000 AXNT20 KNHC 281752 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 28 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1730 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 31W/32W SOUTH OF 17N MOVING WEST NEAR 16 KT. THIS WAVE CONTINUES TO SHOW BROAD LOW-MID LEVEL CURVATURE. LOW LEVEL CONVERGENCE AND ASSOCIATED CONVECTION IS STRONGEST WEST OF THE WAVE AXIS EMBEDDED IN THE ITCZ WHERE THERE IS SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 5N TO 12N BETWEEN 36W AND 45W. A TROF HAS BEEN ADDED ALONG THIS FEATURE ALONG A LINE EXTENDING NE FROM 5N40W TO NEAR 9N36W DUE TO AFTERNOON CLOUD MOTION ANALYSIS AND RECENT SHIP OBSERVATIONS SHOWING A CYCLONIC WIND FIELD. SOME SLOW DEVELOPMENT IS POSSIBLE WITH THIS WAVE AS IT PROGRESSES WESTWARD OVER THE NEXT FEW DAYS. A TROPICAL WAVE IS ALONG 55W/56W SOUTH OF 21N MOVING QUICKLY WEST 20 TO 25 KT. SURFACE OBSERVATIONS AT BARBADOS OVER THE PAST 12 HRS SHOW A CLASSIC EASTERLY WAVE WIND SHIFT...WITH ENE THEN E WINDS LATE LAST NIGHT AND EARLY THIS MORNING SHIFTING MORE SE AFTER 14/15Z SUGGESTING THE WAVE HAS RECENTLY MOVED THROUGH THE AREA. IT IS UNCLEAR...HOWEVER...IF SOME OF THIS VEERING IS DUE TO THE LOCAL SEA BREEZE CIRCULATION. THE WAVE SHOWS A DEFINITE INVERTED V SHAPE AND LOW LEVEL CYCLONIC TURNING AROUND ITS AXIS. SCATTERED MODERATE CONVECTION ASSOCIATED WITH THIS WAVE IS SPREADING THROUGH THE LESSER ANTILLES FROM 12N TO 18N BETWEEN 58W AND 66W. THE WAVE WILL CONTINUE SPREADING SHOWERS AND THUNDERSTORMS WESTWARD THROUGH THE CARIBBEAN SEA AND SURROUNDING ISLANDS OVER THE WEEKEND. A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 73W SOUTH OF 24N MOVING WEST NEAR 15 KT. THIS WAVE CONTINUES TO INTERACT WITH AN UPPER TROUGH EXTENDING NE FROM THE BAHAMAS/TURKS AND CAICOS AND IS PRODUCING PATCHES OF SCATTERED MODERATE CONVECTION WITHIN 250 NM EITHER SIDE OF THE ANALYZED WAVE AXIS. CONVECTION PULSED STRONGER NEAR THE WAVE AXIS THIS MORNING SOUTH OF HISPANIOLA FROM 13 TO 18N AND BETWEEN 70W AND 74W...WITH A NOTED OUTFLOW BOUNDARY SEEN SPREADING RADIALLY OUTWARD FROM THE CONVECTIVE COMPLEX ON VISIBLE IMAGERY FROM 13 TO 16Z. THE NW PORTION OF THE OUTFLOW BOUNDARY HAS SINCE PUSHED ASHORE THE S COAST OF HAITI AND THE CONVECTION HAS BEEN TRENDING WEAKER OVER THE PAST FEW HOURS. GFS SEEMS TO HAVE A DECENT HANDLE ON THE MOISTURE ASSOCIATED WITH THIS WAVE...AND SEEMS TO MOVE A HEAVILY SHEARED AND THUS WEAKER NORTHERN PORTION OF MOISTURE AND INSTABILITY THROUGH THE BAHAMAS AND FLORIDA LATER TONIGHT AND TOMORROW WHILE THE CENTRAL/SOUTHERN AND POTENTIALLY MORE ACTIVE EXTENT OF THE WAVE CONTINUING TO PROGRESS WESTWARD INTO THE WESTERN CARIBBEAN. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 17N15W 11N30W 7N42W 11N54W TO INLAND OVER SOUTH AMERICA NEAR 9N61W TO PUERTO LIMON COSTA RICA NEAR 10N83W. BESIDES FOR THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES...THE CLUSTER OF MODERATE CONVECTION THAT MOVED OFF THE COAST OF AFRICA E OF 17W FROM 13N-18N EARLIER TODAY HAS SINCE DIMINISHED IN BOTH COVERAGE AND INTENSITY. SCATTERED MODERATE CONVECTION IS ACROSS SOUTH AMERICA ENHANCED BY THE CENTRAL CARIBBEAN WAVE FROM 2N-10N BETWEEN 69W-74W. A PATCH OF MODERATE CONVECTION LIES JUST NORTH OF THE AXIS OFF THE CENTRAL CARIBBEAN COAST OF NICARAGUA...DUE SOUTH OF THIS AREA LIES ANOTHER PATCH OF SCATTERED MODERATE CONVECTION SOUTH OF MAL PIAS COSTA RICA TO 6N THAT IS MOVING INTO THE EAST PACIFIC. