000 AXNT20 KNHC 182350 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON JUN 18 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. ...TROPICAL WAVES... A LARGE AMPLITUDE TROPICAL WAVE EXTENDS FROM 15N53W TO SURINAME MOVING WEST 15 KT. THIS IS A WELL DEFINED BROAD WAVE APPROACHING THE WINDWARD ISLANDS. SCATTERED MODERATE CONVECTION IS WITHIN 200 NM EITHER SIDE OF THE WAVE AXIS FROM 9N-12N. CLUSTERS OF MODERATE CONVECTION ARE ALONG THE SURINAME/FRENCH GUIANA BORDER. MOISTURE FROM THIS WAVE SHOULD BEGIN TO AFFECT THE WINDWARD ISLANDS EARLY TUE...AND PUERTO RICO AND THE VIRGIN ISLANDS ON WED. A SOUTHWESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 82W/83W SOUTH OF 14N MOVING WEST 10 TO 15 KT. THIS WAVE DOES NOT SHOW UP WELL ON SATELLITE IMAGERY. MOST OF THE CONVECTIVE ACTIVITY IS WITHIN THE ITCZ OVER COSTA RICA AND PANAMA WHERE SATELLITE IMAGERY SHOWS CLUSTERS OF SCATTERED MODERATE CONVECTION. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N15W 6N30W 6N40W 7N50W 8N60W. A LARGE CLUSTER OF MODERATE TO STRONG CONVECTION IS MOVING OUT OF AFRICA COVERING FROM 10N-15N BETWEEN 10W-16W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 5N-11N BETWEEN 21W-28W. ALTHOUGH THIS CONVECTIVE ACTIVITY HAS A GOOD CONTINUITY ON THE HOVMOLLER DIAGRAM...IT HAS DIMINISHED SINCE YESTERDAY. WILL CONTINUE TO MONITOR THIS ACTIVITY THAT MAY BE ASSOCIATED WITH A NEW TROPICAL WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN 30W-42W. ...DISCUSSION... THE GULF OF MEXICO... AS OF 2100 UTC...A 1021 SFC HIGH IS CENTERED OVER THE W ATLANTIC NEAR 29N74W. HIGH PRESSURE RETURN FLOW FROM THIS HIGH DOMINATES THE GULF OF MEXICO. 10-20 KT SLY FLOW COVERS THE ENTIRE AREA. MOIST ONSHORE FLOW IS PRODUCING SCATTERED MODERATE CONVECTION WITH NUMEROUS LIGHTNING STRIKES OVER THE NE CORNER OF THE GULF FROM 27N-31N BETWEEN 84W-91W. THIS SHOWER/TSTM ACTIVITY IS ALSO AFFECTING THE FLORIDA PANHANDLE...SOUTHERN ALABAMA AND SE LOUISIANA. DIFFLUENCE ASSOCIATED WITH AN UPPER RIDGE THAT COVERS THE ENTIRE GULF IS ENHANCING THIS ACTIVITY. THE RIDGE IS ANCHORED ON A HIGH LOCATED OVER THE BAY OF CAMPECHE NEAR 21N94W. THERE ARE SOME SHOWERS OVER THE BAY OF CAMPECHE WHILE CONVECTION CONTINUES TO FLARE UP EVERY AFTERNOON OVER SOUTH-CENTRAL FLORIDA. EXPECT MORE OF THE SAME DURING THE NEXT 24 HOURS. THE CARIBBEAN SEA... A DRY AND STABLE AIRMASS IS DOMINATING THE BASIN...WITH 20 KT TRADEWINDS COVERING A LARGE PORTION OF THE CARIBBEAN S OF 18N BETWEEN THE WINDWARD ISLANDS AND 85W. CLUSTERS OF MODERATE CONVECTION ARE OVER NORTHERN VENEZUELA AS WELL AS OVER COSTA RICA AND PANAMA MAINLY ASSOCIATED WITH THE ITCZ AXIS ALONG 8N/9N. ALOFT...THE UPPER LEVEL HIGH OVER THE BAY OF CAMPECHE IS PRODUCING NLY FLOW OVER THE W CARIBBEAN W OF 80W. ANOTHER UPPER LEVEL HIGH IS CENTERED E OF THE WINDWARD ISLANDS NEAR 15N52W. IN BETWEEN... THERE IS A TROUGH THAT EXTENDS FROM HISPANIOLA TO PANAMA. A TROPICAL WAVE WILL AFFECT THE WINDWARD ISLANDS TUE. SEE ABOVE. THE ATLANTIC OCEAN... ALOFT...A TROUGH/RIDGE/TROUGH PATTERN COVERS THE FORECAST AREA ALOFT. AN UPPER TROUGH IS OVER THE W ATLANTIC N OF 20N BETWEEN 60W-80W. AN UPPER LEVEL HIGH IS OVER THE CENTRAL ATLANTIC NEAR 27N43W. ANOTHER LARGE UPPER LEVEL HIGH IS CENTERED OVER THE TROPICAL ATLANTIC NEAR 15N52W. A TROUGH IS OVER THE E ATLANTIC N OF 20N AND E OF 30W. AT THE SURFACE...A 1021 HIGH IS CENTERED OVER THE W ATLANTIC NEAR 29N74W. A 1016 MB LOW IS FURTHER E OVER THE W ATLANTIC NEAR 28N63W. A SURFACE TROUGH EXTENDS SW FROM THE LOW TO NEAR 25N68W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 150 NM AHEAD OF THE LOW/TROUGH. A 1023 MB HIGH WITH FAIR WEATHER IS OVER THE CENTRAL ATLANTIC NEAR 27N47W. IT WILL REMAIN STATIONARY DURING THE NEXT 24 HOURS WHILE THE LOW IS EXPECTED TO DISSIPATE. THE 18/21 UTC SAHARAN AIR LAYER FROM CIMSS SHOWS AFRICAN DUST COVERING A GOOD PORTION OF THE E-CENTRAL TROPICAL ATLC. THE LEADING EDGE IS REACHING 45W. $$ GR