000 AXNT20 KNHC 131800 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED MAY 13 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... THE FIRST ANALYZED TROPICAL WAVE OF 2009 HAS BEEN ADDED TO THE 13/1200 UTC MAP ALONG 17W/18W MOVING W NEAR 15 KT. RECENT TIME-HEIGHT ANALYSES FROM BAMAKO INDICATE MEAN SFC-650 MB WINDS VEERED FROM NE TO SE IN CONJUNCTION WITH AN ORGANIZED AREA OF DEEP MOIST CONVECTION THAT MOVED OFF THE AFRICAN COAST DURING THE LAST DAY. THIS WIND SHIFT AT BAMAKO OCCURRED ON MAY 12 2009. TIME-HEIGHT ANALYSES FROM BAMAKO ALSO INDICATE LOW-TO-MID LEVEL MOISTURE MAXIMIZED AFTER THE PASSAGE OF THE TROPICAL WAVE. ALSO...THE WAVE COINCIDES WITH A WESTWARD-MOVING DEEP LAYER MOISTURE MAXIMUM AS INDICATED IN THE MIMIC TPW PRODUCT FROM CIMSS. METSAT-9 VISIBLE SATELLITE IMAGERY INDICATES CONTINUED LOW-LEVEL CYCLONIC TURNING...THOUGH RECENT QUIKSCAT IMAGERY INDICATES THAT CURVATURE VORTICITY HAS DIMINISHED NEAR THE WAVE AS IT BECOMES ABSORBED IN STRONGER NORTHERLY FLOW. DESPITE THE TEMPORARY LOSS IN CURVATURE VORTICITY AT THE SURFACE...REGIONAL VARIATIONS IN WIND SPEED AT THE SURFACE ARE MAINTAINING POSITIVE SURFACE VORTICITY NEAR THE WAVE. MUCH OF THE CONVECTION ASSOCIATED WITH THE WAVE HAS DIMINISHED...WITH SCATTERED MODERATE CONVECTION FROM 1N-7N BETWEEN 14W-22W. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 4N19W 1N26W 1N38W CROSSING THE EQUATOR NEAR 46W EXTENDING TO NE BRAZIL NEAR 1S50W. SCATTERED MODERATE CONVECTION IS S OF 3N BETWEEN 8W-10W AND S OF 3N BETWEEN 22W-29W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE OVER THE WRN GULF IS ADVECTING SOME TROPICAL MOISTURE FROM THE PACIFIC INTO THE REGION W OF 90W. THIS MOISTURE IS MAINLY IN THE FORM OF MID-HIGH LEVEL CLOUDINESS...THOUGH THERE COULD BE SOME EMBEDDED ISOLATED SHOWERS. SCATTERED SHOWERS ARE MOVING THROUGH THE STRAITS OF FLORIDA AND FAR SE GULF DRIVEN BY MOIST E/SE LOW-LEVEL FLOW. ELSEWHERE...MAINLY FAIR WEATHER DOMINATES THE AREA. BUOY/SHIP OBS AND SCATTEROMETER DATA SHOWS THE STRONGEST WINDS OVER THE WRN WATERS...SE 15-20 KT...DUE TO THE TIGHTENED PRESSURE GRADIENT BETWEEN HIGH PRES OVER NEW ENGLAND AND BROAD TROUGHING OVER THE S CENTRAL CONUS/MEXICO. CARIBBEAN SEA... BROAD RIDGING ALOFT COVERS THE SE HALF OF THE CARIBBEAN. UPPER LEVEL DIFFLUENCE BETWEEN THE RIDGE AND A TROUGH OVER THE NW CARIBBEAN AND EPAC IS SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS THE SW CARIBBEAN S OF 11N INCLUDING ADJACENT PORTIONS OF PANAMA AND COSTA RICA. HOWEVER...SUBSTANTIALLY MORE CONVECTIVE