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR LOOP SHOWS EASTERLY FLOW BLANKETING THE ENTIRE GULF OF MEXICO THIS AFTERNOON BETWEEN AN UPPER HIGH CENTERED JUST WEST OF GALVESTON TEXAS AND AND UPPER TROF SPINNING AROUND THE YUCATAN PENINSULA. ANOTHER UPPER LOW IS SEEN IN WV IMAGERY OVER CENTRAL FLORIDA WITH ITS CENTER APPROACHING TAMPA. UPPER DIFFLUENCE BETWEEN THESE FEATURES ALONG WITH THE UPPER HIGH IN THE WESTERN CARIBBEAN IS PRODUCING SCATTERED MODERATE CONVECTION THROUGH TH FLORIDA STRAITS AND INTO THE SW GULF AND SOUTH CENTRAL FLORIDA FROM 23N TO 27N BETWEEN 78W AND 86W. MINIMAL SHOWER/THUNDERSTORM ACTIVITY NOTED IN THE CENTRAL AND WESTERN GULF THIS AFTERNOON. AT THE SURFACE...THE WESTERN EXTENSION OF THE BERMUDA HIGH LIES ACROSS THE GULF WITH MODEST 5-15KT E/SE FLOW DOMINATING AND OVERALL NOT MUCH IS EXPECTED TO CHANGE WITH THIS FLOW THROUGH THE WEEKEND. HOWEVER...MOISTURE ASSOCIATED WITH THE TROPICAL WAVE IN THE CENTRAL CARIBBEAN ALONG 73W MAY INCREASE PRECIP/THUNDER CHANCES OVER THE GULF OVER THE WEEKEND...AND FROM THE WAVE THAT MOVED THROUGH BARBADOS THIS MORNING EARLY TO MID NEXT WEEK. CARIBBEAN SEA... THE MAIN FEATURE IN THE REGION IS THE SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE MOVING WEST FROM ITS 12Z ANALYZED POSITION ALONG 73W. SCATTERED MODERATE CONVECTION IS ALSO SPREADING THROUGH THE LESSER ANTILLES AND THE EASTERN CARIBBEAN WITH THE NEXT TROPICAL WAVE WHICH IS NOW BEGINNING TO MOVE INTO THE CARIBBEAN. AN UPPER LEVEL HIGH IS NOTED IN THE WESTERN CARIBBEAN...CENTERED NEAR 17N84W. ANOTHER UPPER HIGH IS EXTENDING INTO THE WEST AND CENTRAL CARIBBEAN FROM THE TROPICAL ATLANTIC WHICH IS CENTERED NEAR 20N61W. UPPER TROUGHING CONTINUES TO DOMINATE THE AREA EXTENDING NE FROM THE SE BAHAMAS AND TURKS AND CAICOS ISLANDS...WITH THE SOUTH EXTENT OF THIS TROF AFFECTING THE NORTHERN CARIBBEAN. PRONOUNCED UPPER DIFFLUENCE BETWEEN THIS FEATURES AND ABOVE THE TROPICAL WAVE IN THE CENTRAL CARIBBEAN AIDING IN THE CONVECTION AS DESCRIBED ABOVE. 10-20KT TRADE WINDS PREVAIL OVER MUCH OF THE CARIBBEAN ON THE S/SW SIDE OF THE BERMUDA SFC HIGH. SIMILAR CONDITIONS GENERALLY EXPECTED THROUGH THE WEEKEND ALTHOUGH GUSTIER WINDS AND SHOWERS/THUNDERSTORMS EXPECTED IN THE VICINITY OF THE TROPICAL WAVES MOVING THROUGH. ATLANTIC OCEAN... LARGE SCALE UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE ATLC WATERS TODAY...WITH A SERIES OF FOUR SHORT WAVE RIDGES NOTED IN WV IMAGERY FROM 13N TO 26N BETWEEN 17W AND 67W...WITH NEARLY ALL OF THIS REGION SHOWING FAIR/DRY WEATHER WITH MINIMAL SHOWER ACTIVITY NOTED. MUCH OF THIS REGION IS ALSO HOVERED BY A DENSE LAYER OF SAHARAN DUST. JUST WEST OF THIS REGION LIES AN UPPER TROF EXTENDING NE FROM THE BAHAMAS AND TURKS AND CAICOS ISLANDS. THE DISTURBED WEATHER/CONVECTION WEST OF THE TROPICAL WAVE ALONG 32W/ABOUT 1000 MILES WSW OF THE CAPE VERDE ISLANDS HAS POTENTIAL FOR SLOW DEVELOPMENT...THOUGH COMPUTER MODEL GUIDANCE IS NOT SUGGESTING MUCH AT THIS TIME. AT THE SURFACE...A 1029MB HIGH IS EXTENDING INTO THE TROPICAL ATLANTIC FROM ITS CENTER NEAR 33N55W. GUIDANCE SUGGESTS THIS HIGH WILL GRADUALLY WEAKEN AS WE MOVE THROUGH THE WEEKEND. $$ WILLIS