000 AXNT20 KNHC 292314 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN JUN 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2245 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 33W/34W S OF 13N MOVING W 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ WITH NO ORGANIZED DEEP CONVECTION OBSERVED. A TROPICAL WAVE IS ALONG 43W S OF 14N MOVING W 10-15 KT. A LOW-AMPLITUDE INVERTED-V CURVATURE IS NOTED ON SATELLITE IMAGERY FROM 9N-12N. SCATTERED MODERATE CONVECTION IS IN THIS REGION BETWEEN 39W-45W. A TROPICAL WAVE IS ALONG 59W S OF 14N MOVING W NEAR 15 KT. NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THIS WAVE. DUE TO A LACK OF OBSERVATIONS IN THE VICINITY...THE POSITION OF THE AXIS IS BASED ON CONTINUITY. A WEAK TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 74W FROM WESTERN HAITI TO COLOMBIA MOVING W NEAR 15 KT. THE WAVE IS IN AN AREA OF VERY DRY STABLE AIR ALOFT...THUS CONVECTION IS INHIBITED. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 6N11W 8N20W 8N30W 7N40W AND INTO FRENCH GUIANA NEAR 5N52W. IN ADDITION TO ACTIVITY ASSOCIATED WITH TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS MOVING OFF THE W AFRICA COAST FROM 4N-7N E OF 18W. SIMILAR CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 24W-31W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LOW SITUATED OFF THE LOUISIANA COAST EXTENDS A TROUGH ACROSS THE NW GULF TO THE TEXAS/MEXICO BORDER. AN UPPER RIDGE COVERS THE REMAINDER OF THE GULF. DIFFLUENT SWLY FLOW BETWEEN THESE FEATURES IS ADVECTING A DEEP LAYER OF TROPICAL MOISTURE INTO THE REGION AND IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE MEXICAN COASTLINE FROM VERACRUZ TO THE TEXAS BORDER W OF 95W. HEATING-INDUCED THUNDERSTORMS OVER CUBA AND FLORIDA ARE AFFECTING THE GULF WATERS WITHIN 50 NM OF THEIR RESPECTIVE COASTLINES. A BAND OF SCATTERED SHOWERS AND THUNDERSTORMS IS MOVING AHEAD OF A COLD FRONT OVER THE SERN CONUS AND IS BEGINNING TO ENTER THE FAR NE GULF WATERS BETWEEN NEW ORLEANS AND PANAMA CITY FLORIDA. EXPECT THIS FRONTAL TROUGH TO ENTER THE NE GULF MON BEFORE DISSIPATING TUE. A SFC RIDGE EXTENDS FROM THE CENTRAL ATLC ACROSS FLORIDA AND INTO MEXICO PRODUCING LIGHT SOUTHERLY RETURN FLOW THROUGHOUT THE REGION. CARIBBEAN... AN UPPER-LEVEL RIDGE/TROUGH/RIDGE PATTERN REMAINS IN PLACE OVER THE CARIBBEAN. DIVERGENCE ALONG THE SRN EXTENT OF THE WESTERNMOST RIDGE COUPLED WITH LOW-LEVEL WIND SPEED CONVERGENCE IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE SW CARIBBEAN S OF 12N. THIS DIVERGENCE IS ALSO PROVIDING LIFT TO ENHANCE SCATTERED THUNDERSTORMS GENERATED FROM ONSHORE FLOW ALONG THE COASTS OF NICARAGUA AND BELIZE. STRONG SUBSIDENCE ALONG THE BASE OF THE UPPER TROUGH EXTENDING ACROSS THE WINDWARD PASSAGE IS INHIBITING DEEP CONVECTION IN THE CENTRAL CARIBBEAN BETWEEN 73W-83W. DIVERGENCE ALONG THE LEADING EDGE OF THE TROUGH IS GENERATING NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS OVER THE EASTERN CARIBBEAN N OF 14N AS WELL AS OVER HISPANIOLA...PUERTO RICO...AND THE VIRGIN ISLANDS. A STRONG SURFACE RIDGE OVER THE CENTRAL ATLC CONTINUES TO PROVIDE STRONG EASTERLY TRADES THROUGHOUT THE CARIBBEAN. ATLANTIC... A PRE-FRONTAL TROUGH OVER THE EASTERN CONUS IS PUSHING A BAND OF SHOWERS AND THUNDERSTORMS INTO THE W ATLC W OF 80W N OF 29N. A SECOND AREA OF SCATTERED SHOWERS AND THUNDERSTORMS IS BETWEEN 73W-79W N OF 27W. THIS ACTIVITY IS INDUCED BY INSTABILITY ALONG AN UPPER SHORTWAVE TROUGH. SWLY UPPER FLOW AROUND A HIGH EAST OF THE WINDWARD ISLANDS IS ADVECTING MOISTURE INTO THE ATLC S OF 23N AND W OF 55W. THE REMAINDER OF THE DISCUSSION AREA IS DOMINATED BY A VERY STABLE SURFACE RIDGE ANCHORED BY A 1028 MB HIGH PRESSURE CENTERED NEAR 35N35W SW OF THE AZORES. THIS RIDGE IS MAINTAINING MODERATE EASTERLY FLOW THROUGHOUT THE ERN AND CENTRAL ATLC. $$ WADDINGTON