ACTIVITY IS FOUND OVER THE NEARBY E PAC WATERS S OF PANAMA AND COSTA RICA...WHERE LOW-LEVEL CONVERGENCE ALONG THE ITCZ IS AN ENHANCING FACTOR. MEANWHILE...SURFACE HIGH PRESSURE N OF THE CARIBBEAN SEA IS RESULTING IN FRESH E TRADE WINDS. THESE FRESH E TRADE WINDS ARE FORECAST TO PERSIST THROUGH THE WEEK. THE STRONGEST WINDS ARE FOUND NEAR THE COAST OF COLOMBIA...WHERE A 13/1200 UTC QUIKSCAT PASS SHOWS NE TO E 20-25 KT WINDS. POCKETS OF LOW LEVEL MOISTURE AND ISOLATED SHOWERS ARE BEING ADVECTED W ACROSS THE CARIBBEAN...WITH THE GREATEST CONCENTRATION OF THESE SHOWERS WITHIN 90 NM EITHER SIDE OF A SURFACE TROUGH OVER THE NE CARIBBEAN THAT EXTENDS FROM S HISPANIOLA NEAR 18N71W ACROSS THE N CARIBBEAN TO 16N71W. SURFACE OBSERVATIONS CONTINUE TO INDICATE A WEAK CYCLONIC WIND SHIFT IN THE VICINITY OF THIS TROUGH. ACROSS THE NW HALF OF THE CARIBBEAN...DEEP LAYER DRY AIR IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. DURING THE NEXT FEW DAYS...THE TRADE WINDS WILL GRADUALLY DIMINISH AS THE SURFACE HIGH OVER THE CENTRAL ATLC MOVES NE AND A BROAD SURFACE TROUGH DEVELOPS OVER THE GULF OF MEXICO THIS WEEKEND. ATLANTIC OCEAN... A SURFACE RIDGE ASSOCIATED WITH A 1029 MB SURFACE HIGH OVER THE CENTRAL ATLC NEAR 33N36W IS AFFECTING MUCH OF THE ATLC PORTION OF THE DISCUSSION AREA. SUBSIDENCE ASSOCIATED WITH THE SURFACE RIDGE IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF THE ATLC PORTION OF THE DISCUSSION AREA. HOWEVER... POCKETS OF LOW LEVEL MOISTURE WITH ISOLATED SHOWERS ARE MOVING W ACROSS PORTIONS OF THE SW NORTH ATLC. THE GREATEST CONCENTRATION OF THESE SHOWERS IS LOCATED WITHIN 90 NM EITHER SIDE OF A SURFACE TROUGH THAT EXTENDS FROM 22N68W TO N HISPANIOLA NEAR 20N70W. THIS TROUGH WILL CONTINUE MOVING W NEAR 15 KT AS IT AFFECTS THE GREATER ANTILLES DURING THE NEXT FEW DAYS. ALSO...ATMOSPHERIC LIFT ASSOCIATED WITH A MID/UPPER-LEVEL TROUGH OVER THE W ATLC IS SUPPORTING A COLD FRONT FROM 32N60W TO 30N72W WITH A STATIONARY FRONT EXTENDING FROM 30N72W TO A 1020 MB SURFACE LOW NEAR 30N75W. WINDS OF 20-25 KT ARE WITHIN 90 NM IN THE N SEMICIRCLE OF THE LOW WITH NE TO E WINDS TO 20 KT N OF THE FRONT AS THE LOW TRACKS NW TOWARD THE SURFACE RIDGE AXIS. LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS ALONG AND WITHIN 90 NM EITHER SIDE OF THE FRONTS. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT WITH AN AXIS EXTENDING FROM 13N16W TO 2N48W WITH AN UPPER HIGH CENTERED NEAR 9N27W. ASSOCIATED UPPER LEVEL DIVERGENCE IS ENHANCING ITCZ CONVECTION. $$ COHEN/CANGIALOSI