000 AXNT20 KNHC 052354 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE SEP 05 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURE... FLORENCE...THE SIXTH NAMED STORM OF THE 2006 TROPICAL SEASON IS CENTERED NEAR 17.4N 48.5W OR ABOUT 960 MILES EAST OF THE NORTHERN LEEWARD ISLANDS AT 05/2100Z. IT IS MOVING WNW AT 12 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. FLORENCE IS GETTING A LITTLE STRONGER OVER THE OPEN ATLANTIC. THE LOW-LEVEL CIRCULATION CENTER...AS WELL AS CONVECTIVE BANDING FEATURES HAS BECOME BETTER DEFINED IN VISIBLE SATELLITE IMAGERY. THUNDERSTORM ACTIVITY HAS ALSO BEGUN TO DEVELOP IN THE INNER CORE REGION. A CLUSTER OF MODERATE TO STRONG CONVECTION IS FROM 17N-20N BETWEEN 44W-47W. THIS TROPICAL CYCLONE WILL CONTINUE TO MOVE ON A GENERAL WEST-NORTHWESTWARD MOTION THROUGH 96 HOURS...REMAINING OVER THE WARM OCEAN WATERS. IT IS FORECAST TO REACH MINIMAL HURRICANE INTENSITY ON FRIDAY. ...TROPICAL WAVES... AN E ATLC TROPICAL WAVE IS ALONG 33W SOUTH OF 21N...SEVERAL HUNDRED MILES WEST OF THE CAPE VERDE ISLANDS. SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS SYSTEM CONTINUE TO SHOW SIGNS OF ORGANIZATION. ENVIRONMENTAL CONDITIONS APPEAR SOMEWHAT FAVORABLE FOR A TROPICAL DEPRESSION TO DEVELOP DURING THE NEXT COUPLE OF DAYS AS THE SYSTEM MOVES WESTWARD AT ABOUT 10 MPH. A HIGH-AMPLITUDE TROPICAL WAVE IS ALONG 60/61W SOUTH OF 23N MOVING W NEAR 10 KT. THIS WAVE CONTINUES TO SHOW A WELL DEFINED INVERTED V CLOUD PATTERN. A MOIST ELY SURGE JUST AHEAD OF THIS SYSTEM IS GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER THE EASTERN CARIBBEAN...INCLUDING THE VIRGIN ISLANDS AND PARTS OF PUERTO RICO. THIS WAVE WILL MOVE ACROSS THE VIRGIN ISLANDS AND PUERTO RICO TONIGHT TROUGH WEDNESDAY BRINGING A NOTICEABLE INCREASE IN SHOWER AND TSTM ACTIVITY. THE SAN JUAN DOPPLER RADAR IS ALREADY SHOWING BAND OF SHOWERS WITH EMBEDDED TSTM MOVING WWD ACROSS THESE ISLANDS. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W SOUTH OF 21N MOVING WEST NEAR 10 KT. A NARROW UPPER TROUGH IN THE AREA IS MASKING THE LOW-LEVEL SIGNATURE. SOME POSSIBLE INTERACTION FROM THIS WAVE AND THE UPPER TROUGH IS TRIGGERING SCATTERED SHOWERS AND TSTMS OVER JAMAICA AND EASTERN CUBA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 10N30W 12N40W 10N50W 11N59W. OUTSIDE THE CONVECTION ASSOCIATED WITH TROPICAL STORM FLORENCE AND THE TROPICAL WAVES...A CLUSTER OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS MOVING OUT OF AFRICAN COAST FROM 10N-14N E OF 17W. ...DISCUSSION... THE GULF OF MEXICO... A MID-UPPER LOW SITUATED OVER THE EASTERN GULF NEAR 23N89W IS PRODUCING A BROAD AREA OF SHOWERS AND TSTMS OVER THE YUCATAN PENINSULA AND NORTHERN GUATEMALA. AN UPPER HIGH IS ANCHORED OVER NW MEXICO WITH A RIDGE EXTENDING