000 AXNT20 KNHC 271803 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 27 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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... TROPICAL WAVE IS ALONG 31W/32W S OF 17N MOVING SLOWLY W. THIS WAVE HAS BECOME INCREASINGLY DIFFICULT TO LOCATE OVER THE PAST SEVERAL HOURS AS IT IS EMBEDDED IN A LARGER SCALE MONSOON TROUGH. THERE IS A SMALL CLUSTER OF MODERATE TO STRONG CONVECTION WITHIN 30NM EITHER SIDE OF THE AXIS FROM 13N-15N. THERE ARE SOME HINTS OF AN INVERTED V SIGNATURE IN THE STRATOCUMULUS FIELD A LITTLE FURTHER W FROM 14N-18N BETWEEN 33W-37W...WHICH MATCHES UP WELL WITH A POSITIVE MAXIMUM IN UW-CIMSS SATELLITE DERIVED 850 MB VORTICITY. THUS...THE WAVE MAY NEED TO BE NUDGED TO THE W A BIT ON THE 1800 UTC MAP. TROPICAL WAVE IS TILTED ALONG 16N45W 11N45W 6N47W MOVING W 5-10 KT. A 1012 MB LOW IS ATTACHED TO THE WAVE NEAR 12N. ISOLATED CLUSTERS OF MODERATE CONVECTION ARE WITHIN 250 NM EITHER SIDE OF THE AXIS MAINLY FROM 9N-15N. THIS WAVE REMAINS IDENTIFIABLE IN SSMI DERIVED TPW IN ADDITION TO CONVENTIONAL SATELLITE DATA. TROPICAL WAVE IS MOVING INTO THE WRN CARIBBEAN ALONG 78W S OF 19N MOVING W NEAR 20 KT. ISOLATED SHOWERS AND TSTMS ARE WITHIN 60NM W/120NM E OF THE AXIS FROM 15N-19N. THIS WAVE ALSO SHOWS UP WELL AS A POLEWARD INFLECTION OF HIGH MOISTURE IN SSMI DERIVED TPW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 10N20W 13N28W 11N38W 10N50W 9N63W. THE E ATLC PORTION OF THE AXIS IS RATHER ACTIVE THIS AFTERNOON WITH NUMEROUS MODERATE CONVECTION WITHIN 250NM S OF THE AXIS E OF 29W. LOW LEVEL FLOW IS ALSO HIGHLY SW TO W IN THIS VICINITY. METSAT-9 HOVMOLLER DIAGRAMS SUGGEST THE NEXT TROPICAL WAVE IS NEAR THE COAST OF AFRICA. THE RAOB FROM BAMAKO MALI ALSO SHOWED THE WAVE PASSAGE WELL YESTERDAY. SCATTERED MODERATE ALSO NOTED WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 36W-41W. ...DISCUSSION... GULF OF MEXICO... THE MAIN FOCUS CONTINUES TO BE THE MESSY WEATHER OFF THE COAST OF TEXAS AND LOUISIANA. AS OF 27/1500 UTC A 1012 MB LOW WAS OFF THE UPPER TEXAS COAST NEAR 29N95W. A TROUGH EXTENDS SSW FROM THE LOW TO NEAR BROWNSVILLE. RADAR...SATELLITE...AND LIGHTNING DATA DEPICT NUMEROUS SHOWERS AND TSTMS N OF 25N BETWEEN 88W-97W. THE LOW IS EXPECTED TO MOVE INLAND OVER THE NEXT DAY OR SO AND SIGNIFICANT DEVELOPMENT IS NOT EXPECTED. HOWEVER THE SYSTEM WILL PRODUCE LOCALLY HEAVY RAINFALL OVER PORTIONS OF SOUTHEASTERN TEXAS AND SOUTHERN LOUISIANA. SEE STATEMENTS FROM LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICES FOR ADDITIONAL INFORMATION. THIS ACTIVITY IS ALSO BEING LARGELY SUPPORTED BY THE UPPER LOW OVER CENTRAL TEXAS AND UPPER RIDGING EXTENDING E THROUGH THE CENTRAL GULF FROM MEXICO. ELSEWHERE AT THE SFC...A 1019 MB HIGH IS NEAR THE FLORIDA PANHANDLE. WEAK HIGH PRES EXPECTED TO REMAIN QUASI-STATIONARY OVER THE NE GULF THROUGH SAT. CARIBBEAN SEA... SCATTERED SHOWERS AND TSTMS ARE AGAIN OVER THE FAR SW CARIBBEAN IN RESPONSE TO LOW LEVEL SPEED CONVERGENCE DOWNSTREAM FROM THE MODERATE TO FRESH TRADES NEAR THE COLOMBIAN COAST. ASIDE FROM THIS AND THE FEW TSTMS WITH THE TROPICAL WAVE...THE CARIBBEAN IS PRETTY QUIET. UPPER NE FLOW AROUND RIDGING DOMINATES THE NW PORTION...AHEAD OF THE INVERTED UPPER TROUGHING EXTENDING NE FROM COSTA RICA TO NEAR HAITI. A WEAK UPPER HIGH NOTED NEAR THE ABC ISLANDS WHILE TROUGHING AND DRY UPPER AIR DOMINATES THE NE CARIB. MODERATE TRADES PERSIST THROUGH THE WEEKEND...STRONGEST IN THE CENTRAL PORTION. ATLANTIC OCEAN... SCATTERED SHOWERS AND TSTMS ARE CURRENTLY OVER THE EAST COAST OF SOUTH FLORIDA...BAHAMAS...AND WRN ATLC W OF 76W. THIS REGION IS UNDER STRONG UPPER DIFFLUENCE BETWEEN LARGE SCALE TROUGHING OVER THE EAST COAST AND RIDGING EXTENDING E FROM THE GULF ALONG 26N OUT TO NEAR 70W. A SFC TROUGH ALSO ENTERS THE W ATLC NEAR 30N72W AND CONTINUES S TO 24N73W. LOW CLOUD MOTIONS SHOW CLEAR CYCLONIC TURNING IN THE VICINITY...WITH ASSOCIATED SCATTERED SHOWERS/ISOLATED TSTMS FROM 23N-27N BETWEEN 68W-75W. AN UPPER LOW HAS REMAINED QUASI STATIONARY NEAR 28N60W. A SFC TROUGH IS ALSO ANALYZED IN THIS VICINITY ALONG 31N55W 26N60W. LIGHTNING DATA SUGGESTS MOST OF THE ASSOCIATED TSTMS ARE CONFINED TO THE REGION FROM 23N-27N BETWEEN 57W-62W. LARGE SCALE UPPER RIDGING AND ABUNDANT DRY/STABLE AIR DOMINATES MUCH OF THE E ATLC. A SFC RIDGE ANCHORED BY A 1023 MB HIGH NEAR 33N40W ALSO DOMINATES THE E ATLC. THE COMBINATION OF THESE FEATURES HAVE LED TO WIDESPREAD FAIR WEATHER AND LIGHT TO MODERATE TRADES N OF 15N W OF 50W. $$ WILLIS