000 AXNT20 KNHC 101804 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN AUG 10 2008 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. ...SPECIAL FEATURES... SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A TROPICAL WAVE LOCATED OVER THE CENTRAL ATLANTIC ALONG 42W/43W OR ABOUT 980 NM EAST OF THE WINDWARD ISLANDS HAVE BECOME A LITTLE BETTER ORGANIZED THIS MORNING. SAT IMAGERY SHOWS SCATTERED TO ISOLATED STRONG CONVECTION WITHIN AROUND 150 NM W SEMICIRCLE OF A 1009 MB LOW EMBEDDED ON THE WAVE AXIS NEAR 10.5N 43.0W. CONDITIONS APPEAR SOMEWHAT FAVORABLE FOR GRADUAL DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 15 TO 20 MPH. ...TROPICAL WAVES... A NEW TROPICAL WAVE HAS BEEN ADDED TO THE 1200 UTC MAP BASED ON SATELLITE IMAGERY...OBSERVATIONS AND THE DAKAR VERTICAL SOUNDING WHICH REVEALS THAT THE LOW LEVEL WINDS HAVE VEERED OUT TO THE SOUTH INDICATING THE PASSAGE OF THE WAVE AXIS OVERNIGHT. THE WAVE AXIS IS ALONG 18W SOUTH OF 17N MOVING W 10-15 KT. SOME CYCLONIC TURNING IS SEEN ALON THE WAVE AXIS NEAR 12N WITH MODERATE TO STRONG CONVECTION WELL AHEAD OF THE WAVE LINE FROM 10N-14N BETWEEN 20W-25W. A TROPICAL WAVE IS ALONG 62W/63W S OF 18N MOVING W 15-20 KT. THE WAVE CONTINUES TO SHOW A NARROW NORTH-SOUTH MOISTURE MAXIMUM ON THE MIMIC-TPW PRODUCT. NO DEEP CONVECTION IS OBSERVED WITH SCATTERED SHOWERS NEAR THE N END OF THE WAVE AXIS...AND OVER TRINIDAD AND TOBAGO ISLANDS. A SURGE OF AFRICAN DUST FOLLOWS THIS WAVE. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ALONG 73W S OF 20N MOVING W NEAR 15 KT. THE WAVE SHOWS AN INVERTED-V SIGNATURE ON VIS SATELLITE IMAGERY ACROSS THE CARIBBEAN SEA WATERS. NO DEEP CONVECTION IS OBSERVED WITH THE WAVE...HOWEVER SCATTERED SHOWERS ARE OVER HISPANIOLA AND NEAR THE VENEZUELA/COLOMBIA BORDER. ...THE ITCZ... THE ITCZ IS PRETTY ACTIVE THIS MORNING. ITS AXIS IS CENTERED ALONG 12N17W 11N25W 12N37W 9N43W 8N59W. OUTSIDE OF THE CONVECTION ASSOCIATED WITH TWO TROPICAL WAVES...THERE IS AN AREA OF SCATTERED MODERATE CONVECTION FROM 10N-14N BETWEEN 29W-35W. THIS DISORGANIZED AREA OF DISTURBED WEATHER HAS SOME POTENTIAL FOR SLOW DEVELOPMENT DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT ABOUT 15 MPH. MODERATE CONVECTION IS ALSO NOTED WITHIN 100 NM N OF AXIS BETWEEN 50W-54W. ...DISCUSSION... GULF OF MEXICO... AN UPPER-LEVEL HIGH CENTERED OVER WEST TEXAS EXTENDS A RIDGE OVER THE N GULF WATERS MAINLY N OF 24N. AN UPPER-LEVEL TROUGH LIES JUST SOUTH OF THE RIDGE AND EXTENDS FROM THE W ATLC THROUGH SOUTH FLORIDA INTO THE GULF REGION ALONG 22N TO AN UPPER-LEVEL LOW CENTERED OVER CENTRAL MEXICO. THIS TROUGH SUPPORTS