NEWD ACROSS THE SOUTH U.S. AND THE NORTHERN GULF WATERS. THE RIDGE ALSO COVERS A GOOD PORTION OF MEXICO. ABUNDANT UPPER LEVEL MOISTURE COVERS THE AREA FROM TEXAS TO GEORGIA AND MOST OF THE GULF. AS OF 2100 UTC...A BROAD SURFACE TROUGH EXTENDS ALONG 27N84W 22N86W 17N90W. THIS TROUGH AND A DIFFLUENT PATTERN ALOFT ARE KEEPING SOUTH-CENTRAL FLORIDA IN A VERY WET ENVIRONMENT. A STATIONARY FRONT EXTENDS FROM SE LOUISIANA TO NE MEXICO. A PRE-FRONTAL SFC TROUGH LIES ABOUT 100 NM SE OF THE FRONT FROM 27N88W TO 24N96W. A NARROW LINE OF CLOUDS AND ISOLATED SHOWERS IS ASSOCIATED WITH THE FRONTAL BOUNDARY WHILE SCATTERED SHOWERS AND TSTM ARE WITHIN 60 NM AHEAD OF THE TROUGH. A MOIST AND UNSTABLE ATMOSPHERE WILL PERSIST OVER SOUTH-CENTRAL FLORIDA TONIGHT AND TOMORROW. THE CARIBBEAN SEA... AN UPPER TROUGH EXTENDS FROM THE SE BAHAMAS ACROSS E CUBA AND JAMAICA TO NEAR CABO GRACIAS A DIOS NICARAGUA. THIS TROUGH ALONG WITH A TROPICAL WAVE IS SUPPORTING THE DEVELOPMENT OF SCATTERED SHOWERS AND TSTM OVER E CUBA...JAMAICA AND PARTS OF NICARAGUA AND HONDURAS. SIMILAR CONVECTIVE ACTIVITY IS OVER COSTA RICA AND PANAMA DUE TO THE CLOSE PROXIMITY OF THE ITCZ. AN UPPER HIGH LOCATED OVER PUERTO RICO DOMINATES THE EASTERN CARIBBEAN. THIS FEATURE IS ALSO ENHANCING THE SHOWER/TSTM ACTIVITY OVER THE AREA. A NEW CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION HAS DEVELOPED OVER NW VENEZUELA NEAR THE LAKE MARACAIBO AREA PROBABLY ASSOCIATED WITH THE ITCZ. TRADE WINDS ARE GENERALLY IN THE 15-20 KT RANGE E OF 80W...LIGHTER WINDS W OF THERE. THE ATLANTIC OCEAN... A BROAD TROUGH OF LOW PRESSURE NEAR FLORIDA IS PRODUCING A LARGE AREA OF SHOWERS AND THUNDERSTORMS OVER THE NORTHWESTERN BAHAMAS...FLORIDA AND THE ADJACENT WATERS. THUNDERSTORM ACTIVITY REMAINS DISORGANIZED AND DEVELOPMENT...IF ANY...IS EXPECTED TO BE SLOW TO OCCUR AS THE SYSTEM MOVES SLOWLY NORTH-NORTHEASTWARD. AN UPPER TROUGH IS OVER THE W ATLC W OF 70W. CONSIDERABLE MOISTURE LIES UNDER THE INFLUENCE OF THIS TROUGH. AN UPPER LEVEL HIGH IS CENTERED TO THE NE OF THE TROUGH NEAR 32N65W. ANOTHER UPPER HIGH IS OVER PUERTO RICO. A DEEP LAYER TROUGH REMAINS OVER THE CENTRAL ATLC...GENERATING MODERATE SWLY VERTICAL WIND SHEAR OVER T.S. FLORENCE AND LIMITING THE DEVELOPMENT OF THIS TROPICAL CYCLONE. THE ASSOCIATED FRONTAL BOUNDARY ENTERS THE AREA NEAR 31N34W AND EXTENDS SW TO 26N60W. A CUT-OFF UPPER LEVEL LOW APPEARS TO BE DEVELOPING NEAR THE TAIL END OF THE SFC FRONT ENHANCING SOME SHOWER ACTIVITY FROM 23N-28N BETWEEN 49W-59W. FARTHER EAST...A BROAD MID-UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE REGION WITH THE MAIN HIGH CENTER NEAR 21N31W. THE CIMSS SAL TRACKING PRODUCT SHOWS THAT A NEW SURGE OF AFRICAN DUST HAS PUSHED OFF THE COAST SPREADING TO ABOUT 30W. $$ GR