000 AXNT20 KNHC 282338 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT APR 28 2007 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 4N10W 3N28W 2N40W 2N52W. SCATTERED MODERATE CONVECTION IS WITHIN 60-80 NM N OF THE AXIS BETWEEN 22W AND 34W. A CLUSTER OF MODERATE TO STRONG CONVECTION IS INLAND OVER SW AFRICA NEAR 8N10W. CLUSTERS OF SIMILAR CONVECTION ARE ALONG THE NE COAST OF BRAZIL. ...DISCUSSION... GULF OF MEXICO... A DYING COLD FRONT CONTINUES TO MOVE SOUTH ACROSS SOUTH FLORIDA GENERATING SCATTERED SHOWERS OVER THE MIAMI-DADE COUNTY. A MID/UPPER TROUGH MOVING OVER THE EASTERN US CLIPS THE NE GULF WATERS AND SUPPORTS THIS WEAK FRONTAL BOUNDARY THAT ENTERS THE DISCUSSION AREA NEAR 31N76W. A RIDGE DOMINATES THE REMAINDER OF THE GULF WITH NEARLY ZONAL FLOW. THIS RIDGE CONTINUES TO PUMP TROPICAL MOISTURE OVER THE GULF AND NORTH-CENTRAL FLORIDA BUT IS PRODUCING MAINLY SCATTERED HIGH CLOUDS. A DIFLUENT PATTERN ALOFT IS ENHANCING SOME SHOWER/TSTM ACTIVITY ACROSS THE EASTERN SIERRA MADRE MOUNTAINS IN MEXICO. SURFACE RIDGE CONTINUES TO BUILD ACROSS THE GULF ANCHORED BY A 1022 MB HIGH OVER LOUISIANA AND THE NORTHERN GULF. THIS FEATURE WILL BE IN CONTROL OF THE WEATHER PATTERN ACROSS THE GULF DURING THE NEXT FEW DAYS AS IT MOVES E ACROSS THE SE US. MOSTLY LIGHT WINDS ARE CURRENTLY BLOWING ACROSS THE GULF. CARIBBEAN SEA... SHORTWAVE UPPER TROUGH OVER THE W ATLC DIPS INTO THE N CARIBBEAN THROUGH HISPANIOLA WHERE IS GENERATING SOME SHOWER ACTIVITY. AN UPPER RIDGE STRETCHES E TO W ACROSS NORTHERN SOUTH AMERICA AND CENTRAL AMERICA THEN EXTENDS N OVER THE W CARIBBEAN INTO CUBA AND THE BAHAMAS. THIS RIDGE IS GIVING THE AREA SOUTH OF 16N MOSTLY ZONAL FLOW. IT IS ALSO ADVECTING TROPICAL MOISTURE ACROSS PANAMA AND COSTA RICA. THIS COMBINED WITH THE CLOSE PROXIMITY OF THE EPAC ITCZ IS PRODUCING CLUSTERS OF MODERATE CONVECTION MAINLY NEAR THE COLOMBIA/PANAMA BORDER AND OVER WESTERN PANAMA. TRADE WIND SHOWERS...CHARACTERIZED BY THEIR SHORT DURATION AND LIGHT INTENSITY ARE MOVING ACROSS THE LESSER ANTILLES INTO THE E CARIBBEAN. THESE SHOWERS ARE ALSO AFFECTING PUERTO RICO AND THE US/UK VIRGIN ISLANDS. MODERATE TO STRONG ELY WINDS DOMINATES THE BASIN. ATLANTIC... SHORTWAVE TROUGH IS OVER THE W ATLC BETWEEN 63W-70W. A SFC TROUGH...REFLECTION OF THIS FEATURE IS ANALYZED ON THE 18 Z MAP ALONG 65/66W FROM 24N-29N. A SWIRL OF LOW/MID CLOUDS IS SEEN ON VIS SAT IMAGERY ASSOCIATED WITH THESE FEATURES. UPPER RIDGE COVERING THE CARIBBEAN EXTENDS AN AXIS JUST E OF THE SHORTWAVE OVER PARTS OF THE W-CENTRAL ATLC. WEAK UPPER TROUGH ENTERS THE AREA NEAR 30N40W THEN EXTENDS SW TO 20N50W. THIS IS A RATHER BENIGN FEATURE PRODUCING ONLY WIDELY ISOLATED SHOWERS. THE REMAINDER OF THE ATLC IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A 1029 MB HIGH WELL N OF THE REGION. PATCHES OF LOW LEVEL MOISTURE DRIVEN BY MODERATE TO STRONG TRADE WINDS ARE FOUND UNDER THE INFLUENCE OF THIS RIDGE. $$ GR