000 AXPZ20 KNHC 210324 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC WED OCT 21 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 0315 UTC. ...SPECIAL FEATURE... TROPICAL STORM RICK AT 20.9N 109.2W AT 0300 UTC OCT 21 OR 145 NM SSE OF CABO SAN LUCAS MEXICO AND ABOUT 240 NM SW OF MAZATLAN MEXICO. RICK IS MOVING NE OR 050 DEG AT 10 KT. ESTIMATED MINIMUM CENTRAL PRES 990 MB. MAXIMUM SUSTAINED WINDS ARE 55 KT WITH GUSTS TO 65 KT. SCATTERED STRONG THUNDERSTORMS ARE NOTED WITHIN 180 NM OF CENTER EXCEPT WITHIN 60 NM OVER THE SE QUADRANT. THERE IS POTENTIAL FOR THE HEAVY RAINFALL TO PRODUCE LIFE THREATENING FLASH FLOODS AND MUD SLIDES. RICK IS UNDERGOING CONTINUED SW WIND SHEAR AND IS EXPECTED TO WEAKEN SLIGHTLY BEFORE MOVING INLAND ON WED NIGHT OR THU MORNING. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... NONE. ...ITCZ... INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N78W TO 07N90W TO 15N110W TO 07N129W TO 08N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS NOTED FROM 05N TO 11N BETWEEN 77W AND 106W AND ALSO WITHIN 30 NM OF 13N106W AND ALSO WITHIN 60 NM EITHER SIDE OF A LINE FROM 15N109W TO 09N117W TO 09N123W TO 11N127W. ...DISCUSSION... AN UPPER LEVEL RIDGE IS COLLAPSING SE OVER THE EXTREME NW PORTION OF THE DISCUSSION AREA...GENERALLY TO THE N OF 25N W OF 130W. AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE DEEP TROPICS NEAR 11N126W WITH A RIDGE EXTENDING NW TO A CREST AT 16N134W WITH THE RIDGE NOW BEING ERODED BY AN UPPER TROUGH DESCRIBED BELOW. ITCZ CONVECTION ENHANCED EARLIER UNDER THE ANTICYCLONE IS DISSIPATING WITH THE DEBRIS MOISTURE REMAINING WITHIN 120 NM OF 10N125W. A THIRD UPPER ANTICYCLONE IS OVER TROPICAL CYCLONE RICK WITH A RIDGE EXTENDING NE AND AMPLIFYING OVER SW OKLAHOMA ATTM. DEBRIS MOISTURE FROM RICK IS ADVECTED NE ACROSS MOST OF OLD MEXICO N OF 20N...AND IS NOW SPREADING NE ACROSS ACROSS SOUTHER OKLAHOMA. BETWEEN THESE ANTICYCLONES IS THE SOUTHERN EXTENSION OF A LONG WAVE TROUGH THAT EXTENDS N TO S ACROSS N AMERICA ALONG ROUGHLY 105W THEN TURNS SW INTO THE DISCUSSION AREA ALONG 32N111W TO A BASE NEAR 19N124W. THE SOUTHWEST WINDS JUST AHEAD OF THIS TROUGH IS SHEARING TROPICAL STORM RICK. DRY UPPER AIR IS NOTED N OF 14N W OF 112W AND OVER THE DEEP TROPICAL PACIFIC S OF THE ITCZ W OF 115W. AN UPPER TROUGH EXTENDS S ACROSS THE NW CARIBBEAN TO NEAR 11N84W. BROAD UPPER RIDGING DOMINATES THE TROPICS ELSEWHERE S OF 15N E OF 105W ENHANCING ITCZ CONVECTION WITH THE RESULTANT DEBRIS MOISTURE SPREADING S TOWARDS THE EQUATOR. AT THE LOW LEVELS HIGH PRES IS CENTERED AT 32N140W WITH A RIDGE EXTENDING ESE TO NEAR 23N117W. THE GRADIENT E OF THE RIDGE HAS INCREASED THE NORTHERLY FLOW TO 20 KT OVER THE WATERS N OF 27N ALONG THE BAJA COAST. THE GRADIENT SW OF THE RIDGE IS SUPPORTING NE WINDS TO 20 KT FROM 11N TO 23N W OF 122W. N AND NW SWELLS ARE MIXING OVER THE SUBTROPICAL WATERS. SOUTHERLY SWELLS ARE CROSSING THE EQUATOR AND MIXING WITH THE NORTHERLY SWELLS BETWEEN 10N AND 20N. GAP WINDS... WINDS DECREASED BELOW GALE STRENGTH IN THE GULF OF TEHUANTEPEC THIS AFTERNOON WITH THE NORTHERLY FLOW EXPECTED TO FURTHER DIMINISH BELOW 20 KT WED AFTERNOON. $$ NELSON