A WEAKENING STATIONARY FRONT WHICH CROSSES CENTRAL FLORIDA THEN CONTINUES NW TO SE LOUISIANA. SCATTERED SHOWERS AND TSTMS ARE AHEAD OF THE FRONTAL BOUNDARY AFFECTING THE EAST GULF E OF 85W AND SOUTH-CENTRAL FLORIDA. THE FRONT IS FORECAST TO DISSIPATE LATER TODAY. A RIDGE ANCHORED ON A 1018 MB HIGH OVER WESTERN CUBA DOMINATES THE REMAINDER OF THE GULF. SURFACE CIRCULATION AROUND THIS HIGH IS PROVIDING THE WRN AND CENTRAL GULF LIGHT SOUTHERLY RETURN FLOW...BUT THESE WINDS ARE EXPECTED TO INCREASE ON TUE AS A LOW PRES SYSTEM DEVELOPS OVER TEXAS AND NE MEXICO. CARIBBEAN SEA... AN UPPER-LEVEL LOW HAS BEEN MEANDERING OVER CUBA DURING THE LAST TWO OR THREE DAYS ENHANCING CONVECTION EVERY AFTERNOON. THE CYCLONIC FLOW COVERS THE NW CARIBBEAN AND EXTENDS EWD OVER HISPANIOLA. UPPER DIFFLUENCE BETWEEN THIS LOW AND A RIDGE WHICH COVERS THE YUCATAN PENINSULA AND N CENTRAL AMERICA IS SUPPORTING SOME SHOWER/TSTM ACTIVITY S OF THE CAYMAN ISLANDS AND OVER THE SW CARIBBEAN. THIS UPPER-LEVEL FEATURE IS ALSO AIDING IN GENERATING SCATTERED MODERATE CONVECTION ACROSS PANAMA...NRN COLOMBIA AND ADJACENT COASTAL WATERS S OF 10N. MODERATE TO STRONG SUBSIDENCE AND DRY AIR IS IN CONTROL ACROSS THE THE ERN AND CENTRAL CARIBBEAN SEA. MODERATE TO STRONG EASTERLY TRADE WINDS ARE BLOWING ACROSS THE BASIN WITH THE STRONGEST WINDS OFFSHORE OF THE NRN COLOMBIAN COAST. TWO TROPICAL WAVES ARE MOVING WWD ACROSS THE BASIN. SEE TROPICAL WAVE SECTION. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS LOCATED OVER THE ERN U.S. INTO THE FAR W ATLC WITH THE ASSOCIATED STATIONARY FRONTAL BOUNDARY ENTERING THE AREA NEAR 31N72W EXTENDING ACROSS CENTRAL FLORIDA AND INTO THE GULF OF MEXICO TO SE LOUISIANA. AN UPPER RIDGE IS TO THE SE CENTERED NEAR 26N70W. A DIFFLUENT PATTERN ALOFT BETWEEN THIS HIGH THE UPPER-LEVEL LOW SPINNING OVER E CUBA IS HELPING TO INDUCE SCATTERED SHOWERS AND TSTMS OVER THE NW BAHAMAS AND COASTAL WATERS. A SHORT-WAVE TROUGH IS JUST TO THE EAST ALONG 62W AND IS GENERATING A NARROW BAND OF SHOWERS WITH EMBEDDED TSTMS ALONG 32N62N 27N65W 24N67W. ELSEWHERE AN UPPER LOW IS OVER THE CENTRAL ATLC NEAR 26N47W WITH ANOTHER WEAK UPPER-LEVEL LOW OVER THE ERN ATLC NEAR 28N26W WITH TROUGHING EXTENDING SW TO ANOTHER UPPER LOW CENTERED NEAR 22N35W. AN UPPER-LEVEL HIGH IS SITUATED NEAR 22N20W EXTENDING A RIDGE ACROSS THE DEEP TROPICS. THIS UPPER SYSTEM IS ENHANCING CONVECTION ALONG THE ITCZ. OTHERWISE...THE ATLANTIC FORECAST AREA IS DOMINATED BY A 10125 SFC HIGH CENTERED NEAR 33N46W. THIS HIGH EXTENDS A RIDGE TO THE NE CARIBBEAN AND WILL REMAIN NEARLY STATIONARY DURING THE NEXT 24 HOURS OR SO. $$ GR