSS NORTHERN VENEZUELA AND COLOMBIA TO A CREST OVER THE COLOMBIA AND PANAMA BORDER. A DEEP LAYERED CYCLONE OVER THE SRN WINDWARD PASSAGE HAS AN UPPER TROUGH EXTENDING SSW ACROSS W PANAMA CROSSING THE EQUATOR NEAR 80W. THIS MID TO UPPER TROUGH SEPARATES THE FLOW ASSOCIATED WITH THE S AMERICAN RIDGE FROM THE TROPICAL E PACIFIC RIDGE DESCRIBED ABOVE. E PACIFIC ITCZ CONVECTION IS ENHANCED BETWEEN 100W AND 78W WITH MOST OF THE RESULTANT DEBRIS MOISTURE ADVECTED NE ACROSS THE E CARIBBEAN INTO THE SUBTROPICAL CENTRAL N ATLC. AT THE LOW LEVELS...A RIDGE EXTENDING ALONG 32N135W TO 25N130W TO 20N118W IS WEAKENING AND RETRACTING W WITH TIME. A LOW LEVEL REFLECTION OF THE UPPER CYCLONE IS ANALYZED AS A SURFACE TROUGH ALONG 124/125W FROM 30N TO 21N...AND DRIFTING W WITH TIME. THE GRADIENT N OF 26N BETWEEN THIS TROUGH AND RIDGE IS SUPPORTING N WINDS OF 20 KT AND SEAS TO 8 FT. THE TROUGH IS EXPECTED TO CONTINUE DRIFTING W OVER THE NEXT FEW DAYS WITH LITTLE CHANGE IN THE CONDITIONS W OF THE TROUGH. THE GRADIENT WILL ALSO TIGHTEN E OF THE TROUGH ALONG THE W COAST OF THE BAJA PENINSULA FROM 23N TO 27N TODAY SUPPORTING NW WINDS TO 20 KT WITH CONDITIONS CONTINUING THROUGH MIDDAY TUE. A SMALL AREA OF NE TRADES CURRENTLY TO 20 KT...SEAS TO 8 FT...ARE OBSERVED S OF THE RIDGE BUT ARE EXPECTED TO DIMINISH BELOW 20 KT LATER TONIGHT AS THE RIDGE WEAKENS. GAP WINDS...A BROAD TROUGH IS EXPECTED TO DOMINATE THE EASTERN GULF OF MEXICO...NW CARIBBEAN AND FLORIDA STRAITS OVER THE NEXT FEW DAYS WITH HIGH PRESSURE BUILDING IN THE WAKE OF A COLD FRONT OVER WESTERN GULF OF MEXICO. THESE FEATURES ARE CURRENTLY COMBINING TO DRIVE NORTHERLY 20 TO 25 KT WINDS INTO THE GULF OF TEHUANTEPEC. EXPECT THESE WINDS TO INCREASE TO 25 TO 30 KT LATER TODAY THROUGH AT LEAST LATE WED...WITH SOME GUIDANCE HINTING AT MINIMAL GALE BRIEFLY THIS EVENING AND OVERNIGHT. $$ STRIPLING