000 AXNT20 KNHC 031718 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON AUG 03 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 1600 UTC. ...TROPICAL WAVES... A TROPICAL WAVE HAS BEEN ADDED TO THE 1200 UTC ANALYSIS ALONG 19W/20W S OF 18N MOVING W NEAR 15 KT. THE UPPER-AIR TIME SECTION FROM DAKAR INDICATES THE WAVE PASSING NEAR 17.5W AROUND 0000 UTC ON 08/03. THIS WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM ON TOTAL PRECIPITABLE WATER IMAGERY. VISIBLE SATELLITE IMAGERY ALSO INDICATES LOW-LEVEL CYCLONIC FLOW NEAR THE VICINITY OF THE WAVE AXIS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 12N-16N BETWEEN 17W-21W. A TROPICAL WAVE EXTENDS ALONG 24N44W 18N43W 13N40W 8N40W MOVING W NEAR 15 KT. VISIBLE SATELLITE IMAGERY INDICATES A WELL-DEFINED INVERTED-V PATTERN IN THE LOW CLOUD STRUCTURE. THIS WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. A DRY SAHARAN AIR LAYER IS E OF THE WAVE AXIS INHIBITING ANY DEEP CONVECTION. A TROPICAL WAVE IS ALONG 62W S OF 18N MOVING W NEAR 15 KT. THE NORTHERN PORTION OF THIS WAVE HAS FRACTURED OFF TO FORM A TROUGH CURRENTLY W OF PUERTO RICO EXTENDING FROM 22N66W TO 18N68W. THIS WAVE LIES W OF A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THIS WAVE IS CURRENTLY UNDER AN AREA OF DRY AIR AND SUBSIDENCE ALOFT LIMITED ANY DEEP CONVECTION NEAR THE WAVE. A TROPICAL WAVE IS ALONG 97W S OF 22N MOVING W NEAR 20 KT. THIS WAVE IS WITHIN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. THE MAJORITY OF THIS WAVE LIES IN THE E PACIFIC...SEE THE TWDEP FOR MORE DETAILS. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 13N15W 9N28W 12N38W 10N50W 11N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-11N BETWEEN 26W-31W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF THE AXIS BETWEEN 46W-53W. ...DISCUSSION... THE GULF OF MEXICO... A BROAD SURFACE RIDGE WITH AXIS ALONG 28N COVERS THE MAJORITY OF THE GULF OF MEXICO BRINGING GENERALLY FAIR WEATHER ACROSS THE AREA. HOWEVER...ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE NRN GULF N OF 28N E OF 88W GENERATED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL RIDGE OVER THE MAJORITY OF THE GULF CENTERED OVER SRN TEXAS NEAR 28N98W AND AN UPPER LEVEL TROUGH OVER THE ERN CONUS. AN UPPER LEVEL TROUGH IS OVER THE SE GULF CENTERED AROUND AN UPPER LEVEL LOW S OF MEXICO NEAR 14N95W. A TROPICAL WAVE IS IN THE BAY OF CAMPECHE ALONG 97W...BUT NO SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH IT. ANTICYCLONIC SURFACE FLOW IS PRESENT AROUND THE SURFACE RIDGE WITH WINDS REACHING 15 KT ACROSS THE WRN GULF. EXPECT THE SURFACE RIDGE TO PERSIST...AND A WEAK FRONTAL TROUGH WILL DIP INTO THE EXTREME NE GULF TUE DISSIPATING BY WED. THE CARIBBEAN SEA... AN UPPER LEVEL TROUGH IS OVER THE NW CARIBBEAN CENTERED AROUND AN UPPER LEVEL LOW S OF MEXICO NEAR 14N95W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH AND THE UPPER LEVEL RIDGE OVER THE GULF OF MEXICO IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS OVER THE NW CARIBBEAN FROM 16N-22N BETWEEN 79W-89W. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN FROM 10N-13N W OF 82W INFLUENCED BY THE PROXIMITY OF THE E PACIFIC ITCZ. A SURFACE TROUGH IS JUST W OF PUERTO RICO EXTENDING FROM 18N68W INTO THE ATLC. THIS TROUGH FORMED AS A FRACTURED PORTION OF THE TROPICAL WAVE W OF THE LESSER ANTILLES ALONG 62W. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING SOME ISOLATED SHOWERS S OF THE HISPANIOLA N OF 17N BETWEEN 68W-70W. ELSEWHERE ACROSS THE CARIBBEAN...DRY AIR AND SUBSIDENCE ALOFT ARE SUPPORTING GENERALLY FAIR WEATHER AT THE SURFACE. FRESH TO STRONG TRADEWINDS ARE PRESENT ACROSS MUCH OF THE CARIBBEAN WITH THE STRONGEST WINDS NEAR THE COAST OF COLUMBIA. EXPECT THE TROPICAL WAVE ALONG 62W TO PROPAGATE WWD ACROSS THE CARIBBEAN. THE ATLANTIC OCEAN... SCATTERED SHOWERS/THUNDERSTORMS ARE OVER THE NW ATLC N OF 28N W OF 77W DUE TO SURFACE CONVERGENCE NEAR A SURFACE TROUGH N OF THE DISCUSSION AREA. THIS SHOWER ACTIVITY IS ALSO ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL RIDGE OVER THE GULF OF MEXICO AND THE UPPER LEVEL TROUGH OVER THE ERN CONUS. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO FROM 20N-30N BETWEEN 60W-70W. THIS ACTIVITY IS ENHANCED BY SURFACE CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM W OF PUERTO RICO NEAR 18N68W TO 22N66W...AND BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW NEAR 29N63W AND A BROAD UPPER LEVEL RIDGE COVERING THE TROPICAL ATLC. ELSEWHERE ACROSS THE ATLC...A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1029 MB SURFACE HIGH NEAR 36N50W BRINGING GENERALLY FAIR WEATHER ACROSS THE BASIN. ACROSS THE TROPICAL ATLC...A BROAD UPPER LEVEL RIDGE COVERS THE AREA S OF 25N CENTERED NEAR 18N43W ENHANCING CONVECTION ALONG THE ITCZ. $$ WALT0N