000 AXNT20 KNHC 202347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN MAY 20 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 10N14W 5N20W 4N35W 3N45W 2N52W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 2.5N-7N BETWEEN 15W-23W. SIMILAR CONVECTION IS OVER SW AFRICA. SCATTERED MODERATE CONVECTION IS WITHIN 25-50 NM EITHER SIDE OF THE AXIS BETWEEN 25W-29W. ...DISCUSSION... GULF OF MEXICO... WEATHER CONDITIONS ARE PRETTY QUIET ACROSS THE GULF THIS EVENING THANKS TO THE INFLUENCE OF A SURFACE HIGH PRES LOCATED OVER THE SOUTHEAST OF UNITED STATES. MOIST SE WIND FLOW...COMBINED WITH UPPER DIFFLUENCE...IS GENERATING SCATTERED SHOWERS OVER THE NW QUADRANT OF THE REGION. MODERATE TO FRESH NE WINDS PERSIST OVER THE CENTRAL AND EASTERN GULF. ALOFT...A RIDGE DOMINATES THE GULF AND EXTENDS FROM AN UPPER HIGH ANCHORED OVER SOUTH MEXICO. WLY WIND FLOW ON THE NORTHERN PERIPHERY OF THE RIDGE ARE ADVECTING UPPER LEVEL MOISTURE ACROSS MEXICO AND THE WESTERN HALF OF THE GULF. THESE WINDS ARE ALSO ENHANCING SCATTERED SHOWERS/TSTMS OVER CENTRAL MEXICO...INCLUDING MEXICO CITY. HIGH PRES WILL REMAIN IN CONTROL OF THE WEATHER PATTERN ACROSS THE GULF DURING THE NEXT FEW DAYS. WINDS WILL SHIFT MORE E TO SE AND INCREASE SLIGHTLY THROUGH MIDWEEK AS HIGH PRES STRENGTHENS OVER THE W ATLC. CARIBBEAN SEA... A SFC TROUGH EXTENDS FROM THE CAYMAN ISLANDS TO A 1008 MB SFC LOW LOCATED NEAR 11N80W AT 20/1800 UTC. THE WIND SHIFT ASSOCIATED WITH THIS TROUGH IS CLEARLY DEFINED ON SURFACE DATA AS WELL AS ON A QUIKSCAT PASS FROM THIS MORNING...WHICH SHOWED MODERATE ELY TRADES E OF THE TROUGH AXIS AND LIGHT NELY WINDS TO THE W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE ASSOCIATED WITH THE TROUGH/LOW. THIS SHOWER/TSTM ACTIVITY AFFECTS THE CARIBBEAN PLAINS OF NICARAGUA...THE SW CARIBBEAN AND JAMAICA. MODERATE TO STRONG CONVECTION IS ALSO SEEN OVER PANAMA AND COSTA RICA DUE TO THE PRESENCE OF THE EPAC ITCZ AND A DIFLUENT PATTERN ALOFT. ANOTHER SFC TROUGH FROM THE W ATLC IS TRIGGERING SOME SHOWER ACTIVITY OVER EASTERN CUBA AND THE REGIONAL COASTAL WATERS. ALOFT...BROAD UPPER LEVEL RIDGE ANCHORED OVER NORTHERN VENEZUELA COVERS MOST OF THE BASIN. WLY UPPER LEVEL FLOW IS NORTH OF THE RIDGE AXIS THAT EXTENDS WWD ACROSS CENTRAL AMERICA. TRANQUIL WEATHER CONDITIONS ARE FOUND OVER THE EASTERN CARIBBEAN UNDER A DRY/SUBSIDENT ENVIRONMENT. THE TROUGH AND ITS ASSOCIATED LOW PRES WILL REMAIN NEARLY STATIONARY THROUGH MID WEEK. MODERATE TO FRESH ELY WINDS WILL CONTINUE TO BLOW ACROSS THE BASIN DURING THE NEXT SEVERAL DAYS AS HIGH PRES BUILDS NORTH OF THE AREA. ATLANTIC OCEAN... A TROUGH/RIDGE/TROUGH PATTERN COVERS THE ATLC FORECAST AREA. FROM W TO E...AN UPPER TROUGH EXTENDS FROM A VIGOROUS UPPER LOW OVER NEW ENGLAND TO THE NW BAHAMAS/STRAITS OF FLORIDA. THIS FEATURE SUPPORTS A FRONTAL TROUGH WHICH RUNS FROM NEAR 30N66W TO SOUTH FLORIDA NEAR 25.5N80W. THIS TROUGH COMBINED WITH STRONG NELY WINDS PRODUCED VERY LOCALIZED HEAVY RAIN ACROSS THE NORTHEASTERN PORTIONS OF MIAMI DADE COUNTY THIS MORNING. A DISSIPATING TROUGH EXTENDS FROM 30N63W TO THE SE BAHAMAS. BETWEEN TROUGHS...THERE IS AN EXTENSIVE AREA OF CLOUDINESS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS. A RIDGE EXTENDS FROM NORTHERN VENZUELA INTO THE CENTRAL ATLC THROUGH PUERTO RICO AND THE LEEWARD ISLANDS. AN UPPER LOW IS EMBEDDED IN THE RIDGE NEAR 26N45W BUT DOES NOT APPEAR TO PRODUCE ANY SIGNIFICANT WEATHER. A TROUGH EXTENDS FROM THE LOW TO THE DEEP TROPICS NEAR 8N53W. E OF THE TROUGH...THERE IS A RIDGE COVERING FROM THE EQUATOR TO 25N AND EAST OF 40W. A JETSTREAM BRANCH WITH CORE WINDS OF 70 TO 90 KT LIES BETWEEN THESE TWO UPPER FEATURES. WV IMAGERY SHOWS A BROAD BAND OF TRANSVERSE HIGH CLOUDS ASSOCIATED WITH THIS TROPICAL JET THAT RUNS FROM NORTHERN SOUTH AMERICA ALL THE WAY NE AND E TO THE AFRICAN COAST NEAR 21N17W. AT THE SURFACE...A 1036 MB HIGH CENTERED NEAR THE AZORES DOMINATES THE EAST AND CENTRAL ATLC WITH WIDESPREAD FAIR WEATHER AND MODERATE ELY TRADE WINDS ACROSS THE REGION. $